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Discussion Starter · #781 ·
I'm somewhat confused about mounting a late NP205 transfer case to an Allison. In what situation will a 205 bolt up to an Allison without the need for a spacer? Would installing a 29 spline female input or if the 205 already had a female 205 input be sufficient to mate the transfer case and Allison without using a spacer? Female 29 Spline NP205 Input Gear
If you use that ORD input gear, then you can indeed bolt a round pattern 205 directly to a round pattern 4WD Allison tailhousing. You will have to cut out a semi-circle in the t-case mounting face on the trans for the rear shift rail if you go that route. Make sure you have front driveshaft clearance by doing a mock fit-up. This means removing the front shift shaft, which is it's own PITA, but you don't want to notch out your tailhousing for the shifter shaft only to find that you have to clock the t-case up or push it back, both of which involve spacers anyway.

Max, does this look right?

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You got the basics down fine. As far as EFI Live "version", you will need the latest software for the Flashscan. If you are asking which Flashscan, it's going to be the Flashscan V2.


Thanks for all the fantastic info MaxPF. So if I pick up a late model trans and Tcase from a Dmax can I just run my existing 5 speed TCM to get me going? Using my SAE bell and sensor.
Any years of Dmax?
This keeps my wiring stock and if i want to upgrade to the 6 speed in the future its just TCM/wiring change. Buying a 4X4 housing, output shaft and differant Tcase is almost the same cost as a used Dmax setup.
My console shifter just has PRND, there is no reason to have the 1st position from an operational standpoint?
No. The valve bodies in the 5 and 6 speeds use different solenoids with different electrical characteristics. You cannot use a 5 speed TCM on a 6 speed VB or vice-versa. You CAN swap the 5 speed parts (valve body, shifter shaft, internal wiring harness, and external NSBU/mode switch) into a 6 speed, and that WILL allow you to use the 5 speed TCM. Just make sure you keep all the 6 speed parts nice and clean, put away in ziploc baggies or whatever, as you will have to swap them all back in to run a 6 speed TCM.
 

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Guys, please help! I have been stalking this discussion for two years now. After putting the final touches on my 2002 Ram,5.9 cummings 3500 2wd Allison swap, And removing the bad NV5600, I turned the key and my 13 tooth factory starter drive is hitting the flix plate front with zero engagement, after being on the phone all day with napa we came to the conclusion, that I needed the ten tooth drive. Now for the info, you need to know on my swap. I took the cheap commercial route. My donor trans is out of a low mile 2009 Silverado 2500. my flix plate number is 3918959. what starter do I need? I know I posted this in the wrong way.. and if so give me a hard time but please help, I need this truck running in the worst way!
 

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Discussion Starter · #783 ·
Do you have the part number for the SAE #3 housing? Or, do you know what the original application that housing came out of? Either of those will be needed to definitively determine which starter part # is the correct one.
 
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I'm not sure what the donor vehicle the swap kit came out of. I would think a med duty app of some sort that had the 5.9 Cummins and Allison. I picked it up on eBay for 199.00. no one bid was told it would keep the starter on the same side, so no rewiring needed. here's a photo of the parts I used in the swap. I do have the flexplate ID number 3918959
129075
.
 

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Max, I have a few folks helping me work on this issue. one person told me the starters that were used in the first-gen 5.9 were offset a bit different but were also 13 teeth. here's a photo of the flexplate when I pulled the starter.
129076
 

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Discussion Starter · #787 ·
The listing shows what P/N flywheel housing you have: 3925223. I believe the starter you need is a 6573.
 

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This thread is going strong for over 10 years - THANKS to MaxPF for maintaining it.

Russ
 
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LOTS of good info here. i am starting a new project that includes a lot of this subject matter. i am trying to figure it out for what i need. here is the deal. i have a 1973 chevy suburban that i use for towing a stacker trailer. i dont like the gas 454 engine, not enough torque for me. the trailer weighs close to 10k loaded. i bought a 2003 e350 ford conversion van that was a rollover and removed the entire 7.3l ford engine and harnesses. i bought a sae trans adapter out of a 1995 t444e international that bolts to the ford engine. i had a allison 545 trans on it, but it doesnt have the od i need. the rear end is a rockwell with 5.29 gears, and the engine will rev too much with the diesel. i bought a allison 1000 out of a 2006 chevy silverado with a complete harness and tcm,bcm,ip cluster,steering column, etc so i am trying to hook up the original dash lights for trans lights, and get the tow button and tap shift to work. i am getting wiring diagrams finalised for all of this. i know this is a lot, but am willing to figure it out using the stock components. anybody that might have some input on what will be the hard parts to get working feel free to comment.
 

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5 SPEED TCM (05-EARLIER)

The TCM's for the 5 speeds are very different from the 6 speeds. I don't have any real info on the 6 speed controller, so I will focus on the 5 speed here. AFAIK, the controllers from 00-05 are all nearly identical. Care must be taken if you get your trans from an MD app, as 24 volt controllers do exist. The controller housing is aluminum with rubber isolating mounting feet, and is embossed "CAUTION Do Not Ground to Vehicle Chassis". This generation TCM has two 32-pin receptacles labeled RED (J2) and GRAY (J1), each with different indexing to prevent the wrong plug from being inserted. Looking at each TCM connector, the pins are numbered 1-16 on the top row and 17-32 on the bottom.

J1 Gray Connector

Pin..........Function........................................Allison Color........GM Color................Connection

1.............Vehicle Ground...........................Gray.......................Black/White...........Chassis
2.............Key-On Power..............................Yellow....................Pink.........................Fused Key-On Power
3.............Continuous Power......................Pink........................Orange...................Fused Battery Power
4.............Key-On Power..............................Yellow....................Pink..........................Fused Key-On Power
5.............Vehicle Ground..........................Gray........................Black/White...........Chassis
6.............Input 1.........................................Blue.......................Yellow......................PTO Status (GM Specific)
7.............Input 2.........................................Orange..................Purple......................Service Brake Switch (GM Specific - Notifies TCM that the service brakes are applied so the TCM can de-apply the TCC)
8.............Input 3.........................................Green....................N/A............................PTO Auto Neutral (Not Used On GM Light Trucks)
9.............Input 4.........................................White.....................White........................Unmanaged Torque (GM Specific - connects to ECM/PCM)
10...........Input 5.........................................Yellow....................Gray/Black...............Secondary Shift Schedule (GM Specific - Alerts TCM that 4Lo is engaged so corrections can be made for the t-cases gear reduction on the OSS signal)
11...........Input 6.........................................Green....................N/A............................Range Inhibit (MD Only)
12...........Input 7.........................................Blue.......................N/A............................Retarder Enable (MD Only) (On Gm Vehicles, this is used as the switch input for the Overdrive Lockout Mod)
13...........Input 8.........................................Pink........................N/A............................ABS (MD Only)
14...........Input 9.........................................Orange..................N/A............................N/A
15...........Retarder......................................Yellow....................N/A............................Retarder Request (MD Only)
16...........PWM Throttle..............................White....................Tan/Black.................Managed Torque Signal (GM Specific - Connects to PCM - L18 8.1L Gas Engine Application Only)
17...........Retarder Sensor Power.............Pink.......................N/A.............................VSA (MD Only)
18...........Analog Ground..........................Green....................N/A.............................N/A
19...........Output 1......................................Tan........................N/A.............................N/A
20...........Output 2......................................Orange.................N/A.............................N/A (On Gm vehicles with the ODLO mod, this is the ODLO enabled lamp output)
21...........Output 3......................................White....................N/A.............................Range Indicator (MD ONLY)
22...........Output 4......................................Blue......................Orange/Black............Managed Torque Request (GM Specific - Connects to PCM - L18 8.1L Gas Engine Application Only)
23...........Output 5......................................Pink.......................N/A..............................Range Inhibit Indicator (MD Only)
24...........Output 6......................................White....................N/A..............................N/A
25..........."Check Trans" Output................Green...................Dk Blue.......................MIL Request (On GM Vehicles this is connected to the ECM/PCM)
26...........Vehicle Speed Output...............Tan........................N/A..............................N/A
27...........Vehicle Speed Output...............Pink.......................Yellow..........................Replicated TOSS (Connects to ECM/PCM On GM Vehicles)
28...........Digital Ground............................Yellow...................N/A..............................N/A (May be used as a ground for J1850/ISO9141 link) (On Gm vehicles with the ODLO mod, one side of the ODLO momentary switch is wired to this terminal)
29...........J1939 (CAN) High.......................Red.......................Yellow..........................J1939 Connector (Connects to common CANHI wire on Gm vehicles)
30...........J1850/ISO9141 Data Link.........Blue......................Yellow..........................J1939 Connector (Connects to common J1850 bus on Gm vehicles)
31...........J1939 (CAN) Shield....................Green...................N/A..............................J1939 Connector (not connected on GM vehicles)
32...........J1939 (CAN) Low........................Black....................Dk Green....................J1939 Connector (Connects to common CANLO wire on Gm vehicles)

NOTE: The CAN hi and low wires MUST be run as a twisted pair, and covered with a braided or foil shield. Shield must be grounded or terminated to a CAN shield terminal at one end.

J2 Red Connector

Pin..........Function........................................Allison Color........GM Color................Connection

1.............PSA Input......................................Blue......................Pink.........................Transmission Connector Pin D
2.............PSA Input......................................Pink.......................Dk Blue..................Transmission Connector Pin F
3.............PSA Input......................................White....................Red..........................Transmission Connector Pin E
4.............PSA Input......................................Green...................Lt Green/Black......Transmission Connector Pin K
5.............Shift Selector Input.....................Blue......................Black/White............NSBU Switch - 4 pin connector - Pin A
6.............Shift Selector Input.....................Yellow...................Yellow......................NSBU Switch - 4 pin connector - Pin D
7.............Shift Selector Input.....................Gray......................Gray.........................NSBU Switch - 4 pin connector - Pin B
8.............Shift Selector Input.....................White....................White......................NSBU Switch - 4 pin connector - Pin C
9.............TPS Input......................................Blue......................N/A..........................Throttle Position Sensor pin B (wiper pin)
10...........Transmission Temp Input...........Tan.......................Yellow/Black...........Transmission Connector Pin G
11...........Retarder Temp Input..................Orange................N/A...........................Retarder Temp Sensor (MD apps only)
12...........Engine Coolant Temp Input......Blue......................N/A...........................ECT Sensor (Some MD apps - Not used on GM light trucks)
13...........TSS Input, High...........................Orange.................Orange....................Turbine Speed Sensor pin A
14...........TSS Input, Low.............................Blue......................Lt Blue.....................Turbine Speed Sensor pin B
15...........OSS Input, High...........................Yellow...................Purple/White...........Output Speed Sensor pin A
16...........OSS Input, Low.............................Green..................Lt Green/Black.......Output Speed Sensor pin B
17...........ESS Input, High............................Tan.......................Red/Black...............Engine Speed Sensor pin A
18...........ESS Input, Low.............................Orange................Bk Blue/White........Engine Speed Sensor pin B
19...........TPS Ref. Voltage...........................Pink......................N/A..........................Throttle Position Sensor pin C (max throttle position)
20...........Analog Ground............................Green...................Black......................Transmission Connector Pin H, NSBU Switch 7 pin connector pin D, Throttle Position Sensor pin A (idle position), ECT Sensor, Retarder Temp Sensor
21...........Trans ID.........................................Yellow...................Purple....................Transmission Connector Pin T
22...........Solenoid A, High..........................Yellow...................Lt Blue/White........Transmission Connector Pin L
23...........Solenoid A, Low...........................White...................Red/Black..............Transmission Connector Pin M
24...........Solenoid B, High..........................Pink......................Pink/Black..............Transmission Connector Pin N
25...........Solenoid B, Low...........................Orange................Brown/White..........Transmission Connector Pin P
26...........Solenoid C Output.......................Green..................Lt Green.................Transmission Connector Pin A
27...........Solenoid D Output.......................Blue.....................Yellow/Black...........Transmission Connector Pin B
28...........Solenoid E Output.......................Gray.....................Orange/White.........Transmission Connector Pin W
29...........Solenoid F, Low............................White..................Brown......................Transmission Connector Pin J
30...........Solenoid G, Low...........................Orange................Dk Blue....................Transmission Connector Pin R (04-up only)
31...........Solenoid C, D, E V+ Supply........Tan.......................Brown......................Transmission Connector Pin C
32...........Solenoid F, High..........................Green..................Dk Green/White......Transmission Connector Pin S
Hey man I’ve got a 2004 lb7 and Allison 1000 5spd in a 1997 Chevy 3500 and we’ve got the motor to run and have those 5 wires hooked up like they should and can’t get it to shift it instantly goes into limp every time you put it in gear. Just need a little advice on what to do next?


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Discussion Starter · #792 ·
Hey man I’ve got a 2004 lb7 and Allison 1000 5spd in a 1997 Chevy 3500 and we’ve got the motor to run and have those 5 wires hooked up like they should and can’t get it to shift it instantly goes into limp every time you put it in gear. Just need a little advice on what to do next?


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You need to get the diagnostic codes from the TCM. There are many things that can cause an immediate limp mode.
 

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1964 Chevy C10, Cummins ISB170, Allison 1000 5 speed, full float 9”, ECU Tune, 5/7” static drop
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Does anyone know why a Allison would start make a grinding noise. Then when I apply throttle while driving the trans makes a horrendous squeal around 2000 rpms and will not accelerate as it once has. I think my transmission is smoked.
 

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Discussion Starter · #794 ·
Does anyone know why a Allison would start make a grinding noise. Then when I apply throttle while driving the trans makes a horrendous squeal around 2000 rpms and will not accelerate as it once has. I think my transmission is smoked.
It could be the torque converter, not the trans. Any codes?
 

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1964 Chevy C10, Cummins ISB170, Allison 1000 5 speed, full float 9”, ECU Tune, 5/7” static drop
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It could be the torque converter, not the trans. Any codes?
No codes, but I realized my speedometer is not working. I checked the wiring to the output sensor and all checks out. I’ll pull the sensor this weekend and check it. I hope it’s not the planetary.
 

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Haven’t found a great way to install the TPS for my 4bt/Allison swap, so I started researching the potentiometer option. Anyone running this setup on the Allison 1000 or know if I will run into issues?
I have the factory computer with destroked “controller” box. Thanks!
 

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Hey guys, so been reading this for a few days now. I hope I can be pointed out in the right direction.

I have a 97gmc t6500. It has a 2001 cat engine and had a eaton 6 speed.

I have installed a allison 2500 rds and from what I understand it is a 5 speed. Date is 05E24.

So I have the cooler driveshaft and everything set up.

I am at the wiring harness. Which I did receive a harness and tcm with it. Can anyone give me what wire I need to connect on what pin on the ecu side from the tcm?

Will I have to put risisters for data link? I do not think I have j1939 connection. But you can correct me if I am wrong.

If it is possible to be told what wires I need from ecu to pcm with the pins. I dont want to mess that up and I am on a time crunch.

And if I do need resisters.. where can I get those?

Thank you so much and my apologies if this is alot to ask.

Great thread tho. I know it was mostly aimed at 6 speed conversion but title does mention most allison trans. Thank you again.
I can attach pictures of the harness if need be.
 

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1964 Chevy C10, Cummins ISB170, Allison 1000 5 speed, full float 9”, ECU Tune, 5/7” static drop
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It could be the torque converter, not the trans. Any codes?
I am foolish. The lack of power and squealing noise was a blown boost boot. The output sensor was failed and happened to be coincidence at the same time. Lead the rabbit down the wrong hole. All is good and up working again.
 

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I decided to start a thread devoted to this trans for a couple reasons. First off, there is a LOT, and I mean a LOT of misinformation out there. Second, there is little useful info for some basic specifications on these transmissions. Finally, a lot of guys think they are too complicated or too expensive, when in fact they are no more complicated or expensive than, say, a 4L80E or 48RE that is built to do the same thing. Since I have decided to swap a 1000 into my truck I have been heavily researching all the details. While I still don't have all the answers I want, I do have most that I need, and I figured why not consolidate this information somewhere to help out other folks who contemplate this swap. I think a lot of folks get turned off of an Ally swap simply because the information is sporadic and often contradictory.

With that said, my goal for this thread is to include as much FACTUAL INFORMATION as possible. If info is prefaced by "I think", "Supposedly", "I heard", "My friend said", etc. I don't consider it factual. I don't want a thread full of anecdotal information, but rather facts that people can use to make an informed decision and help them successfully complete a swap. ;) With that said, including unconfirmed info and opinions is fine as long as it is presented as such.

Also, when adding any information, make sure to specify what generation of Allison it belongs to. There is the pre-2004 5 speed, 04-05 5 speed, and 06-up 6 speed, with various revisions among the years. Try to be as specific as possible.

Anyway, with that said I will start with some basic info about the 1000/2000/2400 series.

GENERAL INFORMATION

The Allison 1000/2000/2400 series are torque converter driven, fully automatic transmissions with 5 or 6 forward speeds. 5th and 6th are overdrive gears, and the overall ratios are dependent on model. All have a neutral and reverse gear as well, and the 1000 and 2400 series have a park position which actuates an integral park pawl. The basic max ratings for this series of transmission is 300HP, 550lb-ft input torque without SEM/torque management, 620lb-ft input torque with SEM/torque management, and 850lb-ft turbine torque. These are the ratings published by Allison for MD on-road use. As we know, the ratings for GM pickups with the DMax are higher, but the GVW and duty cycle of a pickup are less than a Md truck, so Allison rates the trans conservatively. No doubt the software in the TCM has a huge impact on the amount of power the trans can really take. GVW and GCW ratings of the trans depends mainly on whether the unit has a park pawl (units with park pawl are rated lower). GVW varies from 19,500lbs for the 1000 series to 33,000lbs for units without park. GCW ranges from 26,000lbs to 33,000lbs. Complete ratings and specs can be found here.

The gear ratios for the various models are as follows:

..........1000..........2000/2400

1st.....3.10...........3.51
2nd....1.81...........1.90
3rd.....1.41...........1.44
4th.....1.00...........1.00
5th.....0.71...........0.74
6th.....0.61...........0.64 (06-up models only)
Rev.....4.49...........5.09

INTERNAL OPERATION

Internally, the transmissions have three planetary gear sets controlled by 5 sets of clutches, labeled C1-C5. 2 clutch packs (C1-C2) are rotating, and transfer input torque to certain elements in the planetary sets, while the remaining 3 sets (c3-C5) are stationary and lock each of the ring gears and their coupled components to the case when engaged. These transmissions contain no bands, sprags, or roller clutches - all gear changes are accomplished by direct clutch-to-clutch changes. Clutch engagements for each gear are as follows:

.............C1........C2........C3........C4........C5

Park..........................................................*
Rev.........................................................
Neu..........................................................*
1st..........................................................
2nd........................................................
3rd.........................................................
4th.........................................................
5th.........................................................
6th......................................................... (06-up models only)

VALVE BODY AND TRANSMISSION ELECTRICAL

Shifting is controlled electronically. The valve body contains 6 (03-earlier) or 7 (04-up) solenoids which control all functions. Solenoids A and B are "trim" solenoids which regulate the pressure to the on coming and off going clutches. both are pressure proportional to current (PPC) solenoids which operate at a frequency of 1KHz. Solenoid A is normally closed, providing full line pressure at zero current and zero pressure at 100% current. Solenoid B is normally open, and provides zero pressure at zero current and full line pressure at 100% current. Solenoid A controls the oncoming and applied clutches while B controls the offgoing clutch. In the event of power or TCM failure solenoid A will default to full pressure while B defaults to zero pressure, giving a limp-home capability. 04-up valve bodies incorporate a G solenoid which reduces the main line pressure by approximately 100psi during idle and low load operation, reducing heat generation. The F solenoid controls TCC apply and release. On 05-earlier models this is a PWM solenoid operating at 100Hz, while 06-up use a PPC solenoid operating at 1KHz.

Shifting is contrilled by 3 normally closed solenoids, C,D, and E. These solenoids are strictly binary, applying either full line pressure or exhaust to it's associated spool valve. The logical combination of these 3 valves determines which clutches are applied. Contrary to what some believe, the solenoids do not directly operate the clutches. The spools and solenoids are arranged so that each shift change will exhaust the offgoing clutch via the solenoid B path while applying pressure to the oncoming clutch via the solenoid A pressure. Because of this, shifts must be sequential - the transmission will not skip gears when upshifting or downshifting. It also means that it is not possible to apply random sets of clutches, although it is possible that the unused solenoid combinations could create a non-valid clutch condition (i.e. C2 and C5 applied) which would create a lockup. There has been anecdotes of aftermarket controllers applying all 5 clutch packs while at speed, but I don't believe it is possible to apply more than 2 clutches with the arrangement of valving in the VB. That is not confirmed however...

Here are the solenoid combos for the various gears:

.............C...........D...........E
Park.............................*
Rev................................
Neu..............................*
1st.....................*.............
2nd.................................. (If power is lost or TCM is inoperative, this is the limp mode gear)
3rd.......*..........................
4th.................................
5th...................................*
6th ???????????????????? (Don't have info for this....)

The VB also contains a pressure switch assembly which gives feedback to the TCM on which solenoids are engaged. The PSA also houses the trans temp sensor, which is a negative temperature coefficient thermistor. All VB electricals are passed through the case using a standard GM 20 pin connector, identical to the one used on the late 4l60E's and 4L80E's. Looking at the connector in the trans, starting with the upper left and working left to right, top to bottom, the pins are labeled A-W, with the letters I, O, and Q not used. The pin assignments and color codes of the INTERNAL wiring harness for 5 speed models are as follows:

A - Dk Green - Shift Solenoid C
B - Orange/Black - Shift Solenoid D
C - Pink - Power to shift solenoids C, D, and E
D - Lt Green - PSA terminal A
E - Red - PSA terminal C
F - Blue - PSa terminal B
G - Orange - PSA terminal E
H - Black - PSA terminal F
J - Brown - TCC solenoid F
K - Tan - PSA terminal D
L - Red/Black - Trim Solenoid A
M - Lt Blue - Trim Solenoid A
N - Gray - Trim Solenoid B
P - Purple - Trim Solenoid B
R - ????? - Line Pressure Solenoid G (04-up only)
S - Black - TCC Solenoid F
T - Tan - PSA terminal F
U - Green - IC to terminal V
V - Green - IC to terminal U
W - Black/Tan - Shift Solenoid E

For 6 speed models, the internal connections are as follows (no color codes - sorry:

A - Shift solenoid C
B - Shift solenoid D
C - Shift solenoid E
D - PSA terminal A
E - PSA terminal C
F - PSA terminal B
G - PSA terminal E
H - PSA terminal F, IMS terminal F
J - TCC solenoid F
K - PSA terminal D
L - Trim solenoid A, TCC solenoid F, main pressure solenoid G
M - Trim solenoid A
N - Trim solenoid B, shift solenoids C, D, and E
P - Trim solenoid B
R - IMS terminal A
S - Main pressure solenoid G
T - IMS terminal E
U - IMS terminal D
V - IMS terminal C
W - IMS terminal B

Other electrical components include 3 (05-earlier GM apps) or 2 (06-up GM apps) variable reluctance speed sensors and an NSBU (Neutral Start back-Up) switch (05-earlier) or IMS (Internal Mode Switch - 06-up). The first speed sensor is in the bellhousing, and gets it's signal from the pump vane ribs in the converter housing. On 6 speed GM apps, the bellhousing speed sensor is deleted, and the TCM instead gets engine speed information from the ECM via the GMLAN bus. The second sensor is the turbine speed sensor in the main housing, and pics up off of either the PTO gear or a stamped steel tone ring that replaces the PTO gear in units without a PTO option. Finally, 2WD transmissions have an output speed sensor in the output housing that reads off of a 40 tooth tone ring on the output shaft. 4WD models use the speed sensor and 40 tooth tone ring in the transfer case tailhousing. 4WD models have a switch input to notify the TCM that 4Lo mode is engaged, and the TCM makes appropriate compensation for the TC low gear ratio.

The NSBU switch on the 01-02 5 speeds is essentially identical to that used on the 4L60E's. There are 2 receptacles on the NSBU. The 4 pin gives the TCM information regarding the gear selected, while the 7 pin accesses switches used for P-N starter lockout and back-up lights. The 4 pin receptacle's pins are marked A, B, C, and D. Depending on the shift position selected, a combination of 2 of these pins will be grounded. Here's the table, with the grounded pins marked with an asterisk:

.............A...........B...........C.........D
P.................................................
R................................................
N...............................................
D................................................
3...................................................
2................................................
1...............................................

Since only 2 terminals or no terminals (in the case of 3rd) are valid combinations, the TCM can sometimes determine if there is a wiring or switch malfunction. The standard wiring color codes and their connection to the TCM J2 connector for the 4 pin receptacle are as follows:

A - Blue - pin 5
B - Gray - pin 7
C - White - pin 8
D - Yellow - pin 6

NOTE: On GM pickups, these wires go to the ECM, which then buffers and feeds them to the TCM. On stand-alone apps, they will be wired directly to the TCM. This is a helpful bit of info for those modding a GM pickup harness ;)

The 7 pin connector on the NSBU has pins labeled A-G, and their corresponding wire colors and assignments are as follows:

A - Not used
B - Tan - Park Accessory
C - Blue - Rev/Park Accessory fuse
D - Green - TCM analog ground (TCM J2 connector, pin 20)
E - Yellow - Park/neutral start battery feed
F - Pink - back-up lamps
G - Orange - Starter relay

03-05 models used a very similar NSBU switch assembly, except they have a single connector that contains all the pins, rather than 2 separate connectors.

06-up 6 speed transmissions no longer use an external NSBU switch. The external switches were prone to failure caused by internal corrosion due to exposure to water. The park and reverse accessory and back up lamp switch functions were moved to the column. Park/neutral and gear selector position info on these transmissions is done with an internal mode switch (IMS) mounted on the rooster comb inside the transmission. Its functions are brought out through the 20 pin connector on the transmission (see above). The F pin on the IMS is common, and depending on position one or more of the remaining pins will be switched to the F pin. Pin A is connected to the ECM, and is used to notify it that the transmission is in either park or neutral, thus allowing the engine to be cranked. The final 4 (B-E) are connected directly to the TCM and tell it what range is selected, NOTE; On GM trucks, the PRNDL is labeled P-R-N-D-M-1, with only those 6 positions available via the column shifter. However, the transmission itself has 7 positions internally - the last position is simply not used in GM vehicles, and the travel is limited in the column shifter so a GM vehicle cannot physically shift into the last position. However, a DIY shifter setup WILL be able to shift into that last position unless it is likewise limited (i.e. using a 3 speed floor shifter rather than a 4 speed floor shifter).

Note that these pin assignments are those of the switch itself, NOT the 20 pin external connector. Refer to the external pinout description above for the 6 speed to find the external pins connected to these internal pins.

............A............B............C............D............E
P....................................*.............................
R..................................................................
N.................................................*...............
D..................................................................
3...............................................................
2..................................................................
1..................................................................

Information continued in later posts.
Hey I know this about your Blazer! Did you modify the core support to fit the inner cooler? Thanks for your time! Dave
 

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This is a little off topic and backwards but here goes.
I'm installing a Cummins ISB170 in front of a ZF8HP trans. I was hoping to use some sort of torque management but cant find any info on what sort of signals the ISB wants to see from the trans so I'm wondering what the Allison sends to the ISB?
 
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