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The complete Allison 1000/2000/2400 info and swap guide thread

803788 Views 825 Replies 138 Participants Last post by  MaxPF
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 that regulate the pressure on the oncoming 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 off-going clutch. In the event of a 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 controlled by 3 normally closed solenoids, C, D, and E. These solenoids are strictly binary, applying either full line pressure or exhaust to its 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 off-going 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 have 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 4l60Es and 4L80Es. 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 bell housing and gets its signal from the pump vane ribs in the converter housing. On 6-speed GM apps, the bell housing 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 tail housing. 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 4L60Es. There are 2 receptacles on the NSBU. The 4-pin gives the TCM information regarding the gear selected, while the 7-pin accesses switches are used for P-N starter lockout and backup 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 - backup 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 backup 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.
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EVIguy, I am not sure. I see on the 4bt wiring diagram an input for torque limit control switch and analog torque transmission interface. If you look at the allison info it looks like torque management goes thought the J1939 (data) bus (for SEM). None of those are the same language so to speak.

131314


131315
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Yes, I did see that on the wiring info but on the stock wiring between my 5 speed MD Allison and ISB there is just the shielded J1939 which leads me to believe that its done via CAN.
There are no wires in locations 36 and 40 on my ECM.
I believe the torque management is only required on higher power engines so the 4bt may not be wired for it since it is well below the threshold of needing it
Hi Guys,

Been lurking in this thread for a while.
Have read thru all 41 pages multiple times.
I'm brain fried.
Making a wiring harness scares me and can't seem to make sense of what TCM I should buy.
If I'm posting in the wrong thread apologies in advance.

My project is to put an '06 Allison 6 speed in a 1989 Coachman Catalina Motorhome. Currently has a Carb'ed 454 gas motor. i.e. no electronics & a THM400 tranny. Am looking to buy a wiring harness & a Allison MD TCM that will accept an analog TPS input. Or somebody that can re-flash an Allison MD TCM to those specs & tell me what TCM I should buy from a local salvage yard.

I'm a retired Navy Submarine ET living on a fixed income so while I have some money I'm not a rich guy.
I'm electronically competent & digital savy with strong mechanical skills.
I have access to a competent driveline shop who can cut & balance a drive shaft.
The 454 has headers (smog deleted) & will upgrade to EFI (prolly the Holley system).
Would like to have the Allison tap shift so I can lock it out of 5th or 6th cuz' i don't think the 454 will pull a hill in overdrive.
Intention is to use a rocker switch on the dashboard for gear selection when in "M", else operate in "D" w/ shift points suitable to a gas motor limited to ~4500 RPM (when on flat roads).

Any help or a pointer to an affordable dealer/seller would be much appreciated.
Thanks in advance & PM's are solicited & desirable.

BTW, I have a '05 4WD 5 speed Allison & torque converter & a A40 TCM which came out of a '05 GMC Duramax which I bought as a spares for my '05 which I'm willing to sell. Will post pic's if desired.
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I suggest talking/corresponding with Jason at transmissiontuner.com. He knows his stuff and has quite a bit of info on the website as well. Good luck!
I suggest talking/corresponding with Jason at transmissiontuner.com. He knows his stuff and has quite a bit of info on the website as well. Good luck!
Thanks for the post, wasn't sure this thread was still active.

I'm in Jason's build queue & I WILL buy a TCM & harness from him because:
1) He is, hands down, the most knowledgeable, most open w/ information, & most ethical individual/company I've talked to to date. A real class act.
2) His labor rates & pricing are very affordable & prolly too low for the market given the service/quality rendered.
3) I need a stable functional transmission that is as close to "plug 'n' play" as is possible.

My issue(s) is/are:
1) I'm an old fart whose physical capabilities are failing,
2) I live in Northern MN & have concerns about surviving another -50F winter (frost bite 2 years running & almost lost my left foot last winter, diabetes sucks).,
3) I don't have a tall door/ceiling shop to do the work in,
3) At the risk of releasing too much personal info, he's recovering from COVID,
4) He's overworked & backlogged till Sept.,
5) The MH was built & geared in the era of the 55 mph National speed limit so the 454 is screaming @ 60 mph & at 70 is way above it's peak torque curve. @ 80 mph (the unofficial speed limit in the right hand lane on Hwy 29) it sounds like it's gonna' throw pistons out the side.
6) Motor swap in a puller MH will be a B.....
7) Towing on a MH isn't just expensive it's F'ing expensive.

i.e. I have a limited time window to do the swap or be condemned to staying off the National Hwy system.

I may have to temporarily, for this winter run south, swap in a 700R4 w/ lock up & baby it (BIG cooler & watch tranny temps).
Was hoping for an affordable temporary Allison 6 speed solution while Jason catches up on his work backlog.
Like maybe somebody started a Jason conversion & for whatever reason gave up on it & has parts for sale (wiring harness &/or Allison MD TCM). This option would simplify Jason's workload, get me on the road sooner, & free up $$$ for the seller at what he/she paid for it.

BTW, his advice/document on TPS's was immensely helpful. And after a little pricing research, it resulted in an optimal ease of installation solution @ the lowest cost. The TCM6000 - Remote Mount TPS Adapter Kit (A-TCM6000) from Pace Performance @ $100.80 + $13.32 (shipping) = $114.12 delivered to my door. Sweet.

Also looking for a EFI Live Flashscan or Autocal V2 as it seems EFI Live screwed up the V3.

Be safe folks & thanks for the response.
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I didn't know about this information, it's cool that I got to you
Success!!!! I hooked the TPS to the TCM, using a diode to prevent the 8V output of the TPS from being applied to the 5V input of the TCM. Worked like a charm. Here's a little video I made showing what it does:


Like I mentioned, I used a diode to block the 8V from being applied to the inputs on the TCM. The inputs have weak 5V pullups, and putting 8V to them could cause damage. Here's a schematic of the TPS to TCM connection:



I only connected it to the "Managed Input" pin for testing, but I am about 99% positive that it needs to be connected to the "Unmanaged Input" pin as well, otherwise the TCM will throw a code and inhibit TC lockup :rasta:

From what I understand, the Unmanaged Torque is the torque being requested by the driver (basically equal to throttle position), while Managed Torque is the torque actually being delivered by the engine. If no torque reduction is enabled they should track each other. Torque reduction on a computer controlled engine could come from a request from the TCM, or from the traction control system, or from the ECM itself due to certain conditions. When that is the case, the torque requested by the driver may be quite different from what is actually being delivered. Since shift speed is dependent on throttle position (unmanaged torque) and shift firmness, trans pressures, and TCC operation are dependent on actual engine output torque, the trans would need to know both for proper operation.

I mentioned in the video that I wasn't sure why the torque readings went negative. Well, thinking about it, this is the actual torque being delivered by the engine. If you are cruising and let off the throttle, the engine torque is now negative - the transmission is driving the engine, rather than the other way around. With that in mind, the readings make sense. Obviously those are not real values. They are just numbers programmed into the TCM to equate to a certain input pulse width.

In the case of a mechanically controlled engine (or an electronic engine with no torque reduction enabled), unmanaged torque and managed torque should always track each other. By connecting the TPS output to both inputs, were faking it. The TCM shoudln't care - it's going to base it's shift firmness off of the managed torque value and adapt to the rest. All that should matter is that the inputs are consistent, which they will be. The only thing we need to do is disable torque management in the TCM, otherwise it will request torque reduction for shifts, and when that doesn't happen it will throw yet another code. Luckily, EFI Live lets us disable TR :D
Max, great work! I'm a member here but I can not see this video or use the link in post 89 for 06 schematics. Any idea?
Max, great work! I'm a member here but I can not see this video or use the link in post 89 for 06 schematics. Any idea?
The link was broken. Its fixed now (y)
MaxPF,
Post #94 you posted a schematic for the TPS - TCM connection. The pic/link isn’t viewable for me. Just trying to make sure there’s no specific way to wire it to both managed/unmanaged inputs besides the 5v limited diode. Both inputs are run in parallel to the TPS?
MaxPF,
Post #94 you posted a schematic for the TPS - TCM connection. The pic/link isn’t viewable for me. Just trying to make sure there’s no specific way to wire it to both managed/unmanaged inputs besides the 5v limited diode. Both inputs are run in parallel to the TPS?
That's actually post #95. Took me a while rummaging through my HD to find that one. It's fixed now.
That's actually post #95. Took me a while rummaging through my HD to find that one. It's fixed now.
Appreciate it!
Has anyone done a 29 spline Ford NP205 onto directly on the back of a 4wd Allison? I can do the female 29 spline input, no issues.

I already have the VSS figured out.
Does anyone happen to have dimensions/specs for the 29 spline male? I'm looking to machine those splines but can't seem to find any info on them other than OD and # of teeth... info like pressure angle if involute, etc.
The splines are metric. 1.25 module, 30° PA, involute splines.
I didn't see the answer to my question in this thread. I am building a custom spud shaft and need to know if the short 2wd Allison output shaft is 29 spline and will mate up to my 241 29 spline input.


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I didn't see the answer to my question in this thread. I am building a custom spud shaft and need to know if the short 2wd Allison output shaft is 29 spline and will mate up to my 241 29 spline input.
The 2WD shaft is 35 spline, IIRC. It is also retained by an end bolt through the yoke. And it has a tail housing that is particular to 2WD.

You need the 29 spline 4WD output shaft. It has fine threads between the t-case splines and the roller bearing surface. You also need the spanner nut that fits those threads. Finally, you need the 4WD extension housing. Make sure you get the 2006-2010 6 speed housing. The earlier housings will work fine, but theyre not as strong. The 2011-later housings have a completely different t-case mounting face, and would require a custom adapter plate to accept a standard round pattern transfer case. Check end play - specs are in the ATSG manual.

If youre using a GM transfer case, whether driver or passenger drop, with a 29 spline Dodge input shaft it will bolt right up to the Allison. The Dodge has a different bolt pattern and will require re-drilling the face of the Allison extension housing to match. Given a choice, Id rather swap a 29 spline input into a GM case.
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The 2WD shaft is 35 spline, IIRC. It is also retained by an end bolt through the yoke. And it has a tail housing that is particular to 2WD.

You need the 29 spline 4WD output shaft. It has fine threads between the t-case splines and the roller bearing surface. You also need the spanner nut that fits those threads. Finally, you need the 4WD extension housing. Make sure you get the 2006-2010 6 speed housing. The earlier housings will work fine, but theyre not as strong. The 2011-later housings have a completely different t-case mounting face, and would require a custom adapter plate to accept a standard round pattern transfer case. Check end play - specs are in the ATSG manual.

If youre using a GM transfer case, whether driver or passenger drop, with a 29 spline Dodge input shaft it will bolt right up to the Allison. The Dodge has a different bolt pattern and will require re-drilling the face of the Allison extension housing to match. Given a choice, Id rather swap a 29 spline input into a GM case.
Can confirm. I installed a dodge np241 input shaft into a gm np241. Bolted right up and splines onto the stock allison output shaft as it should. Much cheaper option that a np261/3.
Hopefully I can figure this out eventually, but its been a mind boggling experience getting my allison to work with my throttle controller. I programed a PIC to take a 0-5V analog signal and send a PWM output on 2 different pins.
I planned sending it to the unmanaged and managed pins on the TCM (01 8.1), but it just will not shift correctly. I now notice that with key on, I am getting voltage coming FROM the tcm on those pins. One has 5v and the other 12v going from the TCM INTO my controller. I have no clue what is going on now. Do I just have a junk TCM that has had me on a wild goose chase for the last 2 years?
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