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.
