Allison 3000 push pad dead - no start - repair tips

[ewo1]

So after trying to help a member out I realized that I have so much info that is not organized I decided to fix the issue.
I will be posting up commented docs that will help you understand how this is built and how it works.

Push pad themselves DO go bad but I have no idea of the frequency rate, but that's another issue.

None of the Allison troubleshooting manuals have any language contained within them on this subject matter so here's my best shot.
This info i am posting comes from the Allison TS2973en troubleshooting manual, 2005. It is for a a Gen3-Gen4 WTEC3 architecture.

Let's begin...
First section - Power to push pad

Before you begin tearing things apart, clean power and ground terminals at the battery, even if they look good!
Check the TCM fuse, 10 amps!

So 12v power originates from the bus battery. It does not go straight to the TCM it first goes to what is called the VIM - Vehicle Interface Module.
I'll explain VIM later.
Once thru the VIM it enters the TCM via the the Gray cable

This is the system feed. These 3 items must be in working order.
It then enters the TCM which in turn gets everything ready for a crank/start.

Your Neutral safety switch circuitry is located within the VIM so one good reason why you need to understand this and realize no power to the vim, no crank!

Power and grounds then exit the VIM via the BLACK cable. this is where you need to make sure power is in fact there.
Power and ground can be found on pin positions 3-Sensor Power, Pin 16 Selector Power and pin 32 ground.
If the display does not light up you got a bad wire/pin or no power coming from VIM.

These diagrams I post will put it all together so do not think this is complicated. It is not!

 

[ewo1]

Allison WTECII & WTECIII ECU’s (TCM’s) Power Failure Troubleshooting Guide:​

The following procedures are technical and should not be attempted if you are unfamiliar with electronics or uncomfortable working with electrical components. Doing this troubleshooting method is at your own risk.

This PDF doc is not my work but, it is really good info, written up by.... Troubleshooting – Transmission Instruments

This is a must have guys!

 

[ewo1]

VIM INFO
What is a VIM and why do I need it?

Explained by Dr. google...

An Allison Vehicle Interface Module (VIM) is a crucial electrical component in Allison automatic transmissions that acts as a gateway between the transmission control module (TCM) and other vehicle systems, including relays, fuses, ignition, sensors, and the shift selector. It ensures proper electrical communication and power distribution, and its VIM-BOX houses relays that are controlled by the TCM for functions like neutral start and other special functions. Issues with the VIM often manifest as power loss, control problems, or shift issues, and troubleshooting involves checking for power, fuses, and continuity in the wiring harnesses.

 

[nikitis]

Even says Neutral Start right there on the PCB.

 

[PorchDog]

ewo1-- I sincerely believe that you are deserving of an Honorary Professorship, or Professor Emeritus title. The help you have provided and the documentation you have dug up or generated or collated into useable form is and will be invaluable help to many people. Thank you for all your efforts!

 

[ewo1]

Porchdog

ewo1-- I sincerely believe that you are deserving of an Honorary Professorship, or Professor Emeritus title. The help you have provided and the documentation you have dug up or generated or collated into useable form is and will be invaluable help to many people. Thank you for all your efforts!

Thank you for the kind words, I really appreciate it very much!

I find this is the best way for me to learn, by reading/studying and ultimately exercising what I learned.
Couple that with a bit of "paying it Forward".

I'm 63 y/o and I have had hundreds of instances where I was down in the gutter and some surprising soul showed up out of nowhere and lent me a helping hand to get me back up on my feet.
It feels real good to be able to give back / help someone else out without expecting anything in return!

 

[ewo1]

GEN 3 - WTEC III
SYSTEM WIRING SCHEMATIC
VIM WIRING

This is the complete wiring diagram , TCM, VIM, sensors, solenoids....
It would be best do download to a flash drive, go to Staples or Office Max, and print it out on the largest paper size available or you'll be using a magnifying glass like me!

This Schematic clearly shows the VIM wiring, the relays within the VIM and what function they perform.

*** According to this schematic, I may stand corrected on a comment I made earlier about Power going to the VIM FIRST. ***

The other drawings in post #1 up above reflect the opposite, that power DOES go thru the VIM first.
This drawing does not reflect that.
What this means is that you need to verify this on YOUR BUS as all busses might not be wired identical.

 

[ewo1]

Allison Transmission 3000/4000 series fault code list
Automatic transmissions Allison 3000 and 4000 Series with electronic control Gen4

 

[ewo1]

Allison Service Tip -1099c

What fluid to use in your tranny ???​

Allison Service Tip 1099C dated 2005 appears to still be the latest manufacturer's recommendations, and covers which fluid is used, and what was installed by the OEM.

1099 Revision X dated 2021 also uploaded.

 

[ewo1]

Diagnosing Transmission via TCM Push Pad
This file is over 5mb, can't upload. Grab it before the link expires.

https://assets.wellertruck.com/reference-materials/troubleshooting-manuals/wteclllshiftselectormanual.pdf

Through readouts on your shift selector, you will be able to monitor transmission oil levels, read diagnostic codes and prognostic information. This brochure will help you understand shift selector readouts and enjoy long, trouble-free operation of your Allison Automatic.

With your shifter you can:

• Check Fluid Levels
• Pull Diagnostic Codes

***Allison preferred method for checking trans fluid level is through the selector and not the dip stick!

 

[ewo1]

Allison - INSTRUCTION SHEET

SUBJECT: Transmission Fluid and Filter Change Procedure
MODELS AFFECTED: 3000 Series TM and 4000 Series TM Transmissions

INSTRUCTION SHEET NO. 355, Rev. B, 2022

Transmission Fluid and Filter Change Procedure (3000 Series prior to S/N 6510069120 and 4000 Series prior to S/N 6610009730)

 

[ewo1]

DATA LINK
Check Trans light came on ??

These are Allison docs that explain what you need to know about the data link.
tip, typically on Allison 2000 's, when "CHECK TRANS' light comes on, it is probably a bad terminating resistor.

 

[ewo1]

Double Cat-Eyes on Shift Selector
4/5th gen
This display indicates a failure of the CAN communication link, the cat-eyes are illuminated in both the Select and Monitor Display, and "CHECK TRANS" light is usually activated.

NOTE: without the CAN link, the Shift Selector cannot display the selected transmission range.
Allison 4/5th Generation Controls shift selectors communicate with the transmission control module (TCM) by exchanging standardized digital messages over the SAE J1939 Controller Area Network (CAN).

​

 

[ewo1]

Allison Transmissions. How To Check & Clear Trouble Codes Without A Scan Tool.​

 

[Rock-N-Ruth]

I nominate ewo1 for the Member of the year Award. It is helpful diligence like this that makes a community strong.

 

[ewo1]

AMTRAN RE VIM
For the curious, this is what a "VIM" looks like in an AMTRAN RE. they are all the same.

Every Allison Transmission requires a Vim in order to properly interface with the chassis/engine.
electronics/sensors.
As you can see, this unit is easy to access, troubleshoot and repair as compared to VIM is a closed, sealed metal box!

 

[ewo1]

"OTHER" non Amtran, BUS VIM

Part number number 29509886 fits an Allison Transmission, Control Module (TCM), also referred to as an Electronic Control Module (ECM), for various models such as the HD4560P, MD3060, and 4500 RDS. It is used in medium and heavy-duty commercial vehicles

Allison Transmission 29556644 VIM (Vehicle Interface Module) superseded part 29509886 - Reaction Force, LLC.

FOR SALE: Used Allison Transmission 29556644 VIM (Vehicle Interface Module) sold by Reaction Force, LLC. Call (503) 862-6322 today!

reactionforcellc.com

Compatible years: 1991-2006 both WTEC 2 and WTEC 3 generations
$549.97

Wiring diagram/pinout for this type of VIM...

https://ccomaq.com.br/suporte/Pins%20TCM%2080%20and%2020%20ways.pdf

 

[ewo1]

This is a WTEC II VIM, contains 2 internal fuses.
Yes, lid screws right off!

For reference, so you can ID what you got on your bus.

 

[ewo1]

This dealer website has pictures and part numbers that will make it easier for you when and if the time comes for repair...
Scroll down to the bottom of the "ALLISON PRODUCTS" page!

ALLISON PRODUCTS – Jultech, Inc.

jultech.com

 

[ewo1]

Allison Transmission (3000 series) fluid and filter change​