Most Common Issues with Allison Transmission

By  //  November 4, 2019

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Allison Transmissions: Products of this brand have been in use for over a century. In terms of their life span, they have established the industry standard that is still relevant.

Products of this brand have been in use for over a century. In terms of their life span, they have established the industry standard that is still relevant.

Although these transmissions are likely to serve you for many years to come, there are still certain issues you may face. 

Today, troubleshooting for these transmissions is much easier with the dedicated Allison DOC software.

Aside from reading all the codes and including built-in troubleshooting, it can even conduct bi-directional functional tests, for example, resetting the adaptive shift.

Despite this convenience, it is still essential to be aware of common sources of malfunction. 

Limp Mode 

This pre-installed mode on Allison 1000 is a special shift table protecting the transmission against catastrophic failure. Bear in mind that thanks to the function, it gets locked into the third gear, while the torque converter is prevented from locking up, and the car part may no longer go into reverse.

Here are a few common triggers for the mode:

  1. High Temperatures

This is the top cause of failure. Excessive heat leads to slipping. If this occurs in hot weather, install a cooler to prevent it. These are generally affordable, easy to find and install. 

  1. Towing

Your transmission may enter the limp mode while you are pulling something heavy (especially with a steep incline). Hardly a convenient time to get hopelessly stuck. 

  1. Engine Tuning

Motorists rarely understand that a driveline tune must be involved in their engine tune. Otherwise, following the procedure, your Allison may start malfunctioning. Taking the tune back to the factory specifications could eliminate the error. 

What This Means

Your Allison part may need a rebuild, or it may be showing a false alarm. In any case, you will be better off clearing the trouble codes.

To do this, scan the code with a code scanner for it to be wiped. It will disappear once the number of the engine on/off cycles without the problem is enough.

Your Allison part may need a rebuild, or it may be showing a false alarm. In any case, you will be better off clearing the trouble codes.

The latest models are controlled via a computer. However, if you possess a tank or a classic car, you could try checking your vacuum lines.

If you notice it bogging and shifting prematurely, this may indicate a connection to the incorrect port. The same conclusion may be drawn if it shifts toward the engine redline. 

GM Trucks

Allison Transmissions on GM Trucks from 2006-07 had to get TCM programming modification, according to an official letter from the car manufacturer. Vehicle owners were advised to bring in their transmissions and get new ones to prevent transmission damage and subsequent failure. 

GM Duramax 

Here, the culprit is often the neutral safety backup switch. You should understand there is a problem if you cannot see the D light up on your gear indicator. It is part number 29540479.  

It is essential to use fluids compatible with Allison, and perform regular maintenance to keep your GM vehicle in shape. This will guarantee you get the most out of your vehicle. Take proper care of it, and your Allison will serve you a long time.