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If you have ever wondered about Allison transmission codes and what they mean or how to retrieve them....look no further. Read the explanation below and leave a comment here on this post and I will reply with the code details. This is the first procedure a Mechanic carries out when there is a transmission complaint.

How To Retrieve an Allison Transmission Code

With the key on run... press the 2 arrows on your shift pad. You will get a D1 then 4 digits after that. The 4 digit number is the code you're after. To check for more codes press "mode" and D2 will show up with the second code (4 digits). Press Mode again D3 will come up with the fourth code and so on.

For Example: A Speed Sensor code is 2214 2212 or 2223. There are various checks you can perform. If you have a code let me know and I will post detailed transmission code troubleshooting information to help you out.

Allison transmissions come in different series, the 1000, 2000 and 3000 series depending on the size of your vehicle. The electronics is labeled as WTEC 1, 2, 3 and now 4. These are generations of the electronic systems built through the years. WTEC 3 is very common for older trucks, the tell tale sign of this type of system is the 3 plug-ins at the Transmission ECU.

This is a quick overview of Allison Transmission Codes and will be followed with a video demonstration on how to retrieve codes. Newer WTEC 4 systems require software called Allison Doc using a laptop. The video will be focusing on a WTEC 3 system using the shift pad to get codes. If you're a Mechanic, owner operator or truck enthusiast this procedure is the first step to take if you run into problems.

Check out all my Allison Automatic Transmission posts HERE  Full of Troubleshooting and Repair advice. Many faults can be repaired by running a new coaxial wire from the sensor to the ECU. If there is any interference or resistance issues with a signal to the ECU you will end up with a code.


Here are 3 quick videos I made on how to use the trans shift pad to find codes. I set up a code by disconnecting the output speed sensor at the transmission. This will demonstrate what happens when a fault code occurs and what you can do to find out which code it is and how to clear it.

Video 1 - I'm purposely setting a fault code by unplugging the output speed sensor at the transmission.

Video 2 - Retrieving the transmission fault code using the shift pad.

Video 3 - Hooking the speed sensor back up to simulate the repair being completed and clearing the code using the shift pad.

As you can see Allison transmission codes are easy to read and clear using the shift pad. At the very least you can find out what the fault is and relay that information to your mechanic or use it to troubleshoot the problem yourself. I had a service call once in the middle of the winter, the bus was stuck in 1st gear.

Sound familiar? What had happened was the connector and harness accumulated so much ice around it the weight actually pulled the connector out of the output speed sensor socket. That was weird but made for a happy ending. Another common code is '3500' which is the battery voltage feed to the ECU, battery voltage is hard wired to the ECU so if their is any interruption you're going to get that code number.

Please post your comments and questions below and I will get back to you. thanks!

NOTE: This is for a 2009 4th generation Allison Transmission.

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