Allison Automatic Transmission Retrieving Codes

 The Allison Automatic Electronic Transmission offers a quick method to retrieve trans codes without requiring the Pro-Link reader. This is for older models before Allison required shops to have the DOC software to have any hope finding out what the fault is.

 The video above is all about a preset code which in this case is losing the "output speed sensor" signal to the Trans ECU. I unplugged the sensor connector and once you try to move forward the transmission defaults into 1st gear. Without an output speed signal the ECU does not know where the transmission output speed is at... so it goes into this mode to protect the transmission because of the programming set up by Allison.

 The output speed sensor can be checked out with an ohm meter which averages around 350 ohms depending on ambient temperature. Of course the wiring and connections is a step that should not be ignored. Any kind of resistance in the 30 foot harness running to the driver's cab will give a false signal. Opens and shorts are possible as well since the wiring is exposed to the environment. CHECK OUT THESE PREVIOUS POSTS ON THE ALLISON 3000 SERIES AUTOMATIC TRANSMISSION

Allison Transmission Codes & How To Retrieve Them

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.

UPDATE - VIDEOS  DEMONSTRATING HOW TO RETRIEVE AND CLEAR ALLISON TRANSMISSION CODES USING THE SHIFT PAD.

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!

CLICK HERE FOR THE ALLISON SHIFT SELECTOR OPERATION AND CODE MANUAL.
NOTE: This is for a 2009 4th generation Allison Transmission.

Allison 3060 Automatic Transmission Fault Codes

 Here are fault codes that a reader left on a comment wanting to know what they were. The Allison 3060 Automatic Transmission is all electronic with sensors, solenoids a wiring harness and the Transmission ECU (electronic control unit).

The codes can be retrieved by pushing the 2 arrows at the same time (key on) to retrieve the 4 digit fault codes. Another method is to use the Pro Link Hand Held Reader. To clear the codes after you've repaired the problem hold the mode button until you hear 2 beeps. This has to be done during code retrieving.

Code 2511 means the output speed sensor has a zero speed reading. Check the speed sensor and connection, the ohm reading should around 300 ohms. Also check the ECU connectors. Make sure they are tight,clean and undamaged. Check the fluid level and check wiring to the sensor has no opens, shorts between wires or shorts to ground.

Code 2522 is related to 2511.... 22 being a sub-code.

Code 2312 is the shift selector. Check ECU for connectors, shift selector connector, check selector for proper operation and check the wiring harness for opens, shorts between wires and shorts to ground.

We have had lots of wiring issues and repaired a lot of these problems by running a new coaxial wire from the sensor to the ECU. There seems to be some resistance in the wire that causes improper signals to be relayed to the ECU.

Another area there has been faults is the shift selector pad. You can get a kit for the selector which isn't hard to replace.

If it's hard to push the selector to get into gear that's the first sign of trouble and a new selector pad would fix the problem. Here are all the posts I have produced on the Allison 3060 transmission with troubleshooting and repairs included. Scroll down and you will see some more Mechanic Information on the output sensor circuit.
Got Questions ? Please a comment..

Allison Automatic Transmission Troubleshooting MD 3060 Code 2116

The Allison automatic transmission MD 3060 is all electronic running off direct battery power to a series of relays, fuses and modules. The ECU (electronic control unit) for the transmission reads and controls inputs and outputs. Inputs include engine speed, output speed, turbine speed (the trans internal drive shaft) and throttle position. It computes these inputs into smooth shifts according to these variables.

The TPS Cable Complete - It's Located In The Engine Compartment Area

If it receives a bad signal everything goes to hell in a handbag. Code 21-16 is a trouble code for the Throttle Position Sensor. One of my newsletter subscribers from North Carolina has a 1996 Holiday Rambler motor home with a 5.9 Cummins diesel engine. He's dealing with this code and asked me to help him out.

The TPS control has 3 wires to it, one sends a 0 to 5 Volt signal to the ECU which regulates shifting patterns using these voltage readings. Full throttle and idle can be determined this way, if the wrong reading is sent then you will get a hard shifting scenario.The other 2 wires are the battery voltage and ground.

21-12 Code indicates that the ECU is receiving 14 counts or less. The TPS works with counts and 14 is too low so the problem might be at the closed throttle end of the TPS travel. The first check to make is the cable for frayed wires hanging up somewhere or a bad wire in the 3 wire harness.

My Crude Wiring Diagram Showing The Simplicity Of The TPS Circuit.

I've seen a couple of bad cables and have also replaced all three wires from the TPS to the Trans. ECU. You can check the wires for grounds, shorts or open circuits. If you replace the TPS you can reset it by cycling the ignition 5 times to reset the 0% and 100% throttle position or use the 'ProLink' Reader to reset the system.

Mechanic Troubleshooting - Allison Transmission Wiring

Our fleet has absolutely zero manual transmissions, school bus drive trains are unless requested differently come standard with Allison MD 3000 electronic transmissions. Once they get a few years use there are electrical glitches that occur.

In this case the code pointed to the C3 pressure switch. This switch reads the clutch pack #3 oil pressure in the transmission module. It activates at around 37 psi when pressure is operating the clutch release and engagement.

If it fails, a code 32 will pop up. Most times the wiring is at fault so we will check the continuity from the ECU to the Trans. Module. (shown in the photo above)
At the front end the blue connector has to be disconnected from the ECU where the appropriate terminals have to be probed and checked for resistance. The Allison troubleshooting manual is a "must have" for this procedure. For newer units the WTEC 3 is required(world transmissions electronic controls). These manuals are available at an Allison dealer.

You can tell if the system is in the 3rd generation from the 3 connectors at the ECU. In this case the ECU is located under the driver side floorboard attached to the body(Thomas 1999 Saf-t-liner).

The resistance read 25 ohms which is excessive. As with other codes replacing wiring has become a common occurrence. We use shielded wiring which we run front to back to eliminate the defective wire. Many times if transmissions act up and shift awkwardly in wet weather there's a good chance you have a wiring issue.

How To Manually Check for Transmission Codes

Press the 2 arrows on the shift pad with key on and read the 4 digit code that comes up. Record the first 4 number code then press mode which will bring up a second code(if any) . I hope this mechanic information has helped you out.

Allison Transmission Problems-Hard Shifting

Allison Transmission Problems vary and one typical complaint is hard shifting. I recently looked at a 1999 Thomas Saf-t-liner [pusher] with an Allison MD 3000 series transmission. It had a hard shift into 2nd gear and a hard downshift as well. No codes came up so it was time to check the mechanical side and do a clutch pressure test. The test has to be turned on "enable clutch test" with the "ProLink" so each shifting range can be turned on with the unit running in the shop.

The pressures are compared to main convertor pressure and sits around 270 psi on this test. The individual clutch pressures must be within 5 psi. If there is a big difference that tells us the clutch itself is worn or there is a hydraulic problem. This test revealed no problem in this area and one conclusion could be a clutch that has to be physically inspected for imperfections. There is always 2 clutches applied to get a forward gear in this case it's C1 and C4 for 2nd gear.

The next step is a big one, whether to disassemble the trans and inspect for problems or live with the hard shift. I tried to "fast adapt" the shift parameters with the "ProLink" which did not change anything. This is one of the allison transmission problems you might encounter, if we get into this project any deeper I'll keep you posted.