Lmtv Allison transmission code 4512

[ADV DAD]

I have a 1995 lmtv m1078 with wtec 2 transmission ECU. Recently had code 4512 come up which allows starting but puts tranny in DNS (do not shift mode). This 4512 code is the A solenoid. After tracing many wires, checking all relays, fuses, alternator, starter, batteries, etc, the simplest check is check ohms to the A solenoid from the ECU wiring. You can check the Allison trouble shooting guides but the A cable set which is the lower connector, test between wires 2 and 20. If you get 3.5 to 4 ohms, check the temperature chart, then the A solenoid is likely good and chances are the ECU is the problem. After doing everything listed above and fearing the A solenoid was bad requiring more work than i wanted to get involved with, I sent the ECU off to a company in Texas, transmission instruments. They were very helpful via email with the troubleshooting and turns out they were getting the same code when they plugged in my unit to their test station. So it was a bad ECU, $595 and a lot of relief later, they rebuilt the ECU and I am back on the road. I have learned a lot from these forums and thought I should share this experience with the 4512 code with others.

 

[rustystud]

I have a 1995 lmtv m1078 with wtec 2 transmission ECU. Recently had code 4512 come up which allows starting but puts tranny in DNS (do not shift mode). This 4512 code is the A solenoid. After tracing many wires, checking all relays, fuses, alternator, starter, batteries, etc, the simplest check is check ohms to the A solenoid from the ECU wiring. You can check the Allison trouble shooting guides but the A cable set which is the lower connector, test between wires 2 and 20. If you get 3.5 to 4 ohms, check the temperature chart, then the A solenoid is likely good and chances are the ECU is the problem. After doing everything listed above and fearing the A solenoid was bad requiring more work than i wanted to get involved with, I sent the ECU off to a company in Texas, transmission instruments. They were very helpful via email with the troubleshooting and turns out they were getting the same code when they plugged in my unit to their test station. So it was a bad ECU, $595 and a lot of relief later, they rebuilt the ECU and I am back on the road. I have learned a lot from these forums and thought I should share this experience with the 4512 code with others.

Good job going the extra mile to find the cure for your tranny ails. Though the solenoid would have been cheaper to replace if it had been the problem.