Allison WTECII & WTECIII ECU’s (TCM’s) Power Failure
Troubleshooting Guide
Reference:
https://www.transmissioninstruments.com/troubleshooting/
Page
2
of
4
Brought to you by the Monaco Parts List Project:
http://www.visualsc.com/monaco_parts.php
Instructions for WTECII system (two digits on Your shift selector)
For 1992, 1993, 1994, and early 1995 models if experiencing erratic or no display; especially
when there is cold weather or have retrieved any trouble codes. Have you seen code 69-32
already? Stop troubleshooting = 100% defective ECU!
Locate the ECU (in most RV’s the ECU is mounted directly to the shift pad). If remote shift
selector is used, ECU may be nearby, close to VIM Module or mostly on trucks is mounted
close to the transmission (just follow bundle of wires from transmission).
Disconnect the battery first, then unplug the two oval shape ECU connectors and reconnect
the battery. Check the B connector with black plastic rear side for the numbers (the other side
backing A connector is either white or blue).
Only 8 numbers from 34 are imprinted (both sides of the row). Insert test lamp leads into
corresponding B connector sockets: 9 and 2 then 18 and 11.
Next turn “ON” Ignition switch and insert test leads to 9 and 12. #9; #18 = BATTERY
GROUND; #2; #11 = BATTERY POWER; #12 = IGNITION.
If lamp is bright, the ECU is probably defective unless the display itself is defective. There is
no practical method to check display on the vehicle except to swap selector from another
vehicle. But, if you do have a remote shift selector, you can check the display using ordinary
9V battery and hookup wire.
o
Remove the two 10 amp fuses from the Vehicle Interface Module (2950986) and
connect the 9V battery using bell wire slightly bent on ends; so they can hold inside
connector sockets.
o
Negative 9 volt terminal to B connector #9 and 9 volt positive terminal to B connector
#2 and A connector #8.
o
After a few seconds remote shift selector should start beeping and show on display
“cat eyes “. Just be sure that you have a good connection with wires and sockets.
If display comes “ON”, ECU is defective.
