Allison fault code 64-12 retarder modulation request device fault.
1. Check
A. Retarder counts using DDR, to identify problem wires.
B. Wiring harness has no opens, short wires, or shorts to ground.
Retarder modulation sensor failed low
Pulled connections on rocker switch, joystick, ECU and connection and on retarder. Stop light connections good also. Wondering if anyone has any advice or has been down this road. Grounds? not to sure where there are.
Retarder working properly now after being persistent by checking and cleaning all connections, until I was able to clear code 64 - 12. This was the culprit under dash behind kick panel.
What is that? What was the problem? As a fellow owner of a 96 I am curious and needing to commit to memory.
Bosch 12 volt relay for joystick function. Unplugged sprayed with contact cleaner and code cleared.
How did you know it WAS the relay?? Had you seen one before?
Didn't know it was the relay until the code cleared. Followed wires from
Touchpad, Joystick, Rocker switch to all connections, eliminating one at a time until code cleared.