Coolant temperature sensor (T79), voltage high
Check the cable harness between the coolant temperature sensor and control unit pins 58 and 35. If no fault is found, contact an Allison dealer.
What you'll see
No driver-visible symptom recorded.
System reaction
The Allison fault code number is: P2185.The fault code is set when the control unit has registered a coolant temperature which is less than a calibrated value for more than 10 seconds.The fault code can only be set under the following conditions: The control unit has found a retarder, an analogue engine temperature sensor and a PWM source which requests retarder.The function 'Retarder reduction and retarder gear preselection based on engine coolant temperature' is activated in the calibration.The control unit uses default values for the engine coolant temperature.
Diagnostic depth
The control unit has read a coolant temperature that is less than a calibrated value.
A possible cause of the fault code is an open circuit in one of the electrical cables connected to pin 35 or 58 on the control unit. A short circuit to battery in the electrical cable connected to pin 58 on the control unit can also cause the fault code.