Allison 1000 & 2000 Gen 5 Fault Code:P0736 Incorrect Reverse Ratio

CIRCUIT DESCRIPTION:
The TCM uses input from the turbine speed and the output speed sensors to determine gear ratios. The TCM then compares the known gear ratio to the calculated gear ratio for the current range. DTC P0736 sets when the calculated reverse range ratio (steady state) differs from the known reverse range ratio.

ACTION TAKEN WHEN THE DTC SETS:
1. When DTC P0736 is active, the transmission locks in N (Neutral).
2. DTC P0736 is stored in the TCM history.
3. The CHECK TRANS light illuminates (non-OBD II strategy).
4. The TCM forces Variable Modulated Main off.
5. TCM freezes shift adapts (DNA).
6. TCM inhibits TCC engagement.

CONDITIONS FOR CLEARING THE DTC:
Use the diagnostic tool to clear the DTC from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.

DIAGNOSTIC AIDS:
Inspect the speed sensor wiring and connectors for poor electrical connections. Look for the following conditions:
1. A bent terminal
2. A backed-out terminal
3. A damaged terminal
4. Poor terminal tension
5. A chafed wire
6. A broken wire inside the insulation

When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment or the diagnostic tool for a change.

Output or turbine tone wheel damage may cause erratic speed sensor input allowing this DTC to set.

Incorrect ratio DTCs typically indicate mechanical problems with specific clutches, i.e. C3 and C5 for Reverse range.

An incorrect ratio DTC could indicate a hydraulically failed solenoid. Check the DTC information for the specific solenoid.

You may have to drive the vehicle to experience the fault.

Clutch test mode can be used to detect turbine pull-down. If turbine speed is detected, clutch damage may be indicated.