DTC P0736: INCORRECT REVERSE RATIO Chevrolet Silverado 2500

Note. For circuit identification, see CONNECTOR IDENTIFICATION and WIRING DIAGRAMS .

Circuit Description

The Transmission Control Module (TCM) uses input from the turbine speed sensor and output speed sensor to determine gear ratios. The TCM then compares the known gear ratio to the calculated gear ratio for the current gear.

This is a type "A" DTC.

Conditions For Running The DTC

DTC will run under the following conditions

1. The components are powered, and ignition voltage is greater than 9 volts and less than 18 volts.
2. Output speed exceeds 200 RPM.
3. Reverse is selected and attained.
4. DTCs P0716, P0717, P0721, P0722, P0726, and P0727 are not active.

Conditions For Setting The DTC

DTC will set under the following condition

1. DTC sets when the calculated Reverse gear ratio, steady state, detected by the TCM differs from the known Reverse gear ratio.

Action Taken When The DTC Sets

TCM performs the following actions if DTC is set

1. Transmission will lock in Neutral.
2. DTC will be stored in the TCM history.
3. The TCM freezes shift adapts.
4. Illuminates the MIL when active.
5. TCM inhibits TCC engagement.

Conditions For Clearing The DTC

DTC will clear under the following conditions

1. A scan tool can clear the DTC from the TCM history.
2. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without failure.

Test Description

The numbers listed below refer to step numbers in the diagnostic procedure

1. 3 This step tests ignition voltage.
2. 4 This step tests for current Reverse gear ratio.
3. 5 This step tests for noise induced from the engine speed sensor.
4. 6 This step tests for turbine speed not remaining at zero in Reverse.
5. 7 This step checks for evidence of clutch failure.