P0731

DTC P0729 or P0731-P0736

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptors
DTC P0729
- Incorrect 6th Gear Ratio

DTC P0731
- Incorrect 1st Gear Ratio

DTC P0732
- Incorrect 2nd Gear Ratio

DTC P0733
- Incorrect 3rd Gear Ratio

DTC P0734
- Incorrect 4th Gear Ratio

DTC P0735
- Incorrect 5th Gear Ratio

DTC P0736
- Incorrect Reverse Gear Ratio

Circuit/System Description

The vehicle speed sensor and automatic transmission turbine speed sensor contains a permanent magnet surrounded by a coil that gives off a continuous magnetic field. As the vehicle is driven, a speed sensor rotor located near the magnetic pickup of the speed sensor coil also rotates. This rotation produces a variable voltage signal that is proportional to the transmission turbine and output speed. The transmission control module (TCM) uses the signals to calculate the gear ratio. The TCM compares the computed ratio to the commanded gear ratio.

Conditions for Running the DTC

* Output speed is 200 RPM or greater.
* The engine speed is 200 RPM or greater.
* Shift to range is completed.
* DTC P0716, P0717, P0721, P0722, P0877, or P0878 is not set.

Conditions for Setting the DTC

P0729

The TCM detects the calculated gear ratio with 6th gear commanded differs from the known 6th gear ratio for 2 seconds or longer.

P0731

The TCM detects the calculated gear ratio with 1st gear commanded differs from the known 1st gear ratio for 2 seconds or longer.

P0732

The TCM detects the calculated gear ratio with 2nd gear commanded differs from the known 2nd gear ratio for 2 seconds or longer.

P0733

The TCM detects the calculated gear ratio with 3rd gear commanded differs from the known 3rd gear ratio for 2 seconds or longer.

P0734

The TCM detects the calculated gear ratio with 4th gear commanded differs from the known 4th gear ratio for 2 seconds or longer.

P0735

The TCM detects the calculated gear ratio with 5th gear commanded differs from the known 5th gear ratio for 2 seconds or longer.

P0736

The TCM detects the calculated reverse gear ratio differs from the known reverse gear ratio for 2 seconds or longer.

Action Taken When the DTC Sets

P0729
* DTC P0729 is a Type A DTC.
* The TCM commands 5th gear.
* The TCM freezes shift adapts.
* The TCM inhibits torque converter clutch (TCC) engagement.

P0731
* DTC P0731 is a Type A DTC.
* The TCM commands 2nd gear.
* The TCM freezes shift adapts.
* The TCM inhibits TCC engagement.

P0732
* DTC P0732 is a Type A DTC.
* The TCM commands 3rd gear.
* The TCM freezes shift adapts.
* The TCM inhibits TCC engagement.

P0733
* DTC P0733 is a Type A DTC.
* The TCM commands 4th gear.
* The TCM freezes shift adapts.
* The TCM inhibits TCC engagement.

P0734
* DTC P0734 is a Type A DTC.
* The TCM commands 5th gear.
* The TCM freezes shift adapts.
* The TCM inhibits TCC engagement.

P0735
* DTC P0735 is a Type A DTC.
* The TCM commands 4th gear.
* The TCM freezes shift adapts.
* The TCM inhibits TCC engagement.

P0736
* DTC P0736 is a Type A DTC.
* The TCM commands neutral.

Conditions for Clearing the DTC

DTCs P0729, P0731, P0732, P0733, P0734, P0735, and P0736 are Type A DTCs.

Diagnostic Aids

* You will have to drive the vehicle in order to experience a condition.
* Incorrect ratio DTCs may indicate a component condition with piston seals, clutch plates, or solenoids.
* Incorrect ratio DTCs may be caused by a faulty turbine or output speed sensor signal.

Reference Information
Schematic Reference

Automatic Transmission Controls Schematics (Allison - Automatic Transmission)
Connector End View Reference

* Component Connector End Views (Connector End Views By Name)
* Inline Harness Connector End Views (Connector End Views By Number)

Description and Operation

* Transmission General Description (Transmission General Description)
* Transmission Component and System Description (Transmission Component and System Description)
* Electronic Component Description (Electronic Component Description)

Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Control Module References) for scan tool information

Circuit/System Verification

1. Perform the Transmission Fluid Level and Condition Check (Transmission Fluid Level and Condition Check) to verify correct fluid level and condition.
2. Perform the Road Test (Allison - Automatic Transmission).
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed on the Freeze Frame/Failure Records data.

Circuit/System Testing

Note: You must perform the Circuit/System Verification first.

1. Perform a line pressure test. Refer to Line Pressure Check (Line Pressure Check).

• If line pressure is low in all ranges, refer to Low Main Line Pressure in All Ranges (Low Main Line Pressure in All Ranges).
• If line pressure is low in a specific range or ranges, refer to Low Main Line Pressure in Specific Ranges, Normal Pressure in Other Ranges (Low Main Line Pressure in Specific Ranges, Normal Pressure in Other Ranges).

Warning

Chock the wheels to prevent the vehicle from moving. Failure to chock the wheels can cause personal injury when the electrical system is repaired.

2. Perform the clutch test. Refer to Clutch Test (Clutch Test).

• If not the specified value, refer to Excessive Slippage and Clutch Chatter (Excessive Slippage and Clutch Chatter).

3. If the above test is normal, refer to Functional Test (Functional Test).

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Speed Sensor Replacement (Allison - Automatic Transmission) , 2WD
* Vehicle Speed Sensor Replacement (Service and Repair) , 4WD
* Control Valve Solenoid Replacement (SS1, SS2, SS3, TCC, and MAIN MOD) (Control Valve Solenoid Replacement (SS1, SS2, SS3, TCC, and MAIN MOD))Control Valve Solenoid Replacement (PCS1 and PCS2) (Control Valve Solenoid Replacement (PCS1 and PCS2)) for PCS1 or PCS2 replacement.
* Control Valve Body Cleaning and Inspection (84. Control Valve Body Cleaning and Inspection)

Repair Verification

If another DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle) and perform the appropriate diagnostic procedure.