P0731
DTC P0731
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 Descriptor
DTC P0731
- 1st Gear Ratio Incorrect
Diagnostic Fault Information
Circuit/System Description
The shift control solenoid assembly (SLC1, SLC2, SLC3, SLB1) and the line pressure control solenoid (SLT) are installed on the front valve body. The solenoids linearly control hydraulic pressure in response to signals output from the transmission control module (TCM). SLC1, SLC2, SLC3, SLB1 controls hydraulic pressure to the clutches (C1, C2, C3) and brake (B1) for smooth shifting. According to each shift control solenoid assembly, the transmission shifts from 1st gear into 6th gear and vice versa. As a fail-safe function, if any shift control solenoid assembly abnormality occurs, the TCM will disable the current to the solenoids.
Conditions for Running the DTC
* The ignition voltage is 10.2-15.5 V.
* The engine speed is greater than 400 RPM for 2 s.
* The transmission is not in emergency mode.
* TCM communication is normal.
* Transmission fluid temperature is higher than 20°C (68°F).
* DTCs P0716, P0717, P0721 and P0722 not set.
Conditions for Setting the DTC
* Driving in D range, 1st gear.
* Measured gear ratio deviates more than 20% from expected ratio.
* Determined after 12 times lasting 1 s or more.
Action Taken When the DTC Sets
* DTC P0731 is a Type C DTC
* Torque limitation in drive (D) range 150 Nm (110 lb ft), in reverse (R) range 170 Nm (125 lb ft).
* The TCM freezes transmission adaptive functions.
* The TCM turns OFF all solenoids.
* The TCM allows the vehicle to operate only in second gear and reverse (R) range after a stop.
Conditions for Clearing the DTC
* DTC P0731 is a Type C DTC.
* Measured gear ratio deviates less than 4% from expected ratio.
Diagnostic Aids
Ensure the transmission fluid level, color and odor is correct and there are no leaks. If there are any other transmission DTCs set, diagnose those first.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics AF40-6 (MDK) - Automatic Transmission
Connector End View Reference
Component Connector End Views Sunshade - Left
Description and Operation
Transmission Component and System Description Transmission Component and System 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. Verify the transmission fluid level, color and odor is correct. Refer to Transmission Fluid Drain and Fill Transmission Fluid Drain and Fill.
• If the fluid level, color or odor is not correct
Refer to Fluid Leak Diagnosis Fluid Leak Diagnosis
• If the fluid level, color or odor is correct
2. Operate the vehicle to induce a shift from fifth to sixth gear while observing the following scan tool parameters.
3. Verify the scan tool parameters has to change the proper value referring to the current gear. Compare the values listed below with transmission system description and operation Transmission System Description and Operation Transmission System Description and Operation. Perform this action 2 times.
* Clutch Pressure Control Solenoid Valve 1 Current
* Clutch Pressure Control Solenoid Valve 2 Current
* Clutch Pressure Control Solenoid Valve 3 Current
* Brake Band Pressure Control Solenoid Valve Current
* Shift Solenoid Valve 1
* Shift Solenoid Valve 2
• If the scan tool parameter does not change
Refer to Circuit/System Testing
• If the scan tool parameter change
4. Verify there are no other DTCs are set.
• If any other DTC are set
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.
• If no other DTC are set
5. Operate the vehicle within the Conditions for Running the DTC. It may be helpful to operate the vehicle within the conditions identified from the Freeze Frame/Failure Records data.
6. Verify the DTC P0731 is not set.
• If the DTC is set
Refer to Circuit/System Testing
• If the DTC is not set
7. All OK.
Circuit/System Testing
Note: Circuit/System Verification must be performed before proceeding with Circuit/System Testing.
1. Perform the Line Pressure Check Line Pressure Check to verify proper transmission line pressure.
• If the line pressure not OK
Repair or replace the damaged component as necessary.
• If the line pressure OK
2. Inspect the valve body assembly for a stuck valve, debris, or damage. Refer to Control Solenoid Valve Inspection AF40-6 (MDK) - Automatic Transmission.
• If a stuck open or closed valve is found
Replace the valve body assembly.
• If no stuck open or closed valve is found
3. Verify the DTC does not set while operating the vehicle under the Conditions for Running the DTC.
• If the DTC is set
Replace the K71 Transmission Control Module
• If the DTC is not set
4. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Control valve body replacement, refer to Control Valve Body Replacement Control Valve Body Replacement
* Refer to Control Module References Control Module References for TCM replacement, programming and setup.
* Perform the Transmission Adaptive Functions Transmission Adaptive Functions.