Circuit Description
The transmission control module (TCM) uses input from the turbine speed sensor and the output speed sensor (OSS) to determine gear ratios. The TCM then compares the known gear ratio to the calculated gear ratio for the current range.
DTC P0731 is a type A DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0731 Incorrect 1st Gear Ratio
Conditions for Running the DTC
| • | DTCs P0716, P0717, P0721, P0722, P0726, P0727, P0875, and P0876 are not active. |
| • | The components are powered and ignition voltage is greater than 9.0 volts and less than 18 volts. |
| • | Output speed exceeds 200 RPM. |
| • | 1st range is selected and attained. |
Conditions for Setting the DTC
DTC P0731 sets when the calculated 1st range ratio, steady state, differs from the known 1st range ratio.
Action Taken When the DTC Sets
| • | The TCM illuminates the malfunction indicator lamp (MIL). |
| • | The transmission defaults to 2nd or 5th range while diagnostic response is active. |
| • | If the shift selector is moved to NEUTRAL, the transmission will shift to NEUTRAL. |
| • | If the shift selector is moved to REVERSE, the transmission will either lock in NEUTRAL or shift to REVERSE, unless the transmission is compromised by over-speeding or direction change, then the transmission will lock in NEUTRAL. |
| • | DTC P0731 is stored in TCM history. |
| • | The TCM freezes shift adapts. |
| • | The TCM inhibits torque converter clutch (TCC) engagement. |
Conditions for Clearing the DTC
A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without failure.
Diagnostic Aids
| • | Incorrect ratio codes typically indicate mechanical conditions with specific clutches, such as 1-2-3-4 clutch or low and reverse clutch for 1st range. |
| • | Incorrect ratio code could indicate a hydraulically failed solenoid. Observe DTC information for the specific solenoid. |
| • | Clutch test mode can be used to measure stall speed. Observe turbine speed signal. If the turbine speed signal does not return to zero or rises during the stall test, a leak or obstruction in a specific clutch apply circuit could be present. |
| • | You may have to drive the vehicle in order to experience a condition. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests ignition voltage.
-
This step tests speed sensor readings.
-
This step tests for clutch slippage in 1st range shown by turbine speed not remaining at zero.
Step | Action | Value | Yes | No |
|---|---|---|---|---|
Schematic Reference: Automatic Transmission Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 | Measure the transmission fluid level. Refer to Transmission Fluid Check . Is the transmission fluid level correct? | -- | Go to Step 3 | Go to Transmission Fluid Check |
Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data. Is the voltage within the specified range? | 9-18 V | Go to Step 4 | Go to DTC P0562 for low voltage or DTC P0563 for high voltage | |
4 |
Is the correct 1st range ratio shown? | 3.10:1 | Go to Step 5 | Go to Diagnostic Aids |
Is speed sensor data erratic? | -- | Go to the appropriate speed sensor DTC | Go to Step 6 | |
|
Notice: Refer to Transmission Stall Test Notice in the Preface section. Conduct a clutch test for 1st range. Refer to Clutch Test . Did turbine speed remain at zero? | -- | Go to Diagnostic Aids | Go to Step 7 | |
7 |
Is the fluid contaminated or excessive material found in the pan? | -- | Go to Step 8 | Go to Step 9 |
8 | Remove the transmission for overhaul or replacement. Refer to Transmission Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
9 | Inspect for a stuck or sticking pressure control valve. Refer to Control Valve Body Cleaning and Inspection . Did you find and correct a condition? | -- | Go to Step 11 | Go to Step 10 |
10 | Replace pressure control solenoid 3 (PCS3). Refer to Control Valve Solenoid Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
11 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 12 | Go to Step 2 |
12 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
