Okay, 731 is a gear ratio error for first gear. This is most likely an internal failure in the transmission. You will need to do pressure tests on the system to see if there is sufficient pressure to engage first gear.
I found the adaptation procedure for when you replace the transmission but the code is what has me concerned.
No, the tachometer signal comes from the ECM.
Roy
P0731-GEAR RATIO ERROR IN 1ST
For a complete wiring diagram, refer to: Electrical Diagrams
When Monitored
The Transmission gear ratio is monitored continuously while the transmission is in gear.
Set Condition
If the ratio of the Input RPM to the Output RPM does not match the current gear ratio when compared to the known gear ratio.
Possible Cause
RELATED TRANSMISSION DTCS PRESENT
INTERMITTENT GEAR RATIO ERRORS
INTERNAL TRANSMISSION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Theory of Operation
The transmission system uses two speed sensors, one to measure input RPM and one to measure output RPM. These inputs are essential for proper transmission operation. Therefore, the integrity of this data is verified through data checks. When in gear, if the gear ratio does not compare to a known gear ratio, the corresponding gear ratio error trouble code is set. The transmission will go into Limp-in mode after four gear ratio error events occur in a given driving cycle.
Diagnostic Test
1. DETERMINING IF RELATED TRANSMISSION DTCS ARE PRESENT
With the scan tool, read Transmission DTCs.
If any of these DTCs are present, perform their respective tests first.
Are there any Loss of Prime, Line Pressure Sensor and/or Speed Sensor DTCs present?
Yes >> Refer to appropriate diagnostic procedure in the Transmission category. If any of these DTC's are present, they will cause a gear ratio error. Perform the test for Loss of Prime first if it is present.
Perform 42RLE TRANSMISSION VERIFICATION TEST - Ver 1. See: A L L Diagnostic Trouble Codes ( DTC ) > Verification Tests.
No >> Go To 2
2. CHECK TO SEE IF P0731 IS CURRENT
With the scan tool, perform the 1st gear clutch test. Follow the instructions on the scan tool.
Increase the throttle angle or TPS Degree to 30° for no more than a few seconds.
CAUTION: Do not overheat the transmission.
Did the Clutch Test pass, Input Speed remain at zero?
Yes >> Go To 3
No >> Go To 4
3. CHECK FOR INTERMITTENT OPERATION
The conditions to set this DTC are not current at this time.
Check the gearshift linkage adjustment.
Gear ratio DTCs can be set by problems in the Input and Output Speed Sensor circuits. If the vehicle passes the Clutch Test and still sets Gear Ratio DTC, check the Speed Sensors for proper operation.
Remove the Starter Relay.
CAUTION: removal of the Starter Relay is to prevent a Transmission NO RESPONSE condition and to disable the starter.
Check the wiring and connectors for the Speed Sensors for a good connection, then perform a wiggle test using the Transmission Simulator, Miller tool #8333 and the Electronic Transmission Adapter kit 8333-1A.
This DTC can also be set under extreme temperature conditions. This is usually caused by an internal problem.
Verify if the problem is only experienced under extreme hot or cold conditions.
With the scan tool, check the EATX DTC EVENT DATA to help identify the conditions in which the DTC was set.
Were there any problems found?
Yes >> Repair as necessary.
Perform 42RLE TRANSMISSION VERIFICATION TEST - Ver 1. See: A L L Diagnostic Trouble Codes ( DTC ) > Verification Tests.
No >> Test Complete.
4. INTERNAL TRANSMISSION
If there are no possible causes remaining, view repair.
Repair
Repair internal Transmission per the Service Information. Check all of the components related to the UD and LR clutches. Inspect the Oil Pump and repair or replace per the Service Information.
Perform 42RLE TRANSMISSION VERIFICATION TEST - Ver 1. See: A L L Diagnostic Trouble Codes ( DTC ) > Verification Tests.
Adaptation procedure when the transmission is replaced.
The adaptation procedure requires the use of the appropriate scan tool. This program allows the electronic transmission system to re-calibrate itself. This will provide the proper baseline transmission operation. The adaptation procedure should be performed if any of the following procedures are performed:
Transmission Assembly Replacement
Transmission Control Module Replacement
Clutch Plate and/or Seal Replacement
Electrohydraulic Unit Replacement or Recondition
1. With the scan tool, reset the Transmission adaptives. Resetting the adaptives will set the adaptives to factory settings.
NOTE: Perform the Coast Down Adaptations first. The Transmission Temperature must be greater than 60° C (140° F) and less than 70° C (158° F). Failure to stay within these temperature ranges will void the procedure.
2. Drive the vehicle until the transmission temperature is in the specified range.
3. Perform 4 to 5 coast downs from 5th to 4th gear and then 4th to 3rd gear.
NOTE: For Upshift adaptation, the Transmission temperature must be greater than 60° C (140° F) and less than 100° C (212° F). Failure to stay within these temperature ranges will void this procedure.
4. From a stop, moderately accelerate the vehicle and obtain all forward gear ranges while keeping the Engine RPM below 1800 RPM. Repeat this procedure 4 to 5 times.
5. Obtaining 5th gear may be difficult at 1800 RPM. Allow the transmission to shift into 5th gear at a higher RPM then lower the RPM to 1800 and perform shifts between 4th and 5th gears using the shift lever.
6. The TCM will store the adaptives every 10 minutes. After completion of the adaptation procedure make sure the vehicle stays running for at least 10 minutes.
7. It is possible to manually store the adaptives under the 10 minute time frame using the scan tool Store Adaptives procedure.
Thursday, November 26th, 2020 AT 11:23 AM
(Merged)
