P0736-GEAR RATIO ERROR IN REVERSE

For a complete wiring diagram Refer to Section 8W.

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.

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 Causes

RELATED TRANSMISSION DTCS PRESENT

INTERMITTENT GEAR RATIO ERRORS

INTERNAL TRANSMISSION

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)

Diagnostic Test

1.DETERMINING IF RELATED TRANSMISSION DTCS ARE PRESENT

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 DTCs are present, they will cause a gear ratio error. Perform the test for Loss of Prime first if it is present.

Go To 2

2.CHECK TO SEE IF P0731 IS CURRENT

CAUTION: Do not overheat the transmission.

Did the Clutch Test pass, Input Speed remain at zero?

Yes

Go To 3

Repair internal Transmission per the Service Information. Check all of the components related to the Reverse and LR clutches. Inspect the Oil Pump and repair or replace as necessary.
Perform 42RLE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)

3.CHECK FOR INTERMITTENT OPERATION

CAUTION: Removal of the Starter Relay will prevent the vehicle from being started in gear.

WARNING: The Starter Relay must be removed from the PDC. Failure to do so can result in personal injury or death.

NOTE: Failure to remove the Starter Relay can cause a Transmission - No Response condition.

Were there any problems found?

Yes

Repair as necessary.
Perform 42RLE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)

Test Complete.