P0792

P0792-COMPOUNDER SPEED RATIO ERROR



Theory of Operation

The transmission control system uses three speed sensors, one to measure input rpm, one to measure Transfer Speed output rpm of the main transmission assembly, and a third to measure the final transmission output rpm. These inputs are essential for proper transmission operation. Therefore, the integrity of this data is verified through system checks.

- When Monitored:
The transmission gear ratio is monitored continuously while the transmission is in gear.

- Set Condition:
If there is an excessive change in the Output RPM in any gear.





Always perform the 62TE Pre-Diagnostic Troubleshooting procedure before proceeding.Pre-Diagnostic Troubleshooting Procedure

1. DETERMINING IF RELATED TRANSMISSION DTCS ARE PRESENT
1. With the scan tool, read Transmission DTCs.
2. 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 DTCs are present, they will cause a gear ratio error. Perform the test for Loss of Prime first if it is present.
- Perform 62TE TRANSMISSION VERIFICATION TEST 62TE Transmission Verification Test

No

- Go To 2

2. CHECK TO SEE IF P0792 IS CURRENT
1. With the scan tool, record the DTC Event Data, clear the DTC and road test the vehicle.
2. Try to duplicate the conditions in which the DTC originally set using the DTC EVENT DATA recorded.

Did the DTC P0792 reset?

Yes

- Repair internal Transmission as necessary. Check all of the components related to the DC and LC clutches. Inspect the Oil Pump and repair or replace as necessary. Refer to the Service Information for the proper repair procedures.
- Perform 62TE TRANSMISSION VERIFICATION TEST 62TE Transmission Verification Test

No

- Go To 3

3. CHECK FOR INTERMITTENT OPERATION
1. The conditions to set this DTC are not current at this time.
2. Check the gearshift linkage adjustment.
3. 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.
4. Remove the Starter Relay.

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

WARNING: The Starter Relay must be removed. Failure to do so can result in possible serious or fatal injury.

5. Check the wiring and connectors for the Speed Sensors for a good connection, then perform a wiggle test using the Transmission Simulator, Miller tool #8333A and the Electronic Transmission Adapter kit.
6. 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.
7. With the scan tool, check the DTC EVENT DATA to help identify the conditions in which the DTC was set.
8. Check for Service Information Tune-ups or Service Bulletins for any possible causes that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform 62TE TRANSMISSION VERIFICATION TEST 62TE Transmission Verification Test

No

- Test Complete.