P1741

P1741-GEAR RATIO ERROR IN 4 PRIME



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 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.





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

1. CHECK IF RELATED TRANSMISSION DTCS ARE PRESENT
1. With the scan tool, read 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 IF THE DTC IS CURRENT
1. With the scan tool, perform the 4th gear clutch test. Follow the instructions on the scan tool.
2. 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
1. The conditions to set this DTC are not current at this time.
2. Check the gearshift linkage adjustment.
3. Gear ratio DTC's can be set by problems in the Input and Output Speed Sensor circuits. If the vehicle passes the Clutch Test and still sets a Gear Ratio DTC, check the Speed Sensors for proper operation.
4. Remove the Ignition Switch Feed fuse from the TIPM.

CAUTION: Removal of the Ignition Switch Feed fuse from the TIPM will prevent the vehicle from being started in gear.

WARNING: The Ignition Switch Feed fuse must be removed from the TIPM. 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 EATX 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.

4. CHECK FOR RELATED PRESSURE SWITCH DTCS
1. With the scan tool, read DTC's.

Are the DTC's P0870 and/or P0871 present also?

Yes

- Replace the Transmission Solenoid/TRS Assembly.
- Perform 62TE TRANSMISSION VERIFICATION TEST 62TE Transmission Verification Test

No

- Repair internal Transmission. Check all of the components related to the OD and 2/4 clutches. Inspect the Oil Pump and repair or replace as necessary.
- Perform 62TE TRANSMISSION VERIFICATION TEST 62TE Transmission Verification Test