When Monitored And Set Conditions
This diagnostic runs continuously when the following conditions are met:
When Monitored:
- Engine speed above 450 rpm.
- No N2 - N3 input speed sensor DTCs present.
- No gear selector lever DTC present.
- No ABS system DTCs present.
- Vehicle speed above 10 Km/h (6 mph)
- Transmission Control Module (TCM) is NOT requesting a shifting event (constant gear operation).
Set Conditions:
- When a shift event is not in progress and:
- Actual gear ratio is calculated to not be equal to the target (expected) gear ratio.
- Actual (calculated) gear is less than target (expected) gear, no plausible gear is calculated.
- Actual (calculated) turbine speed is greater than 300 rpm or calculated transmission ratio is above threshold.
- Calculated transmission ratio gradient (rate of change in calculated transmission ratio) is greater than 5000 units/sec.
| Possible Causes |
|---|
| AXLE RATIO (PINION FACTOR) PROGRAMMED INTO TCM DOES NOT MATCH ACTUAL AXLE RATIO INSTALLED INTO VEHICLE |
| LOW TRANSMISSION FLUID |
| OTHER TRANSMISSION DTCS PRESENT |
| INTERNAL TRANSMISSION FAILURE |
Always perform the NAG1 Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to NAG1 TCM - PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .