MIL ON at Low Temperature/Hard Acceleration
No: 19/09/97NASRef: WSM Section 19
ISSUE: 2
Date: 12/05/97
PRIDE V 1-19
MIL Illumination
Gearbox Fault Code 23
AFFECTED VEHICLE RANGE;
RANGE ROVER (LP) 1995-1997
SITUATION:
FALSE MIL ILLUMINATION IN COLD AMBIENT TEMPERATURES
There have been some cases in which customers have complained of a MIL illumination during low ambient temperature operation. Code retrieval reveals a DTC P1775 and a gearbox fault 23. The problem is more prevalent on 4.6L vehicles under hard acceleration. In some cases the gearbox will default to 3rd gear when the fault is present.
RESOLUTION:
REPLACE PROM IN GEMS ECM
In order to properly diagnose this fault the technician should retrieve P-Codes and Freeze Frame data and FAX a completed DTCR to LRNA. A new PROM has been developed which will eliminate this problem for each affected model year. Use the following procedure to diagnose and repair this condition.
NOTE:
The repairs outlined in this TIB are to be performed to resolve customer complaint of the symptoms described.
PARTS INFORMATION;
NOTE:
PROM sets will only be released with the approval of the GEMS Helpline.
WARRANTY CLAIMS
REPAIR PROCEDURE:
TESTBOOK
1. Hook up TestBook and follow directions to retrieve fault codes.
2. Follow basic diagnostic directions as specified by TestBook.
3. Complete a DTCR, including freeze frame data.
4. If TestBook tests do not resolve the problem, follow the procedures below.
CHECK ENGINE SETTINGS
1. With TestBook, go to GEMS Real Time Monitoring and observe Ignition Retard PWM signal. A fully warm engine should read approximately 17%.
2. A reading of 13% indicates a hard fault. If a hard fault is present, it must be repaired before continuing with this procedure.
3. Go to Gearbox Real Time Monitoring and observe the torque value input to the gearbox TCM.
4. If no problems are noted with these measurements, FAX the completed DTCR to the GEMS Helpline for authorization of PROM replacement.
5. Install the updated PROM set, reset the ECM adaptations and IACV steps to 20-25.
6. Perform Drive Cycle 'C'.