P1831

P1831
Transmission downshifting faulty

Fault symptoms
CHECK GEARBOX warning lamp on.
TCM in Limp-Home mode.

Conditions
The difference between engine speed and the transmission's input shaft speed is greater than 100 rpm for 10 seconds.
Diagnosis will not be performed if:
- The engine is idling or running at more than 4000 rpm.
- DTC P1817 has been generated.
- Less than 5 seconds has elapsed since shifting occurred.






Diagnostic procedure

1 Check the fault symptom
Check the problem by driving the car as shown in the road test schedule, see Fault diagnosis, general, "Road test schedule." Note any fault symptoms. Road Test Schedule

Are there any fault symptoms?
YES
Continue with Fault diagnosis, fault symptoms, "Mechanical and hydraulic faults," and then step 2. Non-Trouble Code Procedures

NO
Continue with step 2.






2 Final check
- Clear all diagnostic trouble codes in the system.
- Perform a driving cycle:
- Drive the car at varying loads and engine speeds for 5 minutes.
- Evaluate the driving cycle:
- Make sure the trouble code has not recurred.

Has the trouble code recurred?
YES
Continue with Fault diagnosis, general, "Before changing a control module." Tech 2 Scan Tool

NO
The steps taken to rectify the fault were correct.