P1831

TRANSMISSION DOWNSHIFTING FUNCTION FAULTY





Fault Symptom.
CHECK GEARBOX indicator lamp on. The system's emergency operation program has been activated.

Conditions.
Transmission input shaft speed on downshifting is higher than:
- 225 km/h to 3rd gear
- 132 km/h to 2nd gear
- 76 km/h to 1st gear.

Diagnostic Help.
The fault is probably a mechanical malfunction and can scarcely be due to a fault in the control system. Wear in the transmission should be investigated.





Procedure.
1. Check the fault symptoms
Check the trouble by driving the car in accordance with the test driving schedule. Make a note of any fault symptoms.

Any fault symptoms?

YES: Proceed to "Mechanical and hydraulic faults",Mechanical and Hydraulic Faults and then continue with point 2.
NO: Continue with point 2.

2. Final check

Clear the diagnostic trouble code. Drive the car on test at varying engine loads and speeds so that upshifts and downshifts through all the gears, with and without kick-down, are performed. Obtain readouts of any diagnostic trouble codes that are generated.

Has the diagnostic trouble code recurred?

YES: Continue as described under "Before Changing A Control Module". Before Changing A Control Module
NO: The remedial action taken was correct.