P1842

TORQUE LIMITATION SIGNAL TO FUEL SYSTEM, OPEN CIRCUIT OR SHORTING TO GROUND.





Fault Symptom.
CHECK ENGINE indicator lamp (MIL) on.
The system's emergency operation program has been activated.
No signal for torque reduction results in harsh shifting.

Conditions.
Shorting to ground or open circuit.

Diagnostic Help.
The torque limitation function can be checked using an ISAT scan tool. Select "ACTIVATE". Select "TORQUE LIMITATION". With the selector lever in position N and the engine running under no-load conditions at more than 3,000 rpm, engine speed should drop momentarily to about 2,500 rpm and then stabilize at the former rpm figure again.

Check The Wiring.
Intermittent faults may occur as a result of temporary short circuits and breaks in the wiring. Jiggle the leads at several places and in different directions to reveal any faults in the wiring harness, including connectors. Observe the multimeter, test lamp or ISAT scan tool while carrying out this check,





Procedure.
1. Check the signal to the engine management system
- Plug a BOB into the transmission control module connector but do not connect the control module.
- Turn the ignition switch to the ON position.
- Take voltage and amperage readings across pins 13 and 22. Nominal voltage is about B+ (battery voltage) and amperage about 8 mA.

Are the test readings correct?

YES: Proceed to point 3.
NO: Continue with point 2.

2. Check The Wiring between the transmission control module and the engine control module
Check the continuity of the wiring between pin 13 of the transmission control module and pin 13 (Saab Trionic) or pin 51 (Motronic) of the engine control module.

Is the wiring OK?

YES: Continue fault diagnosis in the Engine management system and then continue with point 3.
NO: Rectify the fault and continue with point 3.

3. Final check
Clear the diagnostic trouble code. Drive the car on test at varying engine loads and speeds and 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.