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P1842

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.

P1842

Torque limitation request to the fuel system, open circuit or short circuit to ground.

Fault symptoms

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

Short circuit to ground or open circuit.

Diagnostic help

The torque limitation function can be controlled with the diagnostic tool. Select "ACTIVATE". Select "TORQUE LIMITATION". With the selector lever in position N and unladen engine running above 3000 rpm, the engine speed should momentarily drop to around 2500 rpm and then stabilize.

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.

Diagnostic procedure

1 Check the signal to the engine management system




- Connect the BOB to the transmission control module connector but without connecting the control module.

- Turn the ignition to the ON position.

- Take a voltage and current reading between pin 13 and pin 22. The nominal values are approx. B+ and approx. 8 mA respectively.


Are the readings correct?

yes

Continue with step 3.


no

Continue with step 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 as described in Service Manual 2:7 "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.

Does the diagnostic trouble code recur?

yes

Continue with .


no

The remedial action taken was correct.