Clutch does not engage
Fault symptom
When driving off in 1st or 2nd gear the clutch does not engage.
The SID unit displays "SHIFT DOWN".
The "CHECK ACS" warning lamp does not light up.
Condition
The system records an incorrect gear position.
Diagnostic help
By unplugging the gear selector position sensor's connector the car can be driven in 1st and 2nd gear also.
Warning
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If the car has to be driven with a defective or disconnected gear selector position sensor, the engine must not be started unless the gear lever is in neutral.
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Disconnection of the gear selector position sensor causes diagnostic trouble code P1700 to be generated and the Limp-Home program to be activated.
Diagnostic procedure
1 Check the voltages
Connect the Scan tool diagnostics instrument and select "GEAR POS-LENGTHW." and "GEAR POS-CROSSWISE" in the "READ FUNCTIONS" menu. Check that the voltage readings for each gear are the same as the values for pins 27 and 28 in the "Test readings, control module connections" table.
All readings OK?
Carry out calibration, see
, and continue with point 2.
Change the gear selector position sensor, see
, and continue with point 2. Remember that the gear selector position sensor is an extremely sensitive piece of equipment and can easily be damaged when fitted in place, so follow the fitting instructions carefully. Finish off by calibrating the gear positions by means of the Scan tool diagnostics instrument.
2 Final check
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Clear the diagnostic trouble code.
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Perform a drive cycle by driving the car at varying engine rpm and loads for 5 minutes.
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Check whether the symptoms have recurred.
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Have the symptoms recurred?
Continue as described in the section "Before replacing a control module", see
.
The steps taken to rectify the fault were correct.
