P1817

P1817
Speed sensor, transmission input speed, control module input absent

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

Conditions
No signal from the input shaft speed sensor when:
- The speed of the car in first gear is higher than 7 km/h
- The speed of the car in second gear is higher than 13 km/h
- The speed of the car in third gear is higher than 18km/h
- The speed of the car in fourth gear is higher than 26 km/h
- Selector lever position sensor in position D, 3, 2 or 1
- Engine speed above 400 rpm

Diagnostic help
A reading of the input shaft speed can be obtained with the diagnostics instrument.
- Read "Input shaft speed."

With the selector lever in position P or N, the diagnostics instrument should show the same rpm as indicated on the tachometer.

Check the wiring
Jiggle the wiring harness at several points and in different directions to reveal intermittent breaks and short circuits in the various leads. Observe the multimeter, test lamp or diagnostic instrument while carrying out this check.






Diagnostic procedure

1 Check the speed sensor ground connection
- Unplug the 2-pin speed sensor connector.
- Connect a test lamp between B+ and pin 2 (green lead) in the 2-pin female connector.
The test lamp should light up.

All OK?
YES
Continue with step 2.
NO
Rectify the relevant lead and continue with step 3, final check.






- Check the control module input for input speed.
- Turn off the ignition.
- Measure the resistance between the two pins in the 2-pin female connector.
The resistance should be 2.0-2.4 k ohm

All OK?
YES
Change the speed sensor and continue with step 3, final check.
NO
Rectify the relevant lead between the speed sensor pin 2 and the control module pin 12, and continue with step 3, final check.






3 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 "Before changing a control module," see Fault diagnosis, general, "Before changing a control module." Tech 2 Scan Tool

NO
The steps taken to rectify the fault were correct.