P1822

P1822
Speed sensor, transmission output speed, control module input absent

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

Conditions
No signal from the output shaft speed sensor when:
- Car speed is higher than 4 km/h.
- Selector lever position sensor in position D, 3, 2 or 1.
- Fluid temperature higher than 20°C.

Diagnostic help
A reading of the output shaft speed can be obtained with the diagnostic instrument.
- Select "Output Shaft Speed"

Compare the diagnostic instrument reading with the speedometer when driving the car.

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 (yellow lead) in the 2-pin female connector.
The test lamp should light up.

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






2 Check the control module input for the output shaft speed.
- Turn off the ignition.
- Measure the resistance between pin 2 and the 2-pin female connector. The resistance should be 6.0-6.6 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 1 and the control module pin 30 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.