C1390

C1390
Wheel Sensor. Wrong Number of Teeth

Fault symptoms
ABS warning lamp on. ABS not functioning.

Conditions
The respective wheel speed value is compared with a reference value (the filtered mean of the speed of all four wheels).
^ Speed of one wheel > 25% higher than the reference speed over 20 s.
^ Speed of two wheels >6% higher than the reference speed over 80 s.
^ Speed of one wheel <6% lower than the reference speed over 20 s. Alternatively, speed of two wheels lower over 10 s.
^ ABS modulation continuous for more than 60 s.

Diagnostic help
^ The respective wheel speed sensor signal can be read using the diagnostic tool.
- Select "Read Values".
- Select "Wheel speed".
The current wheel speed in km/h is displayed.

Diagnostic procedure
1. Checking Wheel Speeds





^ Contact ABS.
^ Drive the car at a steady speed.
^ Read value: Wheel Speed Front Left (ABS).
^ Read value: Wheel Speed Front Right (ABS).
^ Read value: Wheel Speed Rear Left (ABS).
^ Read value: Wheel Speed Rear Right (ABS).

After checking each wheel
Go to step 2

2. Checking Wheel Speeds





^ The speed readings for all four wheels should be the same.

Is the function correct?

NO
Go to step 3

YES
Go to step 28

3. Selecting The Wheel With Incorrect Wheel Speed

Wheel speed front left shows incorrect value
Go to step 4

Wheel speed front right shows incorrect value
Go to step 10

Wheel speed rear left shows incorrect value
Go to step 16

Wheel speed rear right shows incorrect value
Go to step 22

4. Checking Wheel Speed





^ Contact ABS.





^ Drive the car at a steady speed.
Go to step 5

5. Checking Wheel Speed





^ Read value - Wheel Speed Front Left (ABS).





Is the displayed FL wheel speed correct?

NO
Go to step 6

YES
Go to step 28

6. Checking Mechanical Quantities





Check that the tire pressure, wheel size, wheel-bearing play and toothed wheel are OK.

Is the function correct?

NO
Go to step 7

YES
Go to step 8

7. Checking Mechanical Quantities

Rectify the fault
When repair is complete
Go to step 28

8. Checking The Toothed Wheel Air Gap





The air gap between the toothed wheel and the sensor should be 0.3 - 1.3 mm.

Is the function correct?

NO
Go to step 9

YES
Go to step 28

9. Checking The Toothed Wheel Air Gap

Rectify the fault
When repair is complete
Go to step 28

10. Checking Wheel Speed





^ Contact ABS.





^ Drive the car at a steady speed.
Go to step 11

11. Checking Wheel Speed

^ Read value - Wheel Speed Front Right (ABS).





Is the displayed FR wheel speed correct?

NO
Go to step 12

YES
Go to step 28

12. Checking Mechanical Quantities





Check that the tire pressure, wheel size, wheel-bearing play and toothed wheel are OK.

Is the function correct?

NO
Go to step 13

YES
Go to step 14

13. Checking Mechanical Quantities

Rectify the fault
When repair is complete
Go to step 28

14. Checking The Toothed Wheel Air Gap





The air gap between the toothed wheel and the sensor should be 0.3 - 1.3 mm.

Is the function correct?

NO
Go to step 15

YES
Go to step 28

15. Checking The Toothed Wheel Air Gap

Rectify the fault
When repair is complete
Go to step 28

16. Checking Wheel Speed





^ Contact ABS.





^ Drive the car at a steady speed.
Go to step 17

17. Checking Wheel Speed

^ Read value - Wheel Speed Rear Left (ABS).





Is the displayed RL wheel speed correct?

NO
Go to step 18

YES
Go to step 28

18. Checking Mechanical Quantities





Check that the tire pressure, wheel size and wheel-bearing play are OK.

Is the function correct?

NO
Go to step 19

YES
Go to step 20

19. Checking Mechanical Quantities

Rectify the fault
When repair is complete
Go to step 28

20. Checking The Toothed Wheel Air Gap





The air gap between the toothed wheel and the sensor should be 0.3 - 1.3 mm.

Is the function correct?

NO
Go to step 21

YES
Go to step 28

21. Checking The Toothed Wheel Air Gap

Rectify the fault
When repair is complete
Go to step 28

22. Checking Wheel Speed





^ Contact ABS.





^ Drive the car at a steady speed.
Go to step 23

23. Checking Wheel Speed

^ Read value - Wheel Speed Rear Left (ABS).





Is the displayed RL wheel speed correct?

NO
Go to step 24

YES
Go to step 28

24. Checking Mechanical Quantities





Check that the tire pressure, wheel size and wheel-bearing play are OK.

Is the function correct?

NO
Go to step 25

YES
Go to step 26

25. Checking Mechanical Quantities

Rectify the fault
When repair is complete
Go to step 28

26. Checking The Toothed Wheel Air Gap





The air gap between the toothed wheel and the sensor should be 0.3 - 1.3 mm.

Is the function correct?

NO
Go to step 27

YES
Go to step 28

27. Checking The Toothed Wheel Air Gap

Rectify the fault
When repair is complete
Go to step 28

28. Final Check





^ Clear the diagnostic trouble codes in all systems.





Carry out a drive cycle:

^ Drive the car at varying engine loads and engine rpm for five minutes.

Evaluate the drive cycle.





^ Check that the diagnostic trouble code has not recurred

Is the function correct?

NO
Go to step 30

YES
Go to step 20

29. Final Check

The steps taken to rectify the fault were correct.
Diagnosis is complete


30. Final Check

Diagnosis for this fault code is complete.
Refer to "Before Changing A Control Module" at General.