B1371, B1372

Symptom: ABS (ANTI LOCK) warning lamp on, no ABS function.

B1371, B1372

Fault symptom

ABS (ANTI LOCK) warning lamp on, no ABS function.

Condition

The trouble code is generated in the event of an open circuit after a maximum of 150 milliseconds both when the car is stationary and being driven.

The trouble code is generated in the event of a faulty signal after a maximum of 20 seconds at a vehicle speed of >10 km/h.

Diagnostic help

A reading of the left-hand front wheel sensor signals can be obtained on the ISAT scan tool.

-	Select “READ VALUES".

-	Select “WHEEL SPEEDS".

The current wheel speed in km/h is displayed.

If the front assembly of the vehicle is jacked up and the left-hand front wheel rotated by hand at about 1 revolution per second, the reading obtained on the ISAT scan tool should be about 5 km/h.

Diagnostic procedure

1 Check the diagnostic trouble code

-	Connect the ISAT scan tool.

-	Start the car and drive it at a steady speed. Read WHEEL SPEEDS as described under "Diagnostic help". Compare the four wheel speeds shown on the ISAT scan tool.

Is the speed of the LH front wheel inconsistent?

yes

Continue with point 2.

no

Continue with point 4.

2 Check the mechanical details

-	Check that:

•

wheel size and tyre pressure are correct

•

there is no wheel bearing play

•

the toothed wheel is not damaged

Fuse inspection OK?

yes

Continue with point 3.

no

Rectify the fault.

3 Check the toothed wheel air gap

-	Check that the air gap between the toothed wheel and the wheel sensor is 0.6 ±0.3 mm.

Is the air gap correct?

yes

Continue with point 4.

no

Rectify the fault.

4 Check the wheel sensor's resistance

-	Unplug the control module's connector.

-	Take a resistance reading across pins 4 and 5 of the control module's connector. The resistance should be 0.8-1.7 kohms.

Is the resistance correct?

yes

Continue with point 5.

no

Check the wiring and connectors between the control module and wheel sensor. Rectify if necessary. If the wiring is OK, change the wheel sensor.

5 Final check

-	Clear the diagnostic trouble code.

-	Drive the car at varying engine loads and rpm for 5 minutes.

-	Read the diagnostic trouble code.

Is the diagnostic trouble code stored?

yes

Continue with

no

The diagnostic procedure carried out was correct or the fault is of an intermittent nature.