B1386, B1387

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

B1386, B1387

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 right-hand rear 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 rear end of the vehicle is jacked up and the right-hand rear 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.

2 Check the mechanical details

-	Check that:

•

wheel size and tyre pressure are correct

•

there is no wheel bearing play

Fuse inspection OK?

yes

Continue with point 3.

no

Rectify the fault.

3 Check the wheel sensor signals

-	Jack up the rear end of the vehicle.

-	Take a voltage reading (mV a.c.) on the wheel sensor's connector. Connect a voltmeter to the connector pins and rotate the RH rear wheel at about 1 revolution per second. The reading obtained should be >100 mV a.c.

Is the voltage reading OK?

yes

Continue with point 4.

no

Change the wheel sensor.

4 Check the wheel sensor's resistance

-	Unplug the control module's connector.

-	Take a resistance reading across pins 9 and 10 of the control module's connector. The resistance should be 0.8-1.7 kohms.

Is the resistance reading correct?

yes

Final check

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.