Warning Lamp, Brake Fluid Level

Warning Lamp, Brake Fluid Level

Fault symptoms
The brake fluid level warning lamp does not come on for 3 seconds when the ignition is switched on nor when the fluid level is too low.

Diagnostic help
The brake fluid level warning lamp can be activated with the diagnostic tool.

Check the wiring harness
Jiggle the wiring harness at several points and in different directions to detect intermittent breaks and short-circuits in the leads. Observe the multimeter, test lamp or diagnostic tool during the test.

Diagnostic procedure

1. Check the fault symptoms
- What fault symptoms does the car have?






BRAKE FLUID LAMP DOES NOT GO ON FOR 3 SECONDS WHEN IGNITION TURNED ON
- Check and replace faulty bulb.
- Go to step 6.

BRAKE FLUID LAMP DOES NOT GO ON DESPITE FLUID LEVEL BEING TOO LOW
- Go to step 2.

BRAKE FLUID LAMP IS ON CONSTANTLY, REGARDLESS OF BRAKE FLUID LEVEL
- Go to step 5.

2. Check the sensor ground connection
- Unplug connector: Brake fluid level switch: (42).






- Connect test lamp 86 11 857 to B+ and pin A of the female connector.






- The test lamp should light up.






Is the function correct?
YES
- Go to step 3.
NO
- Repair or replace the lead between pin A of the connector and grounding point G33P/G33S.
- Go to step 6.

3. Check the control module's sensor input
- Unplug connector: Main instrument unit's 20-pin connector: (540).






- Connect test lamp 86 11 857 to B+ and pin 12 of the female connector.






- The test lamp should light up.






Is the function correct?
YES
- Go to step 4.
NO
- Repair or replace the lead between pin 12 of the MIU's 20-pin connector and the brake fluid level sensor.
- Go to step 6.

4. Check the control module input with jumpered circuit
- Connect a jumper between pins A and B of the female connector.






- The test lamp should light up.






Is the function correct?
YES
- Change: Brake fluid level switch.
- Go to step 6.
NO
- Repair or replace the lead between pin 12 of the MIU's 20-pin connector and the brake fluid level sensor.
- Go to step 6.

5. Check the brake fluid level sensor.
- Unplug connector: Brake fluid level switch: (42).






- The brake fluid level warning lamp should go out.






Is the function correct?
YES
- Change: Brake fluid level switch.
- Go to step 6.
NO
- Check the lead between pin 12 of the MIU's 20-pin connector and pin A of the brake fluid level sensor for shorting to ground and repair or replace it as necessary.
- Go to step 6.

6. Final check
- Clear the diagnostic trouble codes in all systems.






- Perform a functional test.






Is the function correct?
YES
- The steps taken to rectify the fault were correct.
NO
- See Fault diagnosis, general, "Before changing a control module." Before Changing A Control Module