Troubleshooting

Troubleshooting

Checking the connectors








- Ignition off
- Check the connectors of the brake control module (BCM) and the brake pressure sensor for contact resistance and oxidation.
- Reinstall the components, reconnect the connectors etc.
- Ignition on
- Read off the brake system pressure for the relevant pressure sensor.
- Depress the brake pedal.
Brake pressure should increase with increased pressure on the pedal. If brake pressure increases, the malfunction was caused by contact resistance in the connectors of the control module or the pressure sensor.

Other information
- For removal of the control module connectors: Connecting the breakout box, brake control module (BCM), B8444S, B6324S Connecting the Breakout Box
- Checking wiring and terminals Checking Wiring and Terminals









Does brake pressure increase?

Yes - FAULT FOUND

No - Checking the control module

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Checking the control module








- Ignition on
- Pressure sensor connector unplugged.
- Breakout box connected.
Check the voltage feed with a voltmeter:
Check the voltage feed with a voltmeter.
For pressure sensor A, measure between #A21 and #A22 on the breakout box.
For pressure sensor B, measure between #A18 and #A19 on the breakout box.
The voltage should be approx. 5 V. If the voltage is incorrect, replace the brake control module (BCM).

Other information
- Connecting the breakout box, brake control module (BCM), B8444S, B6324S Connecting the Breakout Box
- Brake Control Module (BCM), replacing Service and Repair





Was the voltage OK?

Yes - Checking wiring and sensors

No - Verification

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Checking wiring and sensors




- Ignition off
- Connect a breakout box.
Check the cables between the pressure sensor and the brake control module (BCM) for open circuit and short circuit to ground.

For pressure sensor B, check the cables:
- between pressure sensor terminal #1 and brake control module (BCM) terminal #19 (#A19)
- between pressure sensor terminal #2 and brake control module (BCM) terminal #20 (#A20)
- between pressure sensor terminal #3 and brake control module (BCM) terminal #18 (#A18)

For pressure sensor A, check the cables:
- between pressure sensor terminal #1 and brake control module (BCM) terminal #21 (#A21)
- between pressure sensor terminal #2 and brake control module (BCM) terminal #23 (#A23)
- between pressure sensor terminal #3 and brake control module (BCM) terminal #22 (#A22)

Hint: With the ignition on and the breakout box connected, check the relevant brake pressure sensor by measuring the sensor signal:

Pressure sensor B
- between terminals #A18 and #A19 on the breakout box. The voltage should be approx. 5 V.
- between terminals #A19 and #A20 on the breakout box. The voltage should be 0.25-4.75 V depending on brake pressure.

Pressure sensor A
- between terminals #A21 and #A22 on the breakout box. The voltage should be approx. 5 V.
- between terminals #A21 and #A23 on the breakout box. The voltage should be 0.25-4.75 V depending on brake pressure.

If the voltage does not change when the brake pedal is depressed, replace the pressure sensor.

Other information
- Connecting the breakout box, brake control module (BCM), B8444S, B6324S Connecting the Breakout Box
- Pressure sensor, master cylinder, replacing Service and Repair





Was a malfunction detected?

Yes - Verification

No - No Fault Found

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Verification




Verification

Hint: After carrying out the repair, check that the malfunction has been remedied.








- Ignition off
- Reconnect the connectors, components, etc.
- Ignition on
- Read off the brake system pressure for the relevant pressure sensor.
- Push down the brake pedal.
Brake pressure should increase with increased pressure on the pedal.





Does brake pressure increase?

Yes - Troubleshooting procedure complete

No - Troubleshooting information

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Troubleshooting information




Information

Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.

Do you want to exit fault-tracing?

Yes - Exit Fault-tracing

No - Attempt New Test

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Attempt New Test - Checking the connectors

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