Signal Too Low

Signal too low

Checking the connectors

Note! When cables to the brake pressure sensors are physically interchanged when installing, troubleshoot both sensors when trouble code BCM-0130 or BCM-0133 is detected.








- Ignition off
- Check the brake control module (BCM) and the brake pressure sensor connectors. Check for contact resistance and oxidation
- Reinstall the components, reconnect the connectors etc.
- Ignition on
- Read off the pressure in the brake system from the relevant pressure sensor
- Depress the brake pedal.
The brake pressure must increase with increased pedal pressure. If the brake pressure increases the cause of the fault was probably contact resistance or oxidation in the control module or pressure sensor connectors.

Other information
- To remove the control module connector, see Connecting the breakout box, brake control module (BCM) Connecting the Breakout Box, Brake Control Module (BCM)
- Checking wiring and terminals Checking Wiring And Terminals









Does the brake pressure increase?

Yes - Fault Found

No - Checking the control module

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Checking the control module








- Ignition on
- Pressure sensor connector disconnected
- The breakout box connected.
Check the voltage supply using a voltmeter:

Pressure sensor 1
- between terminal #A21 and terminal #A22 on the breakout box.

Pressure sensor 2
- between terminal #A18 and terminal #A19 on the breakout box.
The voltage must be approximately 5 V. Replace the brake control module (BCM) if the voltage is incorrect.

Other information
- To connect the breakout box, see Connecting the breakout box, brake control module (BCM) Connecting the Breakout Box, Brake Control Module (BCM)
- To replace the control module, see Brake Control Module (BCM), replacing Brake Control Module (BCM), Replacing
- For information about signals, see Signal specification, brake control module (BCM) with DSTC (dynamic stability and traction control) Signal Specification.









Was the voltage OK?

Yes - Checking wiring and sensors

No - Verification

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Checking wiring and sensors




- Ignition off
- Connect the breakout box.
Check the wiring between the pressure sensor and the control module. Check for an open-circuit. Check for a short-circuit to ground.

For pressure sensor 1, check the wiring
- between pressure sensor terminal #1 and control module terminal #21 (#A21)
- between pressure sensor terminal #2 and control module terminal #23 (#A23)
- between pressure sensor terminal #3 and control module terminal #22 (#A22).

For pressure sensor 2, check the wiring
- between pressure sensor terminal #1 and control module terminal #19 (#A19)
- between pressure sensor terminal #2 and control module terminal #20 (#A20)
- between pressure sensor terminal #3 and control module terminal #18 (#A18).

Hint: Check the relevant brake pressure sensor by measuring the signal from the sensor, with the ignition switched on and the breakout box connected:

Pressure sensor 1
- between terminal #A21 and terminal #A22 on the breakout box. The voltage must be approximately 5 V
- between terminal #A21 and terminal #A23 on the breakout box. Voltage must be between 0.25- 4.75 V, depending on brake pressure.

Pressure sensor 2
- between terminal #A18 and terminal #A19 on the breakout box. The voltage must be approximately 5 V
- between terminal #A19 and terminal #A20 on the breakout box. Voltage must be between 0.25- 4.75 V, depending on brake pressure.

Replace the pressure sensor if the voltage does not change when the brake pedal is depressed.

Other information
- To connect the breakout box, see Connecting the breakout box, brake control module (BCM) Connecting the Breakout Box, Brake Control Module (BCM)
- To replace the pressure sensor, see Pressure sensor, master cylinder, replacing Service and Repair
- For information about signals, see Signal specification, brake control module (BCM) with DSTC (dynamic stability and traction control) Signal Specification.









Was a fault detected?

Yes - Verification

No - No Fault Found

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Verification




Verification

Verification

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








- Ignition off
- Reconnect the connectors, reinstall components etc.
- Ignition on
- Read off the pressure in the brake system from the relevant pressure sensor
- Depress the brake pedal.
The brake pressure must increase with increased pedal pressure.





Does the brake pressure increase?

Yes - VERIFIED

No - VERIFICATION FAILED

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VERIFIED - Fault Found

VERIFICATION FAILED - Fault-tracing information

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Fault-tracing 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 - FAULT-TRACING FAILED

No - Attempt New Test

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FAULT-TRACING FAILED - FAULT-TRACING FAILED

Attempt New Test - Checking the connectors

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