Signal Faulty. Permanent Fault

Signal faulty. Permanent fault

Checking the connectors




- Ignition off.
- Check the connectors of the ABS control unit and the brake pressure sensor for contact resistance and oxidation, as described in Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
- Connect the connectors, install the components, etc.
- Ignition on.
- Read off the brake pressure in the braking system.
- Read off the signal voltage from the brake pressure sensor.
- Depress the brake pedal.
Signal voltage should increase with increased pedal pressure. If the brake pressure increases, the cause of the fault is contact resistance in the connector of the ABS control unit or the brake pressure sensor connector.









Does the voltage increase?

Yes - Fault Found

No - Checking the wiring and sensor

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Checking the wiring and sensor
Check the wiring between brake pressure sensor 2:
- #1 and control unit #26 (#A26)
- #2 and control unit #10 (#A10)
- #3 and control unit #41 (#A41)
for an open circuit as described in Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault , a short circuit to ground as described in Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault , and a short circuit to voltage supply as described in Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Hint: With the ignition on and the test box connected, check brake pressure sensor 2 by testing the sensor signal between
- #26 and #41 on the test box. The voltage should be approximately 5 V.
- #10 and #26 on the test box. The voltage should be between 0.25-4.75 V, depending on the brake pressure.

Do the necessary corrective action.

Additional information:
- To connect the test box, see Connecting the ABS/DSTC breakout box Pinout Values and Diagnostic Parameters.
- To replace the brake pressure sensor, see Pressure sensor, master cylinder, replacing Service and Repair.
- For information on signals, see Signal specification, ABS / DSTC (dynamic stability and traction control) control module Signal Specification.









Is there a fault?

Yes - Verification

No - No Fault Found

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Verification




Verification

Verification

Hint: After the repair it is necessary to check that the fault has been rectified.




- Ignition off.
- Connect the connectors, install the components, etc.
- Ignition on.
- Read off the brake pressure in the braking system.
- Read off the signal voltage from the brake pressure sensor.
- Depress the brake pedal.
Signal voltage should increase with increased pedal pressure.









Does the voltage increase?

Yes - VERIFIED

No - VERIFICATION FAILED

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VERIFIED - Fault Found

VERIFICATION FAILED - Trouble-shooting information

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Trouble-shooting 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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