Operation CHARM: Car repair manuals for everyone.

Fault In Circuit






Fault in circuit

Other diagnostic trouble codes (DTCs)
Read off other diagnostic trouble codes (DTCs).

Hint: To guarantee the correct diagnostic trouble code (DTC) status, if any of the following DTCs are stored, the DTC status must be established by a status check.





Are diagnostic trouble codes (DTCs) ABS-142, ABS-143, ABS-144 or ABS-423 stored?

Yes - Status check

No - Fault in circuit. Permanent fault Fault In Circuit. Permanent Fault

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Status check




- Start the engine to create a vacuum in the power brake booster.
- Shut off the engine.
- Ignition on.
- Push brake pedal down hard.
Read off EBD pressure switch position.









With the brake pedal up this value should read OFF. With the brake pedal fully depressed this value should read ON.

OK - Fault-trace according to Fault in circuit. Intermittent fault Fault In Circuit. Intermittent Fault.

Not OK - Fault-trace according to Fault in circuit. Permanent fault Fault In Circuit. Permanent Fault.

OK - INT

Not OK - PER

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PER





Fault in circuit. Permanent fault

Connecting breakout box and checking ground terminals





Connecting the breakout box

Connecting the breakout box




- Ignition off.
- Disconnect the ABS control module by pressing in the catch on the rear edge of the cover (wheel arch side). Carefully turn the cover upwards so that the locking catches release.
- Check control module and control module connector to ensure that: Male and female terminals are undamaged and properly attached (cannot be pressed in). Female terminal cables are correctly connected to the terminals.
- Pay particular attention to the terminals related to the diagnostic trouble code (DTC)/symptom.
- Connect adapter 951 1354 Adapter 25-pin ABS 850 951 1354 Adapter 25-Pin ABS 850 to the control module connector (wiring side) and connect breakout box 951 1428 Breakout box 951 1428 Breakout Box to the adapter.
- Control module disconnected.
- Then check ground terminals.





Continue - Checking ground terminals

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Checking ground terminals








- Ignition off.
- Switch off all equipment that takes power from the battery (courtesy lighting, radio etc).




- Connect an ohmmeter between battery negative terminal and #8 and #24 on the breakout box.

The ohmmeter should read approximately 0 ohms for all readings.

OK - Return to the fault-tracing procedure where it was interrupted.
Reading is OK

Not OK - Check ground terminal 1/1 (battery negative terminal) and cable between ground terminal and control module #8 and #24, for an open-circuit and contact resistance.-Return to the fault-tracing procedure where it was interrupted.
Value is not OK

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Reading is OK
- Return to the fault-tracing procedure where it was interrupted.

Continue - FAULT FOUND

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Value is not OK
- Check ground terminal 1/1 (battery negative terminal) and cable between ground terminal and control module #8 and #24, for an open-circuit and contact resistance.
- Return to the fault-tracing procedure where it was interrupted.

Continue - FAULT FOUND

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Then continue with:

FAULT FOUND - Checking for resistance in the EBD pressure switch circuit

FAULT-TRACING FAILED - Checking for resistance in the EBD pressure switch circuit

No Fault Found - Checking for resistance in the EBD pressure switch circuit

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Checking for resistance in the EBD pressure switch circuit








- Ignition off.
- Control module disconnected.
- Connect an ohmmeter between #5 and #7 on the breakout box.
- Start the engine to pump up a vacuum in the power brake booster.
- Switch off the engine.
- Push brake pedal down hard.
Read off the ohmmeter.









With the brake pedal up the reading should be approximately 0 ohms. With the brake pedal fully depressed the ohmmeter should read infinite resistance.

OK - Checking EBD pressure switch circuit

Not OK - Checking resistance in the EBD pressure switch

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Checking resistance in the EBD pressure switch








- Ignition off.
- Disconnect EBD pressure switch.
- Connect an ohmmeter between EBD-pressure switch connector terminals 1 and 2.
- Start the engine to pump up a vacuum in the power brake booster.
- Switch off the engine.
- Push brake pedal down hard.
Read off the ohmmeter.









With the brake pedal up the reading should be approximately 0 ohms. With the brake pedal fully depressed the ohmmeter should read infinite resistance.

OK - Checking resistance in signal cable (+)

Not OK - Replacing component

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Replacing component
Try a new EBD pressure switch.

Select "Continue" when the component has been replaced.

Continue - Verification

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Checking resistance in signal cable (+)












- Ignition off.
- EBD pressure switch disconnected.
- Control module disconnected.
Connect an ohmmeter between EBD pressure switch connector terminal 1 and #5 on the breakout box.









The ohmmeter should read approximately 0 ohms.

OK - Checking resistance in the signal cable (-)

Not OK - Checking for an open-circuit in the cable

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Checking for an open-circuit in the cable
Check cable between EBD pressure switch connector terminal 1 and control module #5 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.









Select "Continue" when the fault has been repaired.

Continue - Verification

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Checking resistance in signal cable (-)












- Ignition off.
- EBD pressure switch disconnected.
- Control module disconnected.
Connect an ohmmeter between EBD pressure switch connector terminal 2 and #7 on the breakout box.









The ohmmeter should read approximately 0 ohms.

OK - Checking signal cable (+) resistance to signal cable (-)

Not OK - Checking for an open-circuit in the cable

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Checking for an open-circuit in the cable
Check cable between EBD pressure switch connector terminal 2 and control module #7 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.









Select "Continue" when the fault has been repaired.

Continue - Verification

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Checking signal cable (+) resistance to signal cable (-)












- Ignition off.
- EBD pressure switch disconnected.
- Control module disconnected.
Connect an ohmmeter between #7 and #5 on the breakout box.









The ohmmeter should read infinite resistance.

OK - Checking for contact resistance and oxidation

Not OK - Checking for a short-circuit

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Checking for contact resistance and oxidation
The cause of the diagnostic trouble code (DTC) has been loose connections in the EBD pressure switch connector.
Check the EBD pressure switch connector for contact resistance and oxidation and remedy according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Select "Continue" when the fault has been repaired.

Continue - Verification

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Checking for a short-circuit
Check cable between EBD pressure switch connector terminal:
- 1 and control module #5
- 2 and control module #7
for a short-circuit to ground according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault









Select "Continue" when the fault has been repaired.

Continue - Verification

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Checking EBD pressure switch circuit








- Ignition off.
- Connect control module.
- Ignition on.
- Brake pedal up.
Connect a voltmeter between #5 and #8 on the breakout box.









The voltmeter should read 5-6 V.

OK - Checking for contact resistance and oxidation

Low - Checking for a short-circuit

High - Checking for a short-circuit

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Checking for contact resistance and oxidation
The cause of the diagnostic trouble code (DTC) has been loose connections in the control module connector.
Check control module connector for contact resistance and oxidation and remedy according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Select "Continue" when the fault has been repaired.

Continue - Verification

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Checking for a short-circuit
Check cable between EBD pressure switch connector terminal:
- 1 and control module #5
- 2 and control module #7
for a short-circuit to ground according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.









Select "Continue" when the fault has been repaired.

Continue - Verification

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Checking for a short-circuit
Check cable between EBD pressure switch connector terminal:
- 1 and control module #5
- 2 and control module #7
for a short-circuit to supply voltage according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.









Select "Continue" when the fault has been repaired.

Continue - Verification

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Verification

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




- Start the engine to pump up a vacuum in the power brake booster.
- Switch off the engine.
- Ignition on.
- Push brake pedal down hard.
Read off EBD pressure switch position.









With the brake pedal up this value should be OFF. With the brake pedal fully depressed this value should be ON.

OK - FAULT FOUND

Not OK - 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 - Exit fault-tracing

No - Attempt New Test

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Attempt New Test - Connecting breakout box and checking ground terminals

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No Fault Found - No Fault Found

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INT





Fault in circuit. Intermittent fault

Checking cables and terminals
Check control module and EBD pressure switch connectors for contact resistance and oxidation according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.
Check cable between EBD pressure switch connector terminal:
- 1 and control module #5
- 2 and control module #7
for an intermittent open-circuit according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults , an intermittent short-circuit to ground according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults , and an intermittent short-circuit to supply voltage according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.









Select "Continue" when the fault has been repaired.

Continue - Fault-tracing information

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Fault-tracing information




Information

Fault-tracing information
If the fault is intermittent, do not verify fault-tracing if the fault does not recur.
It is possible to view the information again, or leave fault-tracing for this diagnostic trouble code (DTC).

Do you want to view the information again?

Yes - Attempt New Test

No - FAULT FOUND

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Attempt New Test - Checking cables and terminals

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No Fault Found - No Fault Found

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