Troubleshooting

Troubleshooting ECM-P157200

Checking the status




- Ignition on
Check if the malfunction is permanent or intermittent by activating readout of brake pedal position (via CAN) and position of the brake light switch.
Check that the parameters match. Pressed brake pedal shall activate the signal from the brake light switch.
If the signals do not match, this indicates that the malfunction is permanent. If the signals match, this indicates that the malfunction is intermittent and not active right now.









Continue - Checking components and wiring

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Checking components and wiring




- Ignition on
Activate readout of brake pedal position (via CAN) and position of the brake light switch.
Check that the value for brake pedal position at unaffected brake pedal is approx. 0 % and when the pedal is fully pressed down approx. 55 % when the engine is running.
Also check that the brake light switch is activated when the pedal is pressed down.
Check the connector for the brake pedal position sensor and the brake light switch for contact resistance, loose connections and oxidation.
Check the ground cable between brake light switch and engine control module (ECM) #B41 (#C41) for short-circuit to ground, as well as open circuit.

Hint: The brake pedal position sensor's signal is sent to engine control module (ECM) from brake control module (BCM) via CAN.

Remedy as necessary.

Other information
- Connecting the breakout box, B8444S Connecting the Breakout Box
- Pedal position sensor, replacing Pedal Position Sensor, Replacing
- Stop lamp switch, replacing Service and Repair
- Checking wiring and terminals Checking Wiring and Terminals





Continue - Verification

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Verification




Verification

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








- Ignition off
- Reinstall the connectors, components etc.
- Ignition on
Activate readout of brake pedal position (via CAN) and the brake light switch signal.
Check that the value for brake pedal position at unaffected brake pedal is approx. 0 % and when the pedal is fully pressed down approx. 55 % when the engine is running.
Also check that the brake light switch is activated when the pedal is pressed down.

Hint: The brake pedal position sensor's signal is sent to engine control module (ECM) from brake control module (BCM) via CAN.





Do the values match?

Yes - Troubleshooting procedure complete

No - 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 - Checking components and wiring

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