P0571

P0571-BRAKE SWITCH 1 PERFORMANCE

For a complete wiring diagram Refer to Diagrams/Electrical.

Theory of Operation


This diagnostic is designed to detect a faulty brake switch. The algorithm starts to run when the operator is driving above 30 mph (48 kmh) for more than 5 minutes. If after that time vehicle speed drops to below 2 mph (3 kmh) and the ECM does not detect brake activity the diagnostic will fail. The ECM will turn on the ETC lamp immediately after the diagnostic runs and fails.

- When Monitored:
Engine speed is above 30 mph (48 kmh) for more than 5 minutes

- Set Condition:
Vehicle speed is detected at 2 mph (3 kmh) without brake activity.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview


Diagnostic Test


1. OTHER DTC'S
With the scan tool, read DTC's.
Are other DTCs present?

Yes


- Troubleshoot other DTCs first.


No


- Go To 2



2. ECM
Interview customer. This fault can be set if the customer coasts to a vehicle speed below 2 mph (3 kmh) by using the parking brake or exhaust brake.
Did the customer coast to a near stop without using the service brake?

Yes


- Explain diagnostic operation to customer. Repair complete.


No


- Replace the ECM.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test