P0573

P0573-HIGH VOLTAGE DETECTED AT THE BRAKE SWITCH

P0573 - High Voltage Detected At The Brake Switch:

WHEN MONITORED
While the ignition is on.

SET CONDITION
The brake switch status is = to ON and the not brake switch status is = to OFF for a calibrated amount of time.

POSSIBLE CAUSES
- Damaged wiring harness or connectors
- Brake switch circuit open (brake switch will always be on)
- Brake switch circuit shorted to battery voltage (brake switch will always be on)
- Brake switch
- ECM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

1. BRAKE SWITCH CIRCUIT OPEN





Turn the ignition off.
Disconnect the brake switch connection. Inspect the pins and connector for damage, corrosion, etc.
Disconnect the ECM connectors. Inspect the pins and connector for damage, corrosion, etc.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between the brake switch signal circuits in the ECM connector and the brake switch connector.

Q: Is the resistance less than 10 ohms?

YES: Go To 2
NO: Repair the open brake switch circuits. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

2. BRAKE SWITCH CIRCUIT SHORTED TO VOLTAGE





Measure the voltage between the brake switch circuits in the ECM connector and battery negative.

Q: Is the voltage less than 1 volt?

YES: Go To 3
NO: Repair the open circuit. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

3. ECM
Reconnect the ECM connectors.
Install a jumper wire in the brake switch connector between signal circuit and to ground.
Turn the ignition on.
Cycle the brake pedal several times.
Using the scan tool, read the DTC's.

Q: Is the DTC for brake switch low voltage present?

YES: Go To 4
NO: Replace the ECM. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

4. BRAKE SWITCH
Reconnect the brake switch connector.
Using the scan tool, clear the DTC's.
Turn the ignition on.
Cycle the brake pedal several times.
Using the scan tool, read the DTC's.

Q: Has the brake switch High DTC returned?

YES: Replace the brake switch. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
NO: Perform Intermittent condition test.