P0573
P0573-BRAKE SWITCH #1 CIRCUIT HIGHP0573-Brake Switch #1 Circuit High:
WHEN MONITORED
Ignition on.
SET CONDITION
When the PCM recognizes Brake Switch is stuck in the high/off position. One Trip Fault. Three good trips to turn off the MIL.
POSSIBLE CAUSES
- (B15) Brake switch signal circuit open
- (Z902) Ground circuit open
- Brake lamp switch
- PCM
Diagnostic Test
1. ACTIVE DTC
Ignition on, engine not running.
With a scan tool, read DTCs.
Q: Is the DTC active at this time?
YES: Go To 2
NO: Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
2. BRAKE LAMP SWITCH OPERATION
Turn the ignition off.
Disconnect the Brake Lamp Switch harness connector.
Measure the resistance between the (Z902) Ground circuit terminal and the (B15) Brake Switch Signal circuit terminal in the Brake Lamp Switch.
Apply and release the brake pedal while monitoring the ohmmeter.
Q: Does the resistance change from below 5.0 ohms to an open circuit?
YES: Go To 3
NO: Replace the Brake Lamp Switch. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
3. (B15) BRAKE SWITCH SIGNAL CIRCUIT OPEN
Disconnect the PCM harness connectors.
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.
Measure the resistance of the (B15) Brake Switch Signal circuit from the Brake Lamp Switch harness connector to the appropriate terminal of special tool #8815.
Q: Is the resistance below 5.0 ohms?
YES: Go To 4
NO: Repair the open in the (B15) Brake Switch Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
4. GROUND CIRCUIT OPEN
Measure the resistance between the (Z902) Ground circuit and ground at the Brake Lamp Switch harness connector.
Q: Is the resistance below 5.0 ohms?
YES: Go To 5
NO: Repair the open in the (Z902) Ground circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
5. PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
If there are no possible causes remaining, view repair.
Repair
Replace and program the Powertrain Control Module. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test