P1573

SYMPTOM
P1573-BRAKE PEDAL STUCK OFF

WHEN MONITORED
Ignition on, In plant mode passed the Applied test.

SET CONDITION
PCM recognizes the Brake Pedal could not electronically indicate the released (Off) position with both switches. If P1572 sets, P1573 will also set. One trip fault.

POSSIBLE CAUSES
- (L50) BRAKE LAMP SWITCH OUTPUT CIRCUIT SHORTED TO BATTERY VOLTAGE
- (B29) BRAKE SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO GROUND
- STOP LAMP SWITCH
- PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Scan Tool Testing and Procedures

DIAGNOSTIC TEST
1. ACTIVE DTC





Note: Make sure the Stop Lamp Switch is adjusted properly before continuing.

Ignition on, engine not running.
With a scan tool, read DTCs.
Is the DTC active at this time?
Yes>> Go To 2
No>> Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4. Powertrain Verification Test - Ver 4

2. STOP LAMP SWITCH OPERATION





Turn the ignition off.
Disconnect the Stop Lamp Switch harness connectors.
Measure the resistance between the (Z429) Ground circuit terminal and the (B29) Brake Switch No.1 Signal terminal in the Stop Lamp Switch.
Apply and release the brake pedal while monitoring the ohmmeter.
Does the resistance change from below 5.0 ohms to an open circuit when pressing and releasing the brake switch?
Yes>> Go To 3
No>> Replace the Stop Lamp Switch. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.

3. STOP LAMP SWITCH OPERATION





Measure the resistance between the (A103) Fused B+ circuit terminal and the (L50) Brake Lamp Switch Output terminal in the Stop Lamp Switch.
Apply and release the brake pedal while monitoring the ohmmeter.
Does the resistance change from below 5.0 ohms to an open circuit when pressing and releasing the Stop Lamp switch?
Yes>> Go To 4
No>> Replace the Stop Lamp Switch. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.

4. (L50) BRAKE LAMP SWITCH OUTPUT CIRCUIT SHORTED TO BATTERY VOLTAGE





Disconnect the PCM harness connectors. Ignition on, engine not running.
Measure the voltage on the (L50) Brake Lamp Switch Output circuit in the Stop Lamp Switch harness connector.
Is the voltage above 1.0 volt?
Yes>> Repair the short to battery voltage in the (L50) Brake Lamp Switch Output circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Go To 5

5. (B29) BRAKE SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO GROUND





Turn the ignition off.
Measure the resistance between ground and the (B29) Brake Switch No.1 Signal circuit in the Stop Lamp Switch harness connector.
Is the resistance below 100 ohms?
Yes>> Repair the short to ground in the (B29) Brake Switch No.1 Signal circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Go To 6

6. 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.
Were there any problems found?
Yes>> Repair as necessary. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.
No>> Replace and program the Powertrain Control Module per Service Information. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-4.