P1572
P1572 - Brake Pedal Stuck On
For wiring diagrams, refer to.
• When Monitored: With the gear selector in drive, vehicle speed more than a minimum value, and battery voltage greater than 10.4 volts.
• Set Condition: The PCM detects that the actual state of brake signal 1 or brake signal 2 does not match the desired state during monitoring.
• Always perform the pre-diagnostic troubleshooting procedure before proceeding. Refer to => Non-DTC Based Diagnostics. Pre-Diagnostic Troubleshooting Procedure
Test Step 1 - DTC is Active
• Turn the ignition ON.
• With the scan tool, monitor the brake signal 1 and brake signal 2 states while pressing and releasing the brake pedal several times.
Do the Brake Signal states change appropriately as the pedal is pressed and released?
Yes
• Refer to the checking for an intermittent DTC diagnostic procedure. Refer to => Non-DTC Based Diagnostics. Checking for an Intermittent DTC
No
• Go to Test Step 2 => [ Test
Step 2 - Brake Signal 1 Circuit ]
Test Step 2 - Brake Signal 1 Circuit
• Turn the ignition OFF.
• Disconnect the PCM connector.
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.
• Using a test lamp connected to 12 volts, check the brake signal 1 circuit at the appropriate terminal of special tool #8815 while pressing and releasing the brake pedal several times.
Does the test lamp change from illuminated to not illuminated as the brake pedal is pressed and released?
Yes
• Go to Test Step 3 => [ Test
Step 3 - Brake Signal 2 Circuit ]
No
• Go to Test Step 4 => [ Test
Step 4 - Ground Circuit Open or High Resistance ]
Test Step 3 - Brake Signal 2 Circuit
• Turn the ignition ON.
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.
• Using a test lamp connected to ground, check the brake signal 2 circuit at the appropriate terminal of special tool #8815 while pressing and releasing the brake pedal several times.
Does the test lamp change from illuminated to not illuminated as the brake pedal is pressed and released?
Yes
• Go to Test Step 11 => [ Test
Step 11 - PCM ]
No
• Go to Test Step 7 => [ Test
Step 7 - Fused Ignition Switch Output (Run-Start) Circuit Open or High Resistance ]
Test Step 4 - Ground Circuit Open or High Resistance
• Turn the ignition OFF.
• Disconnect the stop lamp switch connector.
• Using a test lamp connected to 12 volts, check the ground circuit in the stop lamp switch harness connector.
• The test lamp should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test lamp illuminated and bright?
Yes
• Go to Test Step 5 => [ Test
Step 5 - Brake Signal 1 Circuit Shorted to Ground ]
No
• Repair the ground circuit for an open or high resistance.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
Test Step 5 - Brake Signal 1 Circuit Shorted to Ground
• Measure the resistance between ground and the brake signal 1 circuit in the stop lamp switch harness connector.
Is the resistance more than 100 ohms?
Yes
• Go to Test Step 6 => [ Test
Step 6 - Brake Signal 1 Circuit Open or High Resistance ]
No
• Repair the brake signal 1 circuit for a short to ground.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
Test Step 6 - Brake Signal 1 Circuit Open or High Resistance
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 brake signal 1 circuit between the stop lamp switch harness connector and the appropriate terminal of special tool #8815.
Is the resistance less than 5.0 ohms?
Yes
• Go to Test Step 10 => [ Test
Step 10 - Stop Lamp Switch ]
No
• Repair the brake signal 1 circuit for an open or high resistance.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
Test Step 7 - Fused Ignition Switch Output (Run-Start) Circuit Open or High Resistance
• Turn the ignition OFF.
• Disconnect the stop lamp switch connector.
• Turn the ignition ON.
• Using a test lamp connected to ground, check the fused ignition switch output (Run-Start) circuit in the stop lamp switch harness connector.
• The test lamp should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test lamp illuminated and bright?
Yes
• Go to Test Step 8 => [ Test
Step 8 - Brake Signal 2 Circuit Shorted to Voltage ]
No
• Repair the fused ignition switch output (Run-Start) circuit for an open circuit or high resistance.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
Test Step 8 - Brake Signal 2 Circuit Shorted to Voltage
• Measure the voltage of the brake signal 2 circuit in the stop lamp switch harness connector.
Is there any voltage present?
Yes
• Repair the brake signal 2 circuit for a short to voltage.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
No
• Go to Test Step 9 => [ Test
Step 9 - Brake Signal 2 Circuit Open or High Resistance ]
Test Step 9 - Brake Signal 2 Circuit Open or High Resistance
• Turn the ignition OFF.
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 brake signal 2 circuit between the stop lamp switch harness connector and the appropriate terminal of special tool #8815.
Is the resistance less than 5.0 ohms?
Yes
• Go to Test Step 10 => [ Test
Step 10 - Stop Lamp Switch ]
No
• Repair the brake signal 2 circuit for an open or high resistance.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
Test Step 10 - Stop Lamp Switch
• Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the stop lamp switch and the PCM.
• Look for any chafed, pierced, pinched, or partially broken wires.
• Look for broken, bent, pushed out or corroded terminals.
• Refer to any technical service bulletins that may apply.
Were any problems found?
Yes
• Repair as necessary.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
No
• Replace the stop lamp switch.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
Test Step 11 - PCM
• Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the stop lamp switch and the PCM.
• Look for any chafed, pierced, pinched, or partially broken wires.
• Look for broken, bent, pushed out or corroded terminals.
• Refer to any technical service bulletins that may apply.
Were any problems found?
Yes
• Repair as necessary.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
No
• Replace and program the PCM.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test