P1572

P1572-BRAKE SWITCH STUCK ON






For a complete wiring diagram refer to: Electrical Diagrams

When Monitored
Ignition on.

Set Condition
The PCM recognizes the Brake Switch #1 is mechanically stuck in the low/on position. One Trip Fault.

Possible Causes
- (B15) BRAKE SWITCH NO. 1 SIGNAL SHORTED TO GROUND
- (B16) BRAKE SWITCH NO.2 SIGNAL OPEN
- (F202) FUSED IGNITION SWITCH OUTPUT OPEN
- STOP LAMP SWITCH
- PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test
1. ACTIVE DTC





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

NOTE: Make sure the Stop Lamp Switch is properly wired, such as (B15) Brake Switch No.1 and (B16) Brake Lamp Switch No.2 circuit are not switched at the harness connector.

Ignition on, engine not running.
With a scan tool, read DTCs.

Is the DTC active at this time?
Yes >> Go To 2
No >> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
2. (B15) BRAKE SWITCH NO.1 SIGNAL SHORTED TO GROUND





Turn the ignition off.
Disconnect the Stop Lamp Switch harness connector.
Disconnect the PCM harness connectors.
Measure the resistance between ground and the (B15) 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 (B15) Brake Switch No.1 Signal circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 3
3. (B16) BRAKE SWITCH NO.2 SIGNAL OPEN





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 (B16) Brake Switch No.2 Signal circuit from the Stop Lamp Switch harness connector and the appropriate terminal of the special tool #8815.

Is the resistance below 5.0 ohms?
Yes >> Go To 4
No >> Repair the open in the (B16) Brake Switch No.2 Signal circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
4. (B16) BRAKE SWITCH NO.2 SIGNAL SHORT TO VOLTAGE





Turn the ignition on.
Measure the voltage of the Brake Switch No.2 Signal circuit in the Stop Lamp Switch harness connector.

Does the voltmeter indicate voltage present?
Yes >> Repair the short to voltage in the (B16) Brake Switch No.2 circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 5
5. STOP LAMP SWITCH
Remove the Stop Lamp Switch.
Measure the resistance between terminals 1 and 2 of the Stop Lamp Switch.
Next, measure the resistance between terminals 3 and 4 of the Stop Lamp Switch.
Apply and release the brake pedal while monitoring the ohmmeter during both of the above steps.

Does the resistance change from below 5.0 ohms to an open circuit for one or both of the measurements taken?
Yes >> Go To 6
No >> Replace the Stop Lamp Switch.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
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 POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Replace and program the Powertrain Control Module per Service Information.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test