P0571
P0571-BRAKE SWITCH 1 PERFORMANCEP0571-Brake Switch 1 Performance:
WHEN MONITORED
Ignition on.
SET CONDITION
If the output of Brake Switch No.1 to the PCM looks like it is not applied, while Brake Switch No.2 circuit is applied the fault will mature in 60 ms. One Trip Fault.
POSSIBLE CAUSES
- (B15) Brake switch no.1 signal shorted to ground
- (B15) Brake switch no.1 signal open
- (B16) Brake switch no.2 signal shorted to ground
- (B16) Brake switch no.2 signal open
- (Z912) Ground circuit 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.
- Make sure the Stop Lamp Switch is properly wired, such as (B15) Brake Switch No.1 and (B16) Brake Lamp Switch No.2 circuits are not switched at the harness connector.
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. (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 the (B15) Brake Switch No.1 Signal circuit in the Stop Lamp Switch harness connector and ground.
Q: Is the resistance below 100 ohms?
YES: Repair the short to ground in the (B15) Brake Switch No.1 Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 3
3. (B15) BRAKE SWITCH NO.1 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 (B15) Brake Switch No.1 Signal circuit between the Stop Lamp Switch harness connector and the appropriate terminal of the special tool #8815.
Q: Is the resistance below 5.0 ohms?
YES: Go To 4
NO: Repair the open in the (B15) Brake Switch No.1 Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
4. (B16) BRAKE SWITCH NO.2 SIGNAL SHORTED TO GROUND
Turn the ignition off.
Disconnect the Stop Lamp Switch harness connector.
Disconnect the PCM harness connectors.
Measure the resistance between the (B16) Brake Switch No.2 Signal circuit in the Stop Lamp Switch harness connector and ground.
Q: Is the resistance below 100 ohms?
YES: Repair the short to ground in the (B16) Brake Switch No.2 Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 5
5. (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 between the Stop Lamp Switch harness connector and the appropriate terminal of the special tool #8815.
Q: Is the resistance below 5.0 ohms?
YES: Go To 6
NO: Repair the open in the (B16) Brake Switch No.2 Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
6. (F202) FUSED IGNITION SWITCH OUTPUT (RUN-START) OPEN
Reconnect the PCM harness connector.
Turn the ignition on.
Using a 12-volt test light connected to ground, probe the (F202) Fused Ignition Switch Output circuit in the Stop Lamp Switch harness connector.
Q: Does the test light illuminate brightly?
YES: Go To 7
NO: Repair the open in the (F202) Fused Ignition Switch Output circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
7. (Z912) GROUND CIRCUIT OPEN
Using the 12-Volt test light connected to battery voltage, probe the (Z912) Ground circuit in the Stop Lamp Switch harness connector.
Q: Does the test light illuminate brightly?
YES: Go To 8
NO: Repair the open in the (Z912) Ground circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
8. 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.
Press and release the Stop Lamp Switch while monitoring the ohmmeter during both of the above steps.
Q: Does the resistance change from below 5.0 ohms to an open circuit for one or both of the measurements taken?
YES: Go To 9
NO: Replace the Stop Lamp Switch. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
9. 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.
Q: Were there any problems found?
YES: Repair as necessary. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Replace and program the Powertrain Control Module. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test