P0571
P0571-BRAKE SWITCH 1 PERFORMANCE
Special Tools:
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
The brake switch rationality checks both failure modes of the brake switch. The brake switch stuck on test checks for a high vehicle speed condition where the brake switch is unexpectedly depressed. The brake switch stuck off test checks for repeated vehicle stop maneuvers without the brake switch depressed.
- 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 Lamp Switch Output circuit is applied the fault will mature in 60ms. One Trip Fault.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
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 Switch No.2 circuit are not switched at the harness connector.
1. Ignition on, engine not running.
2. With the scan tool, select View DTCs.
Is the DTC Active at this time?
Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test
2. (B15) BRAKE SWITCH NO.1 SIGNAL SHORTED TO GROUND
1. Turn the ignition off.
2. Disconnect the Stop Lamp Switch harness connector.
3. Disconnect the C3 PCM harness connector.
4. 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 the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 3
3. (B16) BRAKE SWITCH NO.2 SIGNAL CIRCUIT 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 the PCM Pinout Box (8815A) to perform diagnosis.
1. Measure the resistance of the (B16) Brake Switch No.2 Signal circuit from the Stop Lamp Switch harness connector to the appropriate terminal of PCM Pinout Box.
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 the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
4. (B16) BRAKE SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO GROUND
1. Measure the resistance between ground and the (B16) Brake Switch No.2 Signal circuit in the Stop Lamp Switch harness connector.
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. (Z910) GROUND CIRCUIT OPEN
1. Measure the resistance between ground and the (Z910) Ground circuit in the Stop Lamp Switch harness connector.
Is the resistance below 5.0 Ohms?
Yes
- Go To 6
No
- Repair the open in the (Z910) Ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
6. STOP LAMP SWITCH
1. Measure the resistance between the (Z910) Ground circuit terminal and the (B15) Brake Switch No.1 Signal terminal in the Stop Lamp Switch.
2. Next, measure the resistance between the (F941) Fused Ignition Switch circuit terminal and the (B16) Brake Switch No.2 Signal circuit terminal in the Stop Lamp Switch.
3. Apply and release the brake pedal while monitoring the ohmmeter.
Does the resistance change from below 5.0 Ohms to an open circuit for one or both of the measurements taken?
Yes
- Go To 7
No
- Verify that there is good pin to terminal contact in the Switch and Control Module connectors. Replace the Stop Lamp Switch if no problems were found in the connectors. Stop Lamp Switch - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
7. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Stop Lamp Switch and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Switch and Control Module connectors.
4. Perform any Technical Service Bulletins that may apply.
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. PCM/ECM/TCM Reprogramming
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.