Diagnostic Test

1. Perform any Service Bulletins that may apply.
2. Turn the ignition on.
3. With the scan tool, read ABS DTCs and record on the repair order.
4. With the scan tool, read and record the Environmental Data to help identify the conditions in which the DTC was set.
5. With the scan tool, erase the DTCs.
6. Start the engine.
7. Slowly press the brake pedal and release.
8. With the scan tool, read ABS DTCs and record on the repair order.

   Is the DTC active?

   Yes 

   • Go To  2

   No 

   • Perform the ABS-INTERMITTENT CONDITION TEST. Refer to ABS INTERMITTENT CONDITION .

1. Refer to the recorded DTCs.

   Are there any other Vacuum related DTCs active?

   Yes 

   • Perform the appropriate diagnostic procedures before continuing with this test. Refer to DTC INDEX (1 OF 2) and/or DTC INDEX (2 OF 2) .

   No 

   • Go To  3

1. Turn the ignition off.
2. Visually inspect the BPP Sensor for Improper installation, damage or mechanical failure. Refer to SENSOR, STOP LAMP, REMOVAL AND INSTALLATION .

   Were any problems found?

   Yes 

   • Repair as necessary.
   • Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .

   No 

   • Go To  4

1. Turn the ignition off.
2. Isolate the circuit by disconnecting the ABS Module harness connector and the BPP Sensor harness and connector. Note:  Use the wiring diagram as a guide to follow the path of the circuit.
3. Turn the ignition on.
4. Using a DVOM, measure the voltage of the circuit being tested at the component harness connector.

Is there any voltage present?

Yes 

• Repair the circuit for a short to voltage. Use the wiring diagram as a guide to trace the circuit and look for any in-line connectors to help isolate the location of the short.
• Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .

No 

• Go To  5

1. Turn the ignition off.
2. Isolate the circuit by disconnecting the ABS Module harness connector and the BPP Sensor harness and connector. Note:  Use the wiring diagram as a guide to follow the path of the circuit.
3. Turn the ignition on.
4. Using a DVOM, measure the voltage of the circuit being tested at the component harness connector.

Is there any voltage present?

Yes 

• Repair the circuit for a short to voltage. Use the wiring diagram as a guide to trace the circuit and look for any in-line connectors to help isolate the location of the short.
• Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .

No 

• Go To  6

1. Turn the ignition off.
2. Isolate the circuit by disconnecting the ABS Module harness connector and the BPP Sensor harness and connector. Note:  Use the wiring diagram as a guide to follow the path of the circuit.
3. Turn the ignition on.
4. Using a DVOM, measure the voltage of the circuit being tested at the component harness connector.

Is there any voltage present?

Yes 

• Repair the circuit for a short to voltage. Use the wiring diagram as a guide to trace the circuit and look for any in-line connectors to help isolate the location of the short.
• Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .

No 

• Go To  7

1. The ignition must be off when checking for a short between circuits.
2. Isolate the circuit by disconnecting the ABS Module harness connector and the Vacuum Pressure Sensor harness connector. Note:  Use the wiring diagram as a guide to follow the path of the circuit.
3. Connect the test leads of the DVOM and check for continuity between the circuits being tested at the component harness connector.

Is there continuity between the circuits?

Yes 

• Repair the short between the circuits. Use the wiring diagram as a guide to trace the circuit and look for any in-line connectors to help isolate the location of the short.
• Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .

No 

• Go To  8

1. Turn the ignition off.
2. Disconnect the harness connector at the component of the circuit being tested. Note: The ECU harness connector should still be connected during this test step.
3. Turn the ignition on.
4. Set the DVOM to measure DC voltage.
5. Measure the voltage at the BPP Sensor harness connector between the (B237) Brake Pedal Position Sensor Feed and the (B937) Brake Pedal Position Sensor Return.

1. Turn the ignition off.

   Does the circuit have the proper voltage present?

   Yes 

   • Replace the Brake Pedal Position (BPP) Sensor in accordance with the Service Information. Refer to SENSOR, STOP LAMP, REMOVAL AND INSTALLATION .
   • Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .

   No 

   • Go To  9

1. Disconnect the ABS Module harness connector.
2. Disconnect all related in-line harness connections (if equipped).
3. Disconnect the related component harness connectors.
4. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
   • Proper connector installation.
   • Damaged connector locks.
   • Corrosion.
   • Other signs of water intrusion.
   • Weather seal damage (if equipped).
   • Bent terminals.
   • Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
   • Terminals that have been pushed back into the connector cavity.
   • Perform a terminal drag test on each connector terminal to verify proper terminal tension.

   Repair any conditions that are found.

5. Connect the ABS Module harness connector. Be certain that the harness connector is fully seated and the connector lock is fully engaged.
6. Connect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
7. Connect the related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. With the scan tool, erase DTCs.
   WARNING:

   To avoid possible serious or fatal injury, check brake capability is available before road testing.

9. Using the recorded Event and Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
10. With the scan tool, read ABS Module DTCs.

    Did the DTC return?

    Yes 

    • Replace the Anti-lock Brake System (ABS) Module in accordance with the Service Information. Refer to MODULE, ANTI-LOCK BRAKE SYSTEM (ABS), REMOVAL AND INSTALLATION .
    • Perform ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .

    No 

    • Perform ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
    • Test complete.