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Test N: Rear Speed Sensor Input Circuit Failure

  1. DTC 1230

    Turn ignition off. Install Breakout Box (49-UN01-058) with proper overlay. Measure resistance between breakout box pins No. 21 and 22. If resistance is 800-1400 ohms, go to step 7). If resistance is not 800-1400 ohms, go to next step.

  2. Measure Rear Speed Sensor Resistance

    Disconnect rear sensor wiring harness connector. Measure resistance between sensor terminals. If resistance is 800-1400 ohms, go to next step. If resistance is not 800-1400 ohms, replace sensor and go to step 11).

  3. Check Red/Pink Wire Circuit Resistance

    Turn ignition off. Measure resistance of Red/Pink wire between breakout box pin No. 22 and rear axle sensor wiring harness connector. If resistance is not about zero ohms, repair Red/Pink wire circuit and go to step 11). If resistance is about zero ohms, circuit is okay, go to next step.

  4. Check Light Green/Black Wire Circuit Resistance

    Turn ignition off. Measure resistance of Light Green/Black wire between breakout box pin No. 21 and rear axle sensor wiring harness connector. If resistance is not about zero ohms, repair Light Green/Black wire circuit and go to step 11). If resistance is about zero ohms, circuit is okay, go to next step.

  5. Check Red/Pink Wire Circuit Short To Ground

    Turn ignition off. Leave rear sensor wiring harness connector disconnected. Check for continuity between breakout box pins No. 1 and 22. If continuity exists, repair Red/Pink wire circuit short to ground and go to step 11). If continuity does not exist, circuit is okay, go to next step.

  6. Check Light Green/Black Wire Circuit Short To Ground

    Turn ignition off. Leave rear sensor wiring harness connector disconnected. Check for continuity between breakout box pins No. 1 and 21. If continuity exists, repair Light Green/Black wire circuit short to ground and go to next step. If continuity does not exist, circuit is okay, go to step 8).

  7. Check For Internal Short

    Measure resistance between a known good ground and either terminal of rear axle speed sensor connector. If resistance is less than 10 ohms, replace sensor and go to step 11). If resistance is more than 10 ohms, go to next step.

  8. Check Sensor Wiring For Damage

    Inspect sensor wiring for damage. Repair or replace wiring as necessary and go to step 11). If wiring is okay, go to next step.

  9. Check For Intermittents

    If all previous steps have been completed, cause of condition may be wiring related. See INTERMITTENT DIAGNOSIS PROCEDURE  . Repair wiring as necessary. If wiring is okay and condition still exists, go to next step. If condition has been repaired, go to step 11) for verification of repair.

  10. Check If Steps Have Been Completed

    If this step is not completed, replacement of any system component without being instructed to do so may not correct system fault. This step requires DTC 1230 to be present, completion of all previous test steps, and affected wiring integrity verified. If all previous steps have been completed, replace rear axle speed sensor and go to next step. If all previous steps have not been completed, return to last test step completed, and continue testing.

  11. Check For DTCs

    Remove breakout box. Reconnect all connectors. Clear all codes. Turn ignition off, then on. Retrieve codes. If SYSTEM PASS is set, condition has been repaired and test is complete. If a code other than DTC 1230 is set, perform appropriate circuit test. If DTC 1230 is still set and step 9) has been completed, install Breakout Box (49-UN01-058) with proper overlay. Repeat steps 3) thru 6) while driving vehicle. Look for any change is resistance/continuity. Repair wiring as necessary. If no change is observed, go to next step.

  12. Check Wiring Harness

    The following is time consuming and should be performed only after all previous possibilities have been exhausted. Inspect entire length of Red/Pink wire and Light Green/Black wire between rear axle speed sensor connector and control module. Check for chafing or any other damage that could cause an open or shorted condition. Repair wiring as necessary. If wiring is okay, repeat step 1) while driving vehicle. If any change in resistance occurs, repair wiring as necessary.
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