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DTC C1234: Left Rear Wheel Speed Sensor Circuit Open Or Shorted

WARNING: This page is about a different car, the 1997 Oldsmobile Cutlass and 1997 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK  . After performing diagnostic system check, go to next step.
  2. Turn ignition off. Spray left rear wheel speed sensor jumper harness thoroughly with a 5 percent saltwater solution (2 teaspoons of salt to 12 ounces of water). Disconnect EBCM connector. Using DVOM, measure resistance between speed sensor signal high circuit and speed sensor signal low circuit of EBCM connector. See WIRING DIAGRAM  . If resistance is 1530-1870 ohms at 68°F (20°C), go to next step. If resistance is not 1530-1870 ohms at 68°F (20°C), go to step 8).
  3. Using DVOM, measure resistance between speed sensor signal high circuit of EBCM connector and ground. See WIRING DIAGRAM  . If resistance is infinite, go to next step. If resistance is not infinite, go to step 12).
  4. Turn ignition on. Using DVOM, measure voltage between speed sensor signal low circuit of EBCM connector and ground. See WIRING DIAGRAM  . If voltage is 0-1 volt, go to step 7). If voltage is not 0-1 volt, go to next step.
  5. Turn ignition off. Disconnect left rear wheel speed sensor directly at sensor connector. Connect DVOM (set to DC scale) between speed sensor signal high circuit of wheel speed sensor harness connector and ground. See WIRING DIAGRAM  . Turn ignition on. Observe and note voltage. Connect DVOM (set to DC scale) between speed sensor signal low circuit of wheel speed sensor harness connector and ground. Turn ignition on. Observe and note voltage. If voltage is greater than one volt on either circuit, go to step 13). If voltage is less than one volt on either circuit, go to next step.
  6. Malfunction is intermittent. Check all connectors and harnesses for damage which could result in an open or short when all components are connected. Repair as necessary. An intermittent may be caused by a poor connection, rubbed through wire insulation, or a broken wire inside insulation. Frequency of malfunction can be determined by using enhanced diagnostic function of scan tool. If ABS warning indicator only illuminates during moist environmental conditions (i.e. rain, snow, car washes), wheel speed sensor circuitry should be checked for signs of water intrusion. Spray suspected area with a 5 percent saltwater solution (2 teaspoons of salt to 12 ounces of water). Test drive vehicle faster than 15 MPH for at least 30 seconds over various road surfaces (i.e. bumps, turns). If DTC resets, replace suspect harness and/or sensor as necessary. Check for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wiring connections, or damaged wiring harness. Resistance of wheel speed sensor will increase with increased sensor temperature.
  7. Turn ignition off. Check EBCM harness connector for poor terminal contact, contamination or damage which could result in an open or short. Repair as necessary. Reconnect all connectors. Turn ignition on. If DTC C1234 sets as current, go to step 14). If DTC C1234 does not set as current, go to step 11).
  8. Disconnect left rear wheel speed sensor directly at sensor connector. Using DVOM, measure resistance of speed sensor signal low circuit between EBCM connector and left rear wheel speed sensor. See WIRING DIAGRAM  . If resistance is 0-2 ohms, go to next step. If resistance is not 0-2 ohms, go to step 15).
  9. Using DVOM, measure resistance of speed sensor signal high circuit between EBCM connector and left rear wheel speed sensor. See WIRING DIAGRAM  . If resistance is 0-2 ohms, go to next step. If resistance is not 0-2 ohms, go to step 16).
  10. Using DVOM, measure resistance between terminals of left rear wheel speed sensor connector. See WIRING DIAGRAM  . If resistance is 1530-1870 ohms at 68°F (20°C), go to next step. If resistance is not 1530-1870 ohms at 68°F (20°C), go to step 17).
  11. Malfunction is intermittent. Check all connectors and harnesses for damage which could result in high resistance when all components are connected. Repair as necessary. An intermittent may be caused by a poor connection, rubbed through wire insulation, or a broken wire inside insulation. Frequency of malfunction can be determined by using enhanced diagnostic function of scan tool. If ABS warning indicator only illuminates during moist environmental conditions (i.e. rain, snow, car washes), wheel speed sensor circuitry should be checked for signs of water intrusion. Spray suspected area with a 5 percent saltwater solution (2 teaspoons of salt to 12 ounces of water). Test drive vehicle faster than 15 MPH for at least 30 seconds over various road surfaces (i.e. bumps, turns). If DTC resets, replace suspect harness and/or sensor as necessary. Check for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wiring connections, or damaged wiring harness. Resistance of wheel speed sensor will increase with increased sensor temperature.
  12. Repair short to ground in speed sensor signal high circuit or in speed sensor signal low circuit between EBCM connector and left rear wheel speed sensor. After repairs, perform DIAGNOSTIC SYSTEM CHECK  .
  13. Repair short to voltage in speed sensor signal high circuit or in speed sensor signal low circuit between EBCM connector and left rear wheel speed sensor. After repairs, perform DIAGNOSTIC SYSTEM CHECK  .
  14. Replace EBCM. After repairs, perform DIAGNOSTIC SYSTEM CHECK  .
  15. Repair open or high resistance in speed sensor signal low circuit between EBCM connector and left rear wheel speed sensor. After repairs, perform DIAGNOSTIC SYSTEM CHECK  .
  16. Repair open or high resistance in speed sensor signal high circuit between EBCM connector and left rear wheel speed sensor. After repairs, perform DIAGNOSTIC SYSTEM CHECK  .
  17. Replace left rear wheel speed sensor. After repairs, perform DIAGNOSTIC SYSTEM CHECK  .
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