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Home >> Chevrolet >> 2000 >> Impala LS >> Repair and Diagnosis >> Brakes >> Traction Control >> Anti-Lock Brake System With Traction Control System - DELPHI 7 >> Diagnostic Tests >> DTC C1221: Left Front Wheel Speed Sensor Input Signal Is Zero Or DTC C1225: Left Front Excessive Wheel Speed Variation

DTC C1221: Left Front Wheel Speed Sensor Input Signal Is Zero Or DTC C1225: Left Front Excessive Wheel Speed Variation

  1. Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK  under DIAGNOSIS & TESTING. After performing diagnostic system check, go to next step.
  2. Install scan tool. Drive vehicle at a speed greater than 5 MPH. Using scan tool, observe all of the wheel speed parameters in the ABS DATA LIST. If scan tool indicate the suspect wheel speed varies from the speeds of the other wheels, go to next step. If no variation is detected, problem is intermittent. See INTERMITTENTS & POOR CONNECTIONS  under DIAGNOSIS & TESTING.
  3. Check wheel speed sensor, speed sensor harness and connectors. Repair as necessary. After repairs, go to step  11 . If no problem is found, go to next step.
  4. Disconnect wheel speed sensor connector. Check resistance across wheel speed sensor terminals. If resistance is 850-1350 ohms, go to next step. If resistance is not 850-1350 ohms, go step  9 .
  5. Manually spin wheel as fast as possible. Check AC voltage across wheel speed sensor. If voltage reading is greater than 100 millivolts, go to next step. If voltage reading is not greater than 100 millivolts, go to step  9 .
  6. Check for poor connections/terminal tension at wheel speed sensor harness connector. See INTERMITTENTS & POOR CONNECTIONS  under DIAGNOSIS & TESTING. Repair as necessary. After repairs, go to step  11 . If no problem is found, go to next step.
  7. Disconnect EBCM harness connector. Check for short between wheel speed sensor circuits. Repair as necessary. After repairs, go to step  11 . If circuit is okay, go to next step.
  8. Check for poor connections or terminal tension at EBCM harness connector. See INTERMITTENTS & POOR CONNECTIONS  under DIAGNOSIS & TESTING. Repair as necessary. After repairs, go to step  11 . If connections or terminals are okay, go to step  10 .
  9. Replace wheel speed sensor. After replacing sensor, go to step  11 .
  10. Replace EBCM. After replacing EBCM, go to next step.
  11. Using scan tool, clear DTCs. Ensure DTCs C1232-C1235 are not set, brake pedal not depressed and vehicle is not in an ABS stop. Recheck DTCs. If DTC resets, go to step  2 . If DTC does not reset, system is okay.
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