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DTC 143: Road Speed Signal - Circuit Fault

WARNING: This page is about a different car, the 1996 Volvo 850. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check if other DTCs are present. If no other DTCs are present and fault is permanent, go to next step. If no other DTCs are present and fault is intermittent, check instrument cluster and ABS control module connectors for poor terminal contact. Repair as necessary. If other DTCs are present, test drive vehicle with scan tool disconnected. If speedometer does not work, go to next step. If speedometer does work, check instrument cluster and ABS control module connectors for poor terminal contact. Repair as necessary.
  2. Ensure ignition is off. Disconnect ABS control module. Connect breakout box to control module connector. Remove instrument cluster. See INSTRUMENT PANEL article in the ACCESSORIES & EQUIPMENT section. Disconnect instrument cluster connector. Connect ohmmeter between breakout box pin No. 6 and instrument cluster connector terminal A3 (Yellow/Brown wire). If about zero ohms are present, go to next step. If about zero ohms are not present, check for open circuit in Yellow/Brown wire between instrument cluster connector terminal A3 and ABS control module connector terminal No. 6. Repair as necessary, then go to step 5).
  3. Connect ohmmeter between breakout box pins No. 6 and 8. If ohmmeter reads infinite resistance, go to next step. If ohmmeter does not read infinite resistance, check for a short to ground in Yellow/Brown wire between instrument cluster connector terminal A3 and ABS control module terminal No. 6. Repair as necessary.
  4. Turn ignition on. Check voltage between breakout box pins No. 6 and 8. If voltmeter reads zero volts, go to next step. If voltmeter does not read zero volts, check for short circuit to voltage in Yellow/Brown wire between instrument cluster connector terminal A3 and ABS control module terminal No. 6. Repair as necessary. Because instrument cluster can be damaged by a short circuit to voltage in signal wire, go to next step and perform speedometer diagnosis.
  5. Turn ignition off. Reconnect ABS control module and instrument cluster connectors. Raise and support front of vehicle so wheels are free. Start engine. Engage gear so front wheels begin to rotate. If speedometer operates, problem was poor contact in control module and instrument cluster connectors. If speedometer does not operate, replace instrument cluster.
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