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Harness Inspection

  1. Measure sensor power supply voltage. Disconnect sensor harness connector. Turn ignition on. Using DVOM, measure voltage between vehicle ground and terminal No. 2 (Yellow/Red wire). Voltage should be 4.5-4.9 volts. If voltage is within specification, go to step 3. If voltage is not within specification, go to step 2.
  2. Turn ignition off. Disconnect ECM harness connector. Connect jumper wire between ECM harness connector terminal and vehicle ground. See CTS INPUT TERMINAL ID  table for ECM terminal number. Using ohmmeter, check continuity between vehicle ground and sensor harness connector terminal No. 1 (Black wire). If continuity does not exist, inspect and repair circuit. If continuity exists, substitute ECM with known good unit and retest. Go to step 3.
    CTS INPUT TERMINAL ID (1)

    Application ECM Terminal Number Connector Number Wire Color
    California 21 C50-5 Yellow/Red
    Federal 17 C50-1 Yellow/Red
    (1) See Figure and Figure .
  3. Check continuity of sensor to ECM ground circuit. Ensure ignition is off. Using ohmmeter, check resistance between sensor harness connector terminal No. 1 (Black wire) and vehicle ground. If continuity does not exist, inspect and repair circuit as needed.
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