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Code 51 - Inhibitor Switch - A/T

NOTE: Refer to illustration for ECU connector and terminal identification. See Figure -Figure .
  1. Turn ignition on. Measure voltage between ECU connector E29, terminal No. 16 (backprobe) and ground. In Park or Neutral, 10-14 volts should be present. In all other positions, zero volts should be present. If voltages are not to specification, go to next step. If voltages are to specification, repair ECU harness or connector. If harness and connector are okay, replace ECU.
  2. Turn ignition off. Disconnect ECU and transmission harness 12-pin connector. Measure resistance between transmission harness 12-pin connector terminals No. 1 (Light Green/Yellow wire), No. 3 (Blue/Orange wire), and ECU connector E29, terminal No. 16. Less than 10 ohms should be present in both cases. Measure resistance between ECU connector E29, terminal No. 16 and ground. Minimum of one megohm should be present.
  3. If resistances are not to specification, repair or replace harness. If resistances are to specification, check and repair inhibitor switch and wiring as necessary.
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