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Code 51 - Inhibitor Switch - A/T

NOTE: Refer to illustration for ECU connector and terminal identification. See Figure .
  1. Turn ignition on. Measure voltage between ECU connector B58, terminal No. 10 (backprobe) and ground. With transmission in Neutral, zero volts should be present. With transmission in any position except Neutral, minimum 8 volts should be present. If voltages are not to specification, go to next step. If voltages are to specification, check for poor contact at ECU connector terminals. If connector terminals are okay, replace ECU.
  2. Disconnect 12-pin inhibitor switch connector. Measure resistance between inhibitor switch terminals No. 1 (Light Green/Yellow wire) and No. 4 (Black/Blue wire). With transmission in Neutral, zero ohms should be present. With transmission in any range except Neutral, minimum of one megohm should be present. If resistances are to specification, go to next step. If resistances are not to specification, adjust inhibitor switch neutral position.
  3. Disconnect ECU and inhibitor switch connectors. Measure resistance between ECU connector B58, terminal No. 10 and inhibitor switch connector terminal No. 1. Zero ohms should be present. Measure resistance between inhibitor switch connector terminal No. 1 (Light Green/Yellow wire) and ground. At least one megohm should be present. Measure resistance between inhibitor switch connector terminal No. 4 (Black/Blue wire) and ground. Zero ohms should be present.
  4. If resistances are not to specification, repair harness or connector as necessary. If resistances are to specification, repair poor terminal contact at ECU or replace ECU.
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