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Code 51 - Neutral Switch - M/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 position, about 8 volts should be present. With transmission in any other position, zero volts should be present. If voltages are to specification, check ECU terminals for poor contact or replace ECU. If voltages are not to specification, go to next step.
  2. Disconnect 4-pin neutral switch connector. Measure resistance between neutral switch connector terminals No. 1 (Light Green/Yellow wire) and No. 3 (Black/Red wire) while moving shift lever from Neutral to any other position. At least one megohm should be present in Neutral. Zero ohms should be present with transmission in any position but Neutral. If resistances are not to specification, replace neutral switch. If resistances are to specification, go to next step.
  3. Disconnect ECU and neutral switch connectors. Measure resistance between ECU connector B58, terminal No. 10 and neutral switch connector terminal No. 2 (Black wire). Zero ohms should be present. Measure resistance between neutral switch connector terminal No. 1 (Light Green/Yellow wire) and ground. At least one megohm should be present. Measure resistance between neutral switch connector terminal No. 2 (Black 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, check ECU terminals for poor contact. If terminals are okay, replace ECU.
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