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Test Th: Reverse Switch: Testing

    NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  1. 1) For Continuous Memory Only DTC P0812: Check Reverse Switch Function
    DTC P0812 is set when PCM senses high voltage on RS circuit when voltage should be low. Possible causes are:
    • Gearshift Lever Not In Neutral While Performing KOEO Self-Test
    • RS Circuit Shorted To B+ Or VPWR
    • Faulty RS Switch
    • RS Circuit Open Or Shorted To SIG RTN
    • Faulty Powertrain Control Module (PCM)

    Ensure gearshift lever is in Neutral during KOEO self-test. Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. Using scan tool, access RS PID from PID/DATA MONITOR & RECORD menu. Move gearshift lever in and out of Reverse. If RS PID does not change from ON to OFF with gearshift lever movement, go to next step. If RS PID value changes from ON to OFF with gearshift lever movement, concern is intermittent. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. If connector and terminals are okay, replace PCM.

  2. 2) Check RS Switch Resistance

    Disconnect RS switch connector. RS switch is located near shift linkage. Inspect switch and bracket for damage. Repair as necessary. Using a DVOM, measure resistance between RS switch terminals with gearshift lever in Reverse. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, replace RS switch.

  3. 3) Check RS Circuit For Open In Harness

    Turn ignition switch to OFF position. Disconnect scan tool from DLC. Disconnect PCM connector(s). Using a DVOM, measure resistance of RS and SIG RTN circuits between PCM harness connector and RS switch harness connector. See WIRING DIAGRAMS . If both resistances are less than 5 ohms, go to next step. If either resistance is 5 ohms or more, repair open in affected circuit.

  4. 4) Check RS Circuit For Short To SIG RTN Or Chassis Ground In Harness

    Using a DVOM, measure resistance between RS circuit, and SIG RTN circuit at PCM harness connector and chassis ground. If both resistances are more than 10 k/ohms, replace PCM. If either resistance is 10 k/ohms or less, repair RS circuit for short to chassis ground or SIG RTN.
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