Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P0812 : Reverse Position Switch CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Reverse Switch Signal | P0812 | 1 | 1 | -- |
Ground | -- | 1 | 1 | -- |
1. Backup Lamps Malfunction | ||||
Circuit/System Description
The reverse gear switch is a normally open switch that closes with the reverse gear engagement. When the switch is open the engine control module (ECM) should detect a high signal voltage input. When the switch is closed the ECM should detect a low signal voltage input.
Conditions for Running the DTC
| • | No VSS faults exist. |
| • | Reverse switch is ON. |
Conditions for Setting the DTC
The ECM detects circuit failure of the reverse input switch.
Action Taken When the DTC Sets
DTC P0812 is type C DTC.
Conditions for Clearing the DTC
DTC P0812 is type C DTC.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Exterior Lighting Systems Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, observe the scan tool Reverse Switch parameter. The reading should be Off and change to On when the transmission is shifted into reverse.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the reverse switch.
- Ignition OFF, test for less than 1 ohm between the ground circuit terminal 1 and ground.
- Ignition ON, verify the scan tool Reverse Switch parameter is Off.
- Ignition ON, install a 3-amp fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool Reverse Switch parameter is On.
- If all circuits test normal, test or replace the reverse switch.
| ⇒ | If greater than the specified value, test the ground circuit for an open/high resistance. |
| ⇒ | If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the ECM. |
| ⇒ | If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for the ECM replacement, setup, and programming
