P0812
DTC P0812
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P0812 00
- Reverse Position Switch Circuit - Malfunction
Diagnostic Fault Information
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 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 vehicle speed sensor faults exist.
* Reverse switch is ON.
Conditions for Setting the DTC
The ECM detects circuit malfunction of the reverse input switch.
Action Taken When the DTC Sets
DTC P0812 00 is Type C DTC.
Conditions for Clearing the DTC
DTC P0812 00 is Type C DTC.
Reference Information
Schematic Reference
Manual Transmission Schematics Electrical Diagrams
Connector End View Reference
Component Connector End Views Sunshade - Left (D61)
Description and Operation
Transmission System Description and Operation Description and Operation
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Observe the scan tool Reverse Switch parameter. The reading should be Off and change to On when the transmission is shifted into reverse.
• If the parameter does not change from Off to On
Refer to Circuit/System Testing.
• If the parameter changes from Off to On
3. All OK.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the B16 Backup Lamp Switch.
2. Test for less than 5 ohms between the ground circuit terminal 2 and ground.
• If 5 ohms or greater
1. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 5 ohms
3. Ignition ON, transmission in neutral position.
4. Verify the scan tool Reverse Switch parameter is Off.
• If the parameter is not OFF
1. Disconnect the X3 harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the signal circuit terminal 1 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K20 Engine Control Module.
• If the parameter is OFF
5. Ignition ON, install a 3 A fused jumper wire between the signal circuit terminal 1 at the B16 Backup Lamp Switch harness connector and ground.
6. Verify the scan tool Reverse Switch parameter is On.
• If the parameter is Off
1. Disconnect the X3 harness connector at the K20 Engine Control Module.
2. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 Engine Control Module.
• If the parameter is On
7. Test or replace the B16 Backup Lamp Switch.
Component Testing
1. Ignition OFF, disconnect the harness connector at the B16 Backup Lamp Switch.
2. Test for less then 5 ohms between the signal circuit terminal 1 and the ground circuit terminal 2 at the B16 Backup Lamp Switch.
• If 5 ohms or greater
Replace the B16 Backup Lamp Switch.
• If less than 5 ohms
3. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
Control Module References Control Module References for ECM replacement, programming and setup.