Power Mode Mismatch
Power Mode Mismatch
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.
Circuit/System Description
The body control module (BCM) controls the ignition main relay through the control circuit by applying voltage to the ignition main relay control circuit. The ignition main relay is energized when the ignition switch is in the ACCESSORY or the ON position.
Diagnostic Aids
A short to voltage on the ignition main relay coil control will cause the engine to remain running after the mode is changed to OFF.
Reference Information
Schematic Reference
* Power Distribution Schematics Power Distribution Schematics
* Power Moding Schematics Power Moding Schematics
Connector End View Reference
Component Connector End Views Sunshade - Left (D61)
Description and Operation
Power Mode Description and Operation Power Mode
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. Verify that the device turns on and off when commanding the appropriate ignition relay ON and OFF with a scan tool.
• If the KR73 ignition main relay does not change
Refer to Circuit/System Testing - Diagnostic A.
• If the KR75 engine controls ignition relay does not change
Refer to Circuit/System Testing - Diagnostic B.
• If the KR70 auxiliary power relay does not change
Refer to Circuit/System Testing - Diagnostic C.
• If the ignition relay's change
3. All OK.
Circuit/System Testing
Diagnostic A
1. Ignition OFF and all vehicle systems OFF, disconnect the KR73 ignition main relay. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 ohms between the ground circuit terminal 1 and ground.
• If 10 ohms or greater
1. Ignition OFF.
2. 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 10 ohms
3. Ignition ON.
4. Verify a test lamp illuminates between the B+ circuit terminal 3 and ground.
• If the test lamp does not illuminate and the circuit fuse is OK
1. Ignition OFF.
2. Test for less than 2 ohms in the B+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is OK and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF.
2. Test for infinite resistance between the ignition circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the KR73 ignition main relay.
• If the test lamp illuminates
5. Connect a test lamp between the control circuit terminal 2 and the ground circuit terminal 1.
6. Verify the test lamp turns ON and OFF when commanding the run/crank relay ON and OFF with a scan tool.
• If the test lamp is always OFF
1. Ignition OFF, disconnect the harness connector at the K9 body control module.
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K9 body control module.
• If the test lamp is always ON
1. Ignition OFF, disconnect the harness connector at the K9 body control module, ignition ON.
2. Test for less than 1 V between the control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K9 body control module.
• If the test lamp turns ON and OFF
7. Verify that a test lamp does not illuminate between the ignition circuit terminal 5 and ground.
• If the test lamp illuminates
Repair the short to voltage on the ignition circuit.
• If the test lamp does not illuminate
8. Ignition ON, connect a 3 A fused jumper wire between the B+ circuit terminal 3 and the ignition circuit terminal 5.
9. Verify the device is activated.
• If the device does not activate
1. Ignition OFF, disconnect the harness connector at the device.
2. Test for infinite resistance between the ignition circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the ignition circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the device.
• If the device activates
10. Test or replace the KR73 ignition main relay.
Diagnostic B
1. Ignition OFF and all vehicle systems OFF, disconnect the KR75 engine controls ignition relay, ignition ON.
2. Verify a test lamp illuminates between the B+ circuit terminal 3 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF.
2. Test for less than 2 ohms in the B+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, test or replace the KR75 engine controls ignition relay.
• If the test lamp illuminates
3. Verify a test lamp illuminates between the B+ circuit terminal 2 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF.
2. Test for less than 2 ohms in the B+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If the test lamp illuminates
4. Connect a test lamp between the B+ circuit terminal 2 and the control circuit terminal 1.
5. Verify the test lamp turns ON and OFF when commanding the engine controls ignition relay ON and OFF with a scan tool.
• If the test lamp is always OFF
1. Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON.
2. Test for less than 1 V between the control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V
3. Ignition OFF.
4. Test for less than 2 ohms in the control 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 test lamp is always ON
1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
2. Test for infinite resistance between the control circuit 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 test lamp turns ON and OFF
6. Verify a test lamp does not illuminate between the ignition circuit terminal 5 and ground.
• If the test lamp illuminates
Repair the short to voltage on the circuit.
• If the test lamp does not illuminate
7. Ignition ON, connect a 3 A fused jumper wire between the B+ circuit terminal 3 and the ignition circuit terminal 5.
8. Verify device is activated.
• If the device does not activate
1. Ignition OFF, disconnect the harness connector at the device.
2. Test for infinite resistance between the ignition circuit terminal 5 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the ignition circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the device.
• If the device activates
9. Test or replace the KR75 engine controls ignition relay.
Diagnostic C
1. Ignition OFF and all vehicle systems OFF, disconnect the KR70 auxiliary power relay. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 ohms between the ground circuit terminal 1 and ground.
• If 10 ohms or greater
1. Ignition OFF.
2. 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 10 ohms
3. Ignition ON.
4. Verify a test lamp illuminates between the B+ circuit terminal 3 and ground.
• If the test lamp does not illuminate and the circuit fuse is OK
1. Ignition OFF.
2. Test for less than 2 ohms in the ignition circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is OK and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF.
2. Test for infinite resistance between the ignition circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the KR70 auxiliary power relay.
• If the test lamp illuminates
5. Connect a test lamp between the control circuit terminal 2 and the ground circuit terminal 1.
6. Verify the test lamp turns ON and OFF when commanding the accessory/retained accessory power relay ON and OFF with a scan tool.
• If the test lamp is always OFF
1. Ignition OFF, disconnect the harness connector at the K9 body control module.
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K9 body control module.
• If the test lamp is always ON
1. Ignition OFF, disconnect the harness connector at the K9 body control module, ignition ON.
2. Test for less than 1 V between the control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K9 body control module.
• If the test lamp turns ON and OFF
7. Verify that a test lamp does not illuminate between the ignition circuit terminal 5 and ground.
• If the test lamp illuminates
Repair the short to voltage on the ignition circuit
• If the test lamp does not illuminate
8. Ignition ON, connect a 3 A fused jumper wire between the B+ circuit terminal 3 and the ignition circuit terminal 5.
9. Verify device is activated.
• If the device does not activate
1. Ignition OFF, disconnect the harness connector at the device.
2. Test for infinite resistance between the ignition circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the ignition circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the device.
• If the device activates
10. Test or replace the KR70 auxiliary power relay.
Component Testing
Relay Test
1. Ignition OFF, disconnect the appropriate relay.
2. Test for 70-150 ohms between terminals 1 and 2.
• If less than 70 or greater than 150 ohms
Replace the relay.
• If between 70-150 ohms
3. Test for infinite resistance between the terminals listed below:
* 3 and 2
* 3 and 5
* 3 and 1
* 1 and 5
• If less than infinite resistance
Replace the relay.
• If infinite resistance
4. Test for less than 5.0 ohms between terminals 3 and 5.
• If 5.0 ohms or greater
Replace the relay.
• If less than 5.0 ohms
5. Install a 3 A fused jumper wire between relay terminal 1 and 12 V. Install a jumper wire between relay terminal 2 and ground.
6. Test for less than 5.0 ohms between terminals 3 and 5.
• If 5.0 ohms or greater
Replace the relay.
• If less than 5.0 ohms
7. All OK
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)
* Control Module References Control Module References for the appropriate module replacement, programming and setup