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 run, steering wheel heater, and retained accessory power relays by applying voltage to their individual relay control circuits. The ignition run relay is energized when the ignition is in the ON or the CRANK position. The steering wheel heater relay is energized when the ignition switch is in the ACCESSORY or the ON position. The retained accessory power relay is energized during all power modes, except OFF-awake and CRANK. The relay is also energized for approximately 10 minutes after shutting the ignition OFF, providing no door is opened.
The BCM also controls the battery saver relay through individual circuits by applying voltage to the battery saver set and reset circuits. The battery saver relay is a latching relay that when enabled disconnect some modules from their ignition power or memory power sources.
The Engine Control Module (ECM) controls the engine controls the ignition relay by applying voltage to the engine controls relay control circuit.
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 Fuel Pump and Level Sensor Assembly
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 KR148 Steering Wheel Heater Relay does not change
Refer to Circuit/System Testing - Diagnostic A.
• If the KR76 Retained Accessory Power Relay does not change
Refer to Circuit/System Testing - Diagnostic B.
• If the ignition relays change
3. Verify that the device turns ON and OFF when switching the ignition between ON and OFF.
• If the KR74 Ignition Run Relay does not change
Refer to Circuit/System Testing - Diagnostic C.
• If the KR75 Engine Controls Ignition Relay does not change
Refer to Circuit/System Testing - Diagnostic D.
• If the ignition relays change
4. Verify that the device turns ON and OFF when enabling and disabling the battery saver mode.
• If the KR104B Battery Saver Relay 2 does not change
Refer to Circuit/System Testing - Diagnostic E.
• If the battery saver relay changes
5. All OK.
Circuit/System Testing
Diagnostic A
1. Ignition OFF and all vehicle systems OFF, disconnect the KR148 Steering Wheel Heater 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 85 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 87 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF, remove the test lamp.
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 good and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF, remove the test lamp.
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, replace the KR148 Steering Wheel Heater Relay.
• If the test lamp illuminates
5. Connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85.
6. Verify the test lamp turns ON and OFF when commanding the Auxiliary Ignition Run Relay On and Off with a scan tool.
• If the test lamp is always OFF
1. Ignition OFF, remove the test lamp, 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, remove the test lamp, 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 30 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 10 A fused jumper wire between the B+ circuit terminal 87 and the ignition control circuit terminal 30.
9. Verify device is activated.
• If the device is not activated
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 KR148 Steering Wheel Heater Relay.
Diagnostic B
1. Ignition OFF and all vehicle systems OFF, disconnect the KR76 Retained Accessory 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 86 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 87 and ground.
• If the test lamp does not illuminate
Replace the X51A Fuse Block - Instrument Panel
• If the test lamp illuminates
5. Connect a test lamp between the control circuit terminal 85 and the ground circuit terminal 86.
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, remove the test lamp, 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, remove the test lamp, 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 30 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 40 A fused jumper wire between the B+ circuit terminal 87 and the ignition circuit terminal 30.
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 KR76 Retained Accessory Power Relay.
Diagnostic C
1. Ignition OFF and all vehicle systems OFF, disconnect the KR74 Ignition Run 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 85 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 30 and ground.
• If the test lamp does not illuminate
Replace the X50A Fuse Block - Underhood
• If the test lamp illuminates
5. Connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85.
6. Verify the test lamp turns ON and OFF when switching the ignition ON and OFF.
• If the test lamp is always OFF
1. Ignition OFF, remove the test lamp, 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 and all vehicle systems OFF, remove the test lamp, disconnect 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 87 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 40 A fused jumper wire between the B+ circuit terminal 30 and the ignition circuit terminal 87.
9. Verify the device is activated.
• If the device is not activated
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 KR74 Ignition Run Relay.
Diagnostic D
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 30 and ground.
• If the test lamp does not illuminate
Replace the X50A Fuse Block - Underhood
• If the test lamp illuminates
3. Verify a test lamp illuminates between the B+ circuit terminal 85 and ground.
• If the test lamp does not illuminate
Replace the X50A Fuse Block - Underhood
• If the test lamp illuminates
4. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
5. Verify the test lamp turns ON and OFF when switching the ignition ON and OFF.
• If the test lamp is always OFF
1. Ignition OFF, remove the test lamp, 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, remove the test lamp, 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 87 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 40 A fused jumper wire between the B+ circuit terminal 30 and the ignition circuit terminal 87.
8. Verify device is activated.
• If the device is not activated
1. Ignition OFF, disconnect the harness connector at the device.
2. Test for infinite resistance between the ignition circuit terminal 87 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 E
1. Ignition OFF and all vehicle systems OFF, disconnect the KR10BA Battery Saver Relay 2. 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 6 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 5 and ground.
• If the test lamp does not illuminate
Replace the X51A Fuse Block - Instrument Panel.
• If the test lamp illuminates
5. Connect a test lamp between the control circuit terminal 1 and ground.
6. Verify the test lamp turns ON and OFF when enabling and disabling the battery saver mode.
• If the test lamp is always OFF
1. Ignition OFF, remove the test lamp, 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, remove the test lamp, 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. Connect a test lamp between the control circuit terminal 2 and ground.
8. Verify the test lamp turns ON and OFF when enabling and disabling the battery saver mode.
• If the test lamp is always OFF
1. Ignition OFF, remove the test lamp, 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, remove the test lamp, 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
9. Verify that a test lamp does not illuminate between the ignition circuit terminal 3 and ground.
• If the test lamp illuminates
Repair the short to voltage on the ignition circuit
• If the test lamp does not illuminate
10. Ignition ON, connect a 40 A fused jumper wire between the B+ circuit terminal 5 and the ignition circuit terminal 3.
11. 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
12. Test or replace the KR10BA Battery Saver Relay 2.
Component Testing
Relay Test
1. Ignition OFF, disconnect the appropriate relay.
2. Test for 70-150 ohms between terminals 85 and 86.
• 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:
* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87
• If less than infinite resistance
Replace the relay.
• If infinite resistance
4. Test for less than 5.0 ohms between terminals 30 and 87.
• 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 85 and 12 V. Install a jumper wire between relay terminal 86 and ground.
6. Test for less than 5.0 ohms between terminals 30 and 87.
• 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 (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)
* Control Module References Control Module References for the appropriate module replacement, programming and setup