Power Mode Mismatch

Diagnostic Instructions

Circuit/System Description

The body control module (BCM) controls the ignition main and trailer ignition power relays by applying voltage to their individual relay control circuits. The ignition main relay is energized when the ignition is in the ON or the CRANK position. The trailer ignition power relay is energized when the ignition switch is in the ACCESSORY or the ON position.

The BCM also controls the battery saver relays through individual circuits by applying voltage to the battery saver set and reset circuits. The battery saver relays are a latching relays that when enabled disconnect some modules from their ignition power or memory power sources.

The keyless entry control module controls the retained accessory power relay by applying voltage to the relay coil control circuit. The retained accessory power relay is energized during all power modes, except OFF-awake, CRANK and during transmitter authentication. The keyless entry control module will deactivate components that may cause radio frequency (RF) interference when the ignition mode switch is pressed which may result in NO REMOTE DETECTED displayed on the driver information center. The relay is also energized for approximately 10 min after shutting the ignition OFF, providing no door is opened.

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 control circuit will cause the engine to remain running after the mode is changed to OFF.

Reference Information

Schematic ReferenceConnector End View Reference

Component Connector End Views

Electrical Center Identification View Reference

Electrical Center Identification Views

Description and Operation

Power Mode Description and Operation

Electrical Information ReferenceScan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Note: The vehicle may not be equipped with all components as listed below. Use schematics to determine which ignition relay supplies the ignition feed for the appropriate devices. Use the connector end view to identify the ignition circuit terminal for each of those devices.

  1. Ignition ON.
  2. Verify that the appropriate devices controlled by the KR124 Trailer Ignition Power Relay turn ON and OFF when switching the ignition between ON and OFF.
    • If the devices do not turn ON and OFF

      Refer to Circuit/System Testing – Diagnostic A.

    • If the devices turn ON and OFF
  3. Verify that the appropriate devices controlled by the KR73 Ignition Main Relay turn ON and OFF when commanding the Run/Crank Relay On and Off with a scan tool.
    • If the devices do not turn ON and OFF

      Refer to Circuit/System Testing – Diagnostic B.

    • If the devices turn ON and OFF
  4. Verify that the appropriate devices controlled by the KR75 Engine Controls Ignition Relay turn ON and OFF when switching the ignition between ON and OFF.
    • If the devices do not turn ON and OFF

      Refer to Circuit/System Testing – Diagnostic C.

    • If the devices turn ON and OFF
  5. Verify that the appropriate devices controlled by the KR76 Retained Accessory Power Relay turn ON and OFF when switching the ignition between ON and OFF.
    • If the devices do not turn ON and OFF

      Refer to Circuit/System Testing – Diagnostic D.

    • If the devices turn ON and OFF
  6. Verify that the appropriate devices controlled by the KR104A Battery Saver Relay 1 and KR104B Battery Saver Relay 2 turn ON and OFF after enabling battery saver mode (transport mode) .
    • If the devices do not turn ON and OFF

      Refer to Circuit/System Testing – Diagnostic E.

    • If the devices turn ON and OFF
  7. All OK.

Circuit/System Testing

Diagnostic A:
  1. Ignition OFF and all vehicle systems OFF, disconnect the KR124 Trailer Ignition Power Relay. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal 86 and ground.
    • If 10 Ω or greater
    1. Ignition OFF.
    2. Test for less than 10 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω
  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 X53A Fuse Block - Rear Body

    • 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 switching the ignition between 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 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, 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 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 30 A fused jumper wire between the B+ circuit terminal 30 and the ignition control circuit terminal 87.
  9. Verify the device is activated.
    • If the device does not activate
    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
    3. Test for less than 2 Ω in the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the device.
    • If the device activates
  10. Test or replace the KR124 Trailer Ignition Power Relay.
Diagnostic B:
  1. Ignition OFF and all vehicle systems OFF, disconnect the KR73 Ignition Main Relay. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal 86 and ground.
    • If 10 Ω or greater
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω
  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 85 and the ground circuit terminal 86.
  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, 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 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, 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 circuits listed below and ground.
    • Ignition circuit terminal 87
    • Ignition circuit terminal 87A
    • 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 circuits listed below.
    • Ignition circuit terminal 87
    • Ignition circuit terminal 87A
  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 Ω in the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the device.
    • If the device activates
  10. Test or replace the KR73 Ignition Main Relay.
Diagnostic C:
  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 between 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 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, 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 does not activate
    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 Ω in the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the device.
    • If the device activates
  9. Test or replace the KR75 Engine Controls Ignition Relay.
Diagnostic D:
  1. Ignition OFF and all vehicle systems OFF, disconnect the KR76 Retained Accessory Power Relay. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal 1 and ground.
    • If 10 Ω or greater
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω
  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 2 and the ground circuit terminal 1.
  6. Verify the test lamp turns ON and OFF when switching the ignition between ON and OFF.
    • If the test lamp is always OFF
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K84 Keyless Entry 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 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K84 Keyless Entry Control Module.
    • If the test lamp is always ON
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K84 Keyless Entry 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 K84 Keyless Entry Control Module.
    • If the test lamp turns ON and OFF
  7. 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
  8. Ignition ON, connect a 40 A fused jumper wire between the B+ circuit terminal 5 and the ignition circuit terminal 3.
  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 Ω in the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the device.
    • If the device activates
  10. Test or replace the KR76 Retained Accessory Power Relay.
Diagnostic E:
  1. Ignition OFF and all vehicle systems OFF, disconnect the KR104A Battery Saver Relay 1 and the KR104B Battery Saver Relay 2. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuits listed below and ground.
    • KR104A Battery Saver Relay 1 – Ground circuit terminal 4
    • KR104B Battery Saver Relay 2 – Ground circuit terminal 6
    • If 10 Ω or greater
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω
  3. Ignition ON.
  4. Verify a test lamp illuminates between the B+ circuits below and ground.
    • KR104A Battery Saver Relay 1 – B+ circuit terminal 3
    • KR104B Battery Saver Relay 2 – B+ circuit terminal 3
    • If the test lamp does not illuminate

      Replace the appropriate X51A Fuse Block - Instrument Panel or the X53A Fuse Block - Rear Body

    • If the test lamp illuminates
  5. Enable battery saver mode (transport mode).
  6. Ignition OFF.
  7. Connect a test lamp between the control circuits listed below and ground
    • KR104A Battery Saver Relay 1 – Control circuit terminal 1
    • KR104B Battery Saver Relay 2 – Control circuit terminal 1
  8. Verify the test lamp momentarily flashes ON and OFF when turning the ignition ON.
    • 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 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, 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.
  9. Connect a test lamp between the control circuits listed below and ground
    • KR104A Battery Saver Relay 1 – Control circuit terminal 2
    • KR104B Battery Saver Relay 2 – Control circuit terminal 2
  10. Verify the test lamp momentarily flashes ON and OFF after turning the ignition OFF.

    11. Note: It may take up to 1 min after the ignition is switched OFF and retained accessory power is disabled before the body control module sends a command to unlatch the relay.

    • 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 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, 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
  11. Verify that a test lamp does not illuminate between the ignition circuits below and ground.
    • KR104A Battery Saver Relay 1 – Terminal 5
    • KR104B Battery Saver Relay 2 – Terminal 5
    • If the test lamp illuminates

      Repair the short to voltage on the ignition circuit

    • If the test lamp does not illuminate
  12. Ignition ON, connect a 40 A fused jumper wire between the circuits listed below.
    • KR104A Battery Saver Relay 1 – B+ circuit Terminal 3 and ignition circuit terminal 5
    • KR104B Battery Saver Relay 2 – B+ circuit Terminal 3 and ignition circuit terminal 5
  13. 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 Ω in the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the device.
    • If the device activates
  14. Test or replace the KR104A Battery Saver Relay 1 or the KR104B Battery Saver Relay 2.

Component Testing

Relay Test:
  1. Ignition OFF, disconnect the appropriate relay.
  2. Test for 70–150 Ω between terminals (85 or 1) and (86 or 2).
    • If less than 70 or greater than 150 Ω

      Replace the relay.

    • If between 70–150 Ω
  3. Test for infinite resistance between the terminals listed below:
    • (30 or 3) and (86 or 2)
    • (30 or 3) and (87 or 5)
    • (30 or 3) and (85 or 1)
    • (85 or 1) and (87 or 5)
    • (86 or 2) and (87 or 5)
    • If less than infinite resistance

      Replace the relay.

    • If infinite resistance
  4. Install a 3 A fused jumper wire between relay terminal (85 or 1) and 12 V. Install a jumper wire between relay terminal (86 or 2) and ground.
  5. Test for less than 5.0 Ω between terminals (30 or 3) and (87 or 5).
    • If 5.0 Ω or greater

      Replace the relay.

    • If less than 5.0 Ω
  6. All OK
Latching Relay Test:
  1. Ignition OFF, disconnect the appropriate KR104A Battery Saver Relay 1 or KR104B Battery Saver Relay 2.
  2. Test for 70–150 Ω between terminals 1 and 6.
    • If less than 70 or greater than 150 Ω

      Replace the relay.

    • If between 70–150 Ω
  3. Test for 70–150 Ω between terminals 2 and 6.
    • If less than 70 or greater than 150 Ω

      Replace the relay.

    • If between 70–150 Ω
  4. Test for infinite resistance between the terminals listed below:
    • 3 and 1
    • 3 and 2
    • 3 and 6
    • 5 and 1
    • 5 and 2
    • 5 and 6
    • If less than infinite resistance

      Replace the relay.

    • If infinite resistance
  5. Install a 3 A fused jumper wire between relay terminal 1 and 12 V. Install a jumper wire between relay terminal 6 and ground.
  6. Test for less than 5.0 Ω between terminals 3 and 5.
    • If 5.0 Ω or greater

      Replace the relay.

    • If less than 5.0 Ω
  7. Install a 3 A fused jumper wire between relay terminal 2 and 12 V. Install a jumper wire between relay terminal 6 and ground.
  8. Test infinite resistance between terminals 3 and 5.
    • If less than infinite resistance

      Replace the relay.

    • If infinite resistance
  9. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.