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Vehicle Will Not Change Power Mode




Vehicle Will Not Change Power Mode

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.

Diagnostic Fault Information






Circuit/System Description

The Ignition Mode Switch has two LED's that indicate the vehicle power mode. When the vehicle is in the off mode, both LED's will be off. Pressing the Ignition Mode Switch button once (without the brake pedal applied), the vehicle enters the accessory mode and the amber LED (ACC) will illuminate. The accessory mode has a 5 minute timeout to reduce battery drain. Pressing the Ignition Mode Switch button a second time (without the brake pedal applied), the vehicle enters the run/start mode (without the engine running) and the green LED (Run/Start) will illuminate. Pressing and holding the push button start switch for at least 5 seconds will place the vehicle in run/start mode (without the vehicle running) and the green LED (Run/Start) will illuminate. With the ignition off (with the brake pedal applied), pressing the Ignition Mode Switch button once, the vehicle will enter run/start mode and the green LED (run/start) will illuminate. This will start the engine. Both LED's have the voltage supplied from the BCM. The Ignition Mode Switch sends the Ignition Mode Switch status to the Keyless Entry Control Module and to the BCM. The Keyless Entry Control Module sends a redundant signal to the BCM with the Ignition Mode Switch status.

The Ignition Mode Switch contains two individual switches that provides redundant switch inputs to both the BCM and the Keyless Entry Control Module. The BCM supplies the Ignition Mode Switch a constant B+ signal. The BCM monitors this signal to determine if the switch is released or pressed. When the Ignition Mode Switch is not pressed, voltage on the signal circuit is pulled down through two resistors in the switch. When the Ignition Mode Switch is pressed, voltage on the signal circuit is pulled down through only one resistor, changing the voltage seen at the BCM and indicating that the Ignition Mode Switch is pressed.

The Keyless Entry Control Module monitors voltage on the switch is the same manner as the BCM, but monitors the second switch located in the Ignition Mode Switch.

Reference Information

Schematic Reference

Power Distribution Schematics Power Distribution 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. Verify DTC B097B 08 or B097B 61 is not set.

• If either DTC is set
Test or replace the S38 Ignition Mode Switch.

• If the DTCs are not set

2. Verify the green LED illuminates when the S38 Ignition Mode Switch is pressed and held for at least 5 seconds, with the brake pedal released.

• If the green LED does not illuminate
Refer to Circuit/System Testing.

• If the green LED illuminates

3. All OK.

Circuit/System Testing

1. Ignition OFF and all systems OFF, disconnect the harness connector at the S38 Ignition Mode Switch. 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 4 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. Test for less than 10 ohms between the low reference circuit terminal 7 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, replace the K84 Keyless Entry Control Module.

• If less than 10 ohms

4. Connect the S38 Ignition Mode Switch, ignition ON.

5. Disconnect the S38 Ignition Mode Switch.

6. Verify the scan tool Body Control Module Push Button Ignition Switch Voltage parameter is greater than 11 V.

• If 11 V or less

1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module.

2. Test for infinite resistance between the signal circuit terminal 6 and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance, replace the K9 Body Control Module.

• If greater than 11 V

7. Install a 3 A fused jumper wire between the signal circuit terminal 6 and ground.

8. Verify the scan tool Body Control Module Push Button Ignition Switch Voltage parameter is less than 1 V.

• If 1 V or greater

1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module, ignition ON.

2. Test for less than 1 V between the signal circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.

• If less than 1 V

3. Test for less than 2 ohms in 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 K9 Body Control Module.

• If less than 1 V

9. Connect the harness connector at the S38 Ignition Mode Switch.

10. Verify the scan tool Body Control Module Push Button Ignition Switch Voltage parameter is 8-10 V, with the S38 Ignition Mode Switch released.

• If not between 8-10 V
Test or replace the S38 Ignition Mode Switch.

• If between 8-10 V

11. Verify the scan tool Body Control Module Push Button Ignition Switch Voltage parameter is 4-7 V, with the S38 Ignition Mode Switch pressed.

• If not between 4-7 V
Test or replace the S38 Ignition Mode Switch.

• If between 4-7 V

12. Disconnect the X1 harness connector at the K84 Keyless Entry Control Module.

13. Test for infinite resistance between the signal circuit terminal 11 and ground.

• If less than infinite resistance
Repair the short to ground on the circuit.

• If infinite resistance

14. Ignition ON.

15. Test for less than 1 V between the signal circuit terminal 11 and ground.

• If 1 V or greater
Repair the short to voltage on the circuit.

• If less than 1 V

16. Test for 4.5-5.5k ohms between the signal circuit terminal 11 and the low reference circuit terminal 12, with the S38 Ignition Mode Switch released.

• If not between 4.5-5.5k ohms

1. Ignition OFF.

2. Test the signal circuit for an open/high resistance.

• If open/high resistance, repair the open/high resistance in the circuit.

• If not an open/high resistance, test or replace the S38 Ignition Mode Switch.

• If between 4.5-5.5k ohms

17. Test for 1-1.5k ohms between the signal circuit terminal 11 and the low reference circuit terminal 12, with the S38 Ignition Mode Switch pressed.

• If not between 1-1.5k ohms
Test or replace the S38 Ignition Mode Switch.

• If between 1-1.5k ohms

18. Replace the K84 Keyless Entry Control Module.

Component Testing

1. Ignition OFF, disconnect the harness connector at the S38 Ignition Mode Switch.

2. With the S38 Ignition Mode Switch released, test for 4.5-5.5k ohms between the terminals listed below:

* Signal terminal 6 and ground terminal 4

* Signal terminal 3 and low reference terminal 7

• If not between 4.5-5.5k ohms
Replace the Ignition Mode Switch.

• If between 4.5-5.5k ohms

3. With the S38 Ignition Mode Switch pressed, test for 1-1.5k ohms between the terminals listed below:

* Signal terminal 6 and ground terminal 4

* Signal terminal 3 and low reference terminal 7

• If not between 1-1.5k ohms
Replace the Ignition Mode Switch.

• If between 1-1.5k ohms

4. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

* Ignition and Start Switch Replacement Service and Repair

* Control Module References Control Module References for Body Control Module or Keyless Entry Control Module replacement, programming and setup

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