Ignition Mode Switch Indicator Malfunction
Ignition Mode Switch Indicator Malfunction
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 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 Body Control Module (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 provide 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
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. 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
2. All OK.
Circuit/System Testing
1. Ignition OFF and all vehicle 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 connections.
• If less than 10 ohms
3. Test for less than 1 V between each of the control circuits listed below and ground:
* Control circuit terminal 5
* Control circuit terminal 2
• 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 control 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 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 less than 1 V
4. Ignition OFF, connect the harness connector at the S38 Ignition Mode Switch.
5. Ignition ON, disconnect the harness connector at the S38 Ignition Mode Switch.
6. Test for greater than 3 V between the control circuit terminal 5 and ground.
• If 3 V or less
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 3 V or greater
7. Connect the harness connector at the S38 Ignition Mode Switch.
8. Ignition ACCESSORY, disconnect the harness connector at the S38 Ignition Mode Switch.
9. Test for greater than 3 V between the control circuit terminal 2 and ground.
• If 3 V or less
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 3 V or greater
10. Test or replace the S38 Ignition Mode Switch.
Component Testing
1. Ignition OFF, disconnect the harness at the S38 Ignition Mode Switch.
2. Connect a jumper wire between the S38 Ignition Mode Switch terminal 4 and ground.
3. Connect a 3 A fused jumper wire between the S38 Ignition Mode Switch terminal 5 and B+.
4. Verify the green LED illuminates.
• If the LED does not illuminate
Replace the S38 Ignition Mode Switch.
• If the LED illuminates
5. Connect a 3 A fused jumper wire between the S38 Ignition Mode Switch terminal 2 and B+.
6. Verify the amber LED illuminates.
• If the LED does not illuminate
Replace the S38 Ignition Mode Switch.
• If the LED illuminates
7. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Ignition and Start Switch Replacement Ignition and Start Switch Replacement
* Control Module References Control Module References for the Body Control Module replacement, programming and setup