Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions has overviews of all diagnostic categories.

DTC Descriptor

DTC B3588 00

Rear Fog Lamp Switch Circuit Malfunction

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Rear Fog Lamp Switch Signal	-	-	-	B3588 00

Circuit/System Description

The rear fog lamp switch signal circuit is grounded momentarily by pressing the rear fog lamp switch. The body control module (BCM) energizes the rear fog lamp supply voltage circuit which illuminates the rear fog lamp.

Conditions for Running the DTC

•	The ignition is turned ON.

•	Rear fog lamp switch activated.

Conditions for Setting the DTC

Rear fog lamp switch stuck.

Action Taken When the DTC Sets

Rear fog lamp inoperative.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

Reference Information

Schematic Reference

Fog Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

Control Module References for information on diagnostic tools

Circuit/System Verification

Ignition ON, observe the diagnostic tool's parameter Rear Fog Lamp Switch. The reading should change between Active/Inactive when changing between pressed and released rear fog lamp switch button.

Circuit/System Testing

1.	Ignition OFF, disconnect the X1 and X3 harness connector at the K9 Body Control Module.

2.	Test for less than 0.3 V at the K9 Body Control Module signal circuit harness terminal 9 X1 and ground.

3.	If greater than the specified value, test the signal circuit for an short to voltage

4.	Test for less than 0.3 V at the K9 Body Control Module 12 V reference circuit harness terminal 4 X3 and ground.

5.	If greater than the specified value, test the 12 V reference circuit for a short to voltage.

6.	Test for infinite resistance between the K9 Body Control Module signal circuit harness terminal 9 X1 and ground.

7.	If lower than the specified value, test the signal circuit for a short to ground.

8.	Test for infinite resistance between the K9 Body Control Module 12 V reference circuit harness terminal 4 X3 and ground.

9.	If lower than the specified value, test the 12 V reference circuit for a short to ground.

10.	Press and hold the rear fog lamp switch button.

11.	Test for 2.0-2.4 kΩ between the K9 Body Control Module 12 V reference circuit harness terminal 4 X3 and the K9 Body Control Module signal circuit harness terminal 9 X1.

12.	If all circuits test normal, replace the K9 Body Control Module.

Component Testing

Static Test

Ignition OFF, disconnect the harness connector at the S30 Headlamp Switch. Press and hold the rear fog lamp switch button, test for 2.0-2.4 Ω at the S30 Headlamp Switch terminal 1 and terminal 12.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Headlamp Switch Replacement

•	Control Module References for information on BCM replacement, setup, and programming