For 1990-2009 cars

### Diagnostic Instructions

1. Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
2. Review Strategy Based Diagnosis for an overview of the diagnostic approach.
3. Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### 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 | -- | -- | -- | B3588 00

### Circuit/System Description

The rear fog lamp switch signal circuit is grounded through a resistor 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.

• | Low beam is illuminated.

• | Rear fog lamp switch activated.

### Conditions for Setting the DTC

Rear Fog Lamp switch stuck.

### Action Taken When the DTC Sets

The rear fog lamp is 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 scan tool information

### Circuit/System Verification

Ignition ON, observe the scan tool Rear Fog Lamp Switch parameter. 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 (BCM).
2. Ignition ON, test for less than 0.3 V at the K9 Body Control Module (BCM) signal circuit harness connector X1 terminal 9 and ground.

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

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

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

4. Ignition OFF, test for infinite resistance between the K9 Body Control Module (BCM) signal circuit harness connector X1 terminal 9 and ground.

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

5. Test for infinite resistance between the K9 Body Control Module (BCM) 12 V reference circuit harness connector X3 terminal 4 and ground.

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

6. Press and hold the front fog lamp switch button.
7. Test for 100-200 Ω between the K9 Body Control Module (BCM) 12 V reference circuit harness connector X3 terminal 4 and the K9 Body Control Module (BCM) signal circuit harness connector X1 terminal 9.

⇒ | If not within the specified range, test the 12 V reference circuit and the signal circuit for an open/high resistance. If the circuits test normal replace the S30 Headlamp Switch

8. If all circuits test normal, replace the K9 Body Control Module (BCM).

### 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 100-200 Ω at the S30 Headlamp Switch terminal 1 and terminal 12.

⇒ | If not within the specified range replace the S30 Headlamp Switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Headlamp Switch Replacement

• | Control Module References for BCM replacement, setup and programming