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 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 or front fog lamps illuminated.

• | Rear fog lamp switch activated.

### Conditions for Setting the DTC

Rear Fog Lamp switch stuck.

### 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 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 theK9 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 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