B3600

DTC B3600

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B3600 03
- Voltage Below Threshold

DTC B3600 07
- Voltage Above Threshold

Diagnostic Fault Information






Circuit/System Description

Voltage for the interior backlighting components is supplied from the body control module (BCM). The BCM applies a voltage reference through the 12-volt reference circuit to the headlamp and panel dimmer switch. When the dimming switch is placed in the desired position, the dimmed voltage setting is applied from the headlamp and panel dimmer switch through the instrument panel (I/P) lamp dimmer switch signal circuit to the BCM. The BCM then applies the dimmed voltage to the lamp supply voltage circuits and they are dimmed to the correct level.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

B3600 03

The BCM detects a voltage that is lower than 0.10 volt on the I/P lamp dimmer switch signal circuit.

B3600 07

The BCM detects a voltage that is higher than 4.97 volts on the I/P lamp dimmer switch signal circuit.

Action Taken When the DTC Sets

The I/P lamps are not illuminated.

Conditions for Clearing the DTC

The BCM clears this code from current when the fault is removed from the system.

Circuit/System Verification

Ignition ON, headlamp switch to HEAD, vary the interior lamp dimming switch from dim to full bright. The I/P lamps should dim and then become full bright.

Circuit/System Testing

1. Ignition ON and clear the DTC. Use the scan tool Incandescent Dimming output control to adjust the dimming level of the I/P lamps from low to high.

• If the lamps cannot be controlled with the scan tool, replace the BCM.

2. Monitor the Dimming Control Signal voltage parameter in the scan tool BCM data list while adjusting the dimmer switch from high to low.
3. If the voltage is above 4.97 volts, test for a short to voltage in the I/P lamp dimmer switch signal circuit.

• If the circuit/connections test normal, replace the headlamp and panel dimmer switch.

4. If the voltage drops below 0.10 volt, test for a short to ground, open, or high resistance in the I/P lamp dimmer switch signal circuit.

• If the circuit/connections test normal, replace the headlamp and panel dimmer switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Headlamp Switch Replacement (with RPO SLT) Headlamp Switch Replacement (without RPO SLT)
* Control Module References for BCM replacement, setup, and programming Programming and Relearning