B3600

DTC B3600

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Strategy Based Diagnosis
* Diagnostic Procedure Instructions

DTC Descriptor
DTC B3600 03
- Voltage Below Threshold

Diagnostic Fault Information






Circuit/System Description

Voltage for the interior backlighting components is supplied from the Panel Dimming Fuse in the rear electrical center to the body control module (BCM). The BCM applies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp dimming switch, which is part of the headlamp switch. When the dimming switch is placed in the desired position, the dimmed voltage setting is applied from the interior lamp dimming switch through the I/P dimming control circuit to the BCM. The BCM then applies the dimmed voltage to the I/P lamps supply voltage circuit and they dim to the correct level. The I/P lamps are located in the following components:

* Cigar lighter
* Door lock switches
* Headlamp switch
* Hazard switch
* I/P cluster
* Lumbar switches
* Power window switch
* Power mirror switches
* Power seats switches
* PRNDL
* Sunroof switch
* Sunshade switch
* TCS switch
* Universal garage door opener switch

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

B3600 03

The BCM detects a voltage that is lower then 5 volts on the I/P dimming control 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, cover the ambient light sensor, 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. Clear the DTC. Disconnect the headlamp switch.
2. Connect a DMM between the I/P dimming voltage reference circuit and the negative terminal of the battery.
3. Ignition ON, test for 9-14 volts.

• If less than 9 volts, test the I/P dimming voltage reference circuit for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the BCM.
• If greater than 14 volts, test the I/P dimming voltage reference circuit for a short to voltage. If the circuit/connections test normal, replace the BCM.

4. Disconnect the DMM. Install a jumper between I/P dimming voltage reference circuit and the I/P dimming control circuit.
5. Verify that DTC B3600 03 does not set.

• If the DTC resets, then test for a short to ground in the I/P dimming control circuit. If the circuit/connections test normal, replace the BCM.

6. If all circuits/connections test normal, replace the headlamp switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

* Headlamp Switch Replacement
* Programming and Relearning for BCM setup, and programming. Programming and Relearning