B3600
DTC B3600
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC B3600 03
- Passenger Compartment Dimming Request Signal Circuit Low Voltage
DTC B3600 07
- Passenger Compartment Dimming Request Signal Circuit High Voltage
Diagnostic Fault Information
Circuit/System Description
The instrument panel dimmer switch is used to increase and decrease the brightness of the interior backlighting components. The body control module (BCM) supplies a 12 V reference to the backlight dimmer switch, which is part of the headlamp switch. When the backlight dimmer switch is placed in a desired brightness position, reference voltage is applied through the dimmer switch rheostat to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage to the LED dimming control circuit to all related interior lamps, illuminating them to the desired level of brightness.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
* The BCM detects a short to ground or open in the 12 V reference circuit.
* The BCM detects a short to ground or open in the instrument panel dimming signal circuit.
Action Taken When the DTC Sets
The Instrument Panel lamps are not illuminated.
Conditions for Clearing the DTC
A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.
Reference Information
Schematic Reference
Interior Lights Dimming Schematics (Interior Lights Dimming Schematics)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
Interior Lighting Systems Description and Operation (Interior Lighting Systems)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
Ignition ON, cover the ambient light sensor, vary the interior lamp dimming switch from dim to full bright. The instrument panel lamps should dim and then become full bright.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the S30 Headlamp Switch.
2. Ignition ON, test for 11.8-12.2 V between the 12 V reference circuit terminal 1 and ground.
• If greater than the specified range, test the 12 V reference circuit for short to voltage. If the circuit tests normal, replace the K9 Body Control Module.
• If less than the specified range, test the 12 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.
3. Verify the scan tool Incandescent Dimming parameter is less than 10%.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module.
4. Install a 3 A fused jumper wire between the signal circuit terminal 12 and the 12 V reference circuit terminal 1. Verify the scan tool Incandescent Dimming parameter is greater than 90%.
• If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.
5. If all circuits test normal, test or replace the S30 Headlamp Switch.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Headlamp Switch Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming