GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • 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

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

I/P Dimming Voltage Reference

B1395 03, B3600 03

B1395 03, B2652 00, B3600 03

B1395 07

--

Courtesy Lamp Voltage Reference

B2615 00, B2615 02

B2615 00, B2615 04

B2615 00, B2615 01

--

LED Dimming Voltage Reference

B2610 00, B2610 02

B2610 00, B2610 04

B2610 00, B2610 01

--

LED Indicator Dimming Volage Reference

B2625 00

B2625 00

B2625 00

--

Dome Lamp Switch Signal

2

2

2

--

Left Front Door Open Switch Signal

3

3

3

--

Left Rear Door Open Switch Signal

4

4

4

--

Right Front Door Open Switch Signal

3

3

3

--

Right Rear Door Open Switch Signal

4

4

4

--

Stop Lamp Switch Signal

B1395 03, B3600 03

--

--

--

Dome/Reading Lamp Control

B2615 00

B2615 00

--

--

Dome/Reading Lamp Supply Voltage

1

1

--

--

Exterior Lamps Illumination Supply Voltage

5

5

5

--

Inadvertent Power Control

5

5

5

--

I/P Lamps Dimming Control

B2652 00

B2652 00

B2652 00

--

Dome/Reading Lamp Low Control - Driver Door

--

1

--

--

Dome/Reading Lamp Low Control - Passenger Door

--

1

--

--

Exterior Lamps Low Reference

--

5

--

--

I/P Dimmer Switch Ground

--

2

--

--

LH Vanity Mirror Courtesy Lamp Ground

--

1

--

--

Overhead Console Courtesy Lamp Ground

--

1

--

--

Rear Dome Lamp Ground

--

1

--

--

RH Vanity Mirror Courtesy Lamp Ground

--

1

--

--

1. Courtesy Lamps Malfunction

2. Dome Lamp Switch Malfunction

3. Door Open Switch Malfunction - Front

4. Door Open Switch Malfunction - Rear

5. Exterior Lamps Malfunction

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.

Reference Information

Schematic Reference

Interior Lights Dimming Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior 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, 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 OFF, disconnect the harness connector at the headlamp switch.
  2. Ignition OFF, verify that a test lamp illuminates between the ground circuit terminal 8 and B+.
  3. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify the scan tool Dimming Control Signal parameter is less than 0.1 volts.
  5. If greater than the specified range, test the signal circuit terminal 13 for a short to voltage. If the circuit tests normal, replace the BCM.
  6. Ignition ON, test for 12 volts between the I/P dimming voltage reference circuit terminal 15 and ground.
  7. If less than the specified value, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  8. Install a 3A fused jumper wire between the signal circuit terminal 13 and the voltage reference circuit terminal 15. Verify the scan tool BCM Dimming Control Signal parameter is greater than 2.6 volts.
  9. If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  10. If all circuits test normal, test or replace the 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