GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2005 🢒 Aztek - FWD 🢒 DTC 🢒 DTC B2665

Circuit Description

The headlamp switch provides a direct ground input into the body control module (BCM) for the headlamp switch input when the switch is activated. This input is used by the BCM in order to control the headlamps when the headlamp switch is in the HEAD position.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2665 Headlamp Switch Circuit High

Conditions for Running the DTC
    • Voltage supplied to the module is in the normal operating range, approximately 10-16 volts.
    • The headlamps must be ON.

Conditions for Setting the DTC

The BCM detects a short to ground in the headlamps signal circuit of the headlamp switch when the headlamp switch is in the HEAD position.

Action Taken When the DTC Sets

The BCM stores DTC B2665 in memory.

Conditions for Clearing the DTC
    • A current DTC B2665 clears if the BCM no longer detects a short to ground.
    • A history DTC B2665 clears after 100 consecutive ignition cycles.
    • The BCM receives the Clear Code command from the scan tool.

Diagnostic Aids
    • If the DTC B2665 is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections .
    • An intermittent short to ground in the following locations may cause an intermittent malfunction to occur:
       - The headlamps signal circuit of the headlamp switch
       - The headlamp switch
       - The BCM

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

Connector End View Reference: Master Electrical Component List

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the Park Lamp Switch parameter in the body control module (BCM) data list.

Does the scan tool display OFF?

Go to Step 3

Go to Step 4

3
  1. Activate the park lamps.
  2. With the scan tool, observe the Headlamp Switch parameter.

Does the Headlamp Switch parameter change state?

Go to Diagnostic Aids

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the headlamp switch.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Headlamp Switch parameter.

Does the scan tool display OFF?

Go to Step 7

Go to Step 5

5

Test the headlamps signal circuit of the headlamp switch for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 10

Go to Step 6

6

Inspect for a high resistance at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 10

Go to Step 8

7

Inspect for a high resistance at the harness connector of the headlamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 10

Go to Step 9

8

Replace the BCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 10

--

9

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the replacement?

Go to Step 10

--

10
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK