GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The PARK fuse in the fuse block - instrument panel (I/P) supplies voltage to the switch input side of the park lamp relay. The body control module (BCM) controls the park lamp relay, closing the contacts, applying voltage to the park lamp supply voltage circuit. The park lamps are illuminated any time the headlamp switch is in the park lamps ON or headlamps ON position, or anytime the BCM illuminates the headlamps.

The BCM monitors the park lamp supply voltage circuit to determine if the park lamps are receiving voltage when requested. When the BCM is commanding the headlamps ON and is not receiving voltage on the park lamps supply voltage circuit input the DTC will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2662 Park Lamp Switch Circuit Malfunction

Conditions for Running the DTC

    • The ignition switch is in the ON position.
    • The low beam or high beam headlamps are ON.

Conditions for Setting the DTC

Any of the following conditions will set this DTC:

    • The park lamp supply voltage circuit is open or shorted to ground.
    • The park lamp relay is inoperative.
    • Battery positive voltage to the park lamp relay is open.

Action Taken When the DTC Sets

DTC B2662 is stored in the BCM memory.

Conditions for Clearing the DTC

    • The BCM receives the clear code command from the scan tool.
    • A current DTC will clear when the conditions for setting the DTC are no longer present.
    • A history DTC clears after 100 malfunction free ignition cycles.

Diagnostic Aids

    • The low or high beam headlamps must be ON in order to set this DTC.
    • An open PARK fuse will set this code.
    • If the DTC is a history DTC, the problem may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the PARKLAMP SWITCH parameter in the data list.
  4. Turn the headlamp switch to the low beam headlamps ON position.
  5. Return the headlamp switch to the AUTO position.

Does the scan tool display toggle between ON and OFF?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

Are the park lamps operating properly when the headlamp switch is turned ON and then to AUTO?

Go to Step 4

Go to Step 6

4

Test the signal circuit of the headlamp switch for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 5

5

Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 9

6

Test the battery positive voltage circuit of the headlamp switch for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 7

7

Test the park lamp signal circuit of the headlamp switch for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 8

8

Inspect for poor connections at the harness connector of the headlamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 10

9

Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 11

--

10

Replace the headlamp switch. Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column.

Did you complete the replacement?

Go to Step 11

--

11

  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