GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2005 🢒 Bonneville 🢒 Restraints 🢒 SIR 🢒 DTC B2657

Circuit Description

The HVAC control module provides a switched ground to the key cylinder halo light. The halo light is supplied voltage at all times. The HVAC control module samples the voltage on the circuit from the halo light to determine the state of the input.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2657 Ignition Halo Lamp Output Circuit Malfunction

Conditions for Running the DTC
    • The HVAC control module is powered.
    • DTC B1327 is not current.

Conditions for Setting the DTC

The DTC sets if the HVAC control module senses no voltage on the circuit from the halo light for a period longer than 2 seconds.

Action Taken When the DTC Sets

The HVAC control module disables the internal switch that controls the halo light.

Conditions for Clearing the DTC

The DTC will be cleared from the HVAC control module when it receives a new power mode signal over the class 2 communications system. If the HVAC control module senses no voltage on the halo light circuit the DTC will reset after 2 seconds.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Observe the key cylinder halo operation. Command both the ON and OFF states. Repeat the commands as necessary.

Step

Action

Yes

No

Schematic Reference: Interior Lights Schematics

Connector End View Reference: Master Electrical Component List in Wiring Systems

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, command the Key Light (Halo) ON and OFF from the climate control panel (CCP) Miscellaneous Test data list.

Does the ignition key cylinder lamp turn ON and OFF with each command?

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

Go to Step 3

3
  1. Turn OFF the ignition.
  2. Remove the ignition key cylinder lamp bulb.
  3. Connect a test lamp between the ignition key cylinder lamp battery positive voltage circuit and the key cylinder lamp control circuit.
  4. Turn ON the ignition, with the engine OFF.
  5. With a scan tool, command the Key Light (Halo) ON and OFF.

Does the test lamp turn ON and OFF with each command?

Go to Step 6

Go to Step 4

4

Test the ignition key cylinder lamp battery positive voltage circuit for high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 5

5

Test the ignition key cylinder lamp control circuit for a high resistance or open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 7

6

Inspect for poor connections at the ignition key cylinder lamp bulb. 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 10

Go to Step 8

7

Inspect for poor connections at the harness connector of the HVAC control module. 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 10

Go to Step 9

8

Replace the ignition key cylinder lamp bulb. Refer to Ignition Lock Cylinder Bulb Replacement .

Did you complete the replacement?

Go to Step 10

--

9

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

Did you complete the replacement?

Go to Step 10

--

10

Operate the system in order to verify the repair.

Did you find and correct the condition?

System OK

Go to Step 2