GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The body control module (BCM) uses a key in ignition input in order to control certain features in the vehicle. These features are in the following systems:

    • Content Theft Deterrent, if equipped
    • Audible Warnings
    • Automatic Door Locks

The BCM detects a key in the ignition when the signal circuit is low.

Conditions for Running the DTC

The ignition is on.

Conditions for Setting the DTC

    • The ignition 0 input is active (high signal) and the key in ignition input is inactive (high signal).
    • The conditions above must be present for more than 0.3 seconds.

Action Taken When the DTC Sets

The BCM stores DTC B2964 in memory.

Conditions for Clearing the DTC

    • The DTC becomes history when the fault is no longer present.
    • A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
    • You may use a scan tool in order to clear the DTC.

Step

Action

Value(s)

Yes

No

Schematic Reference: Diagnostic System Check - Audible Warnings

1

Did you perform the Audible Warnings Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With the scan tool, observe the Key In Ignition parameter in the Body Control Module input data list.

Does the Key In Ignition parameter display Yes?

--

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

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the BCM connector C2.
  3. Connect a test lamp between the key in ignition input circuit and battery positive voltage.
  4. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

--

Go to Step 7

Go to Step 4

4

Test the key in ignition input circuit for an open or a high resistance. 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 ground circuit of the ignition key alarm switch for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 6

6

Inspect for poor connections at the harness connector of the ignition 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 10

Go to Step 8

7

Inspect for poor connections at the harness connector of the 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 10

Go to Step 9

8

Replace the ignition switch. Refer to Ignition Switch Replacement - On Vehicle in Steering Wheel and Column.

Did you complete the replacement?

--

Go to Step 10

--

9

Important: Perform the set up procedure for the replacement BCM.

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

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