GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 Canyon Pickup - 4WD 🢒 DTC 🢒 DTC B1441, B1442, or B1443
Table 1: Correct Ignition Switch Inputs

Circuit Description

The body control module (BCM) is the power mode master (PMM) responsible for sending ignition switch position information on the class 2 serial data link. The BCM monitors 3 discrete inputs from the ignition switch and the engine run flag (ERF) in order to determine the power mode. The BCM communicates this power mode information to all class 2 modules on the class 2 serial data link. The following table represents correct BCM power mode data:

Correct Ignition Switch Inputs

Ignition Switch Position

BCM input and Scan Tool Display

Ignition Accessory

Ignition 1 Run/Crank

Ignition Off/Run/Crank

OFF

Inactive

Inactive

Active

UNLOCK

Inactive

Inactive

Inactive

ACC

Active

Inactive

Inactive

ON

Active

Active

Active

START

Inactive

Active

Active

Conditions for Running the DTC

Battery positive voltage is 9.0-18.5 volts.

Conditions for Setting the DTC

The Ignition Off/Run/Crank circuit is an open, shorted to ground, or shorted to voltage.

Conditions for Clearing the DTC
    • A current DTC clears when the malfunction is no longer present for 1 second.
    • A history DTC clears when the ignition is cycled 100 times, without a repeat of the malfunction.

Step

Action

Yes

No

Schematic Reference: Body Control System Schematics

Connector End View Reference: Body Control System Connector End Views

1

Perform the Diagnostic System Check for the system exhibiting the symptom. Refer to Control Module References .

Did you perform the Diagnostic System Check?

Go to Step 2

Go to Control Module References

2
  1. Install a scan tool.
  2. Turn the ignition OFF.
  3. With the scan tool, observe the following in Body Control Module, Data Display, Inputs:
    4. • Ignition Off/Run/Crank
    • Ignition 1 Run/Crank
    • Ignition Accessory

Does the scan tool indicate that all inputs are inactive/Off?

Go to Step 3

Go to Step 6

3
  1. Turn the ignition switch to ACC.
  2. Observe the following parameters with the scan tool:
    3. • Ignition Off/Run/Crank
    • Ignition 1 Run/Crank
    • Ignition Accessory

Does the scan tool indicate that the Ignition 0 and Ignition Accessory inputs are active/On?

Go to Step 4

Go to Step 8

4
  1. Turn the ignition switch ON, with the engine OFF.
  2. Observe the following parameters with the scan tool:
    3. • Ignition Off/Run/Crank
    • Ignition 1 Run/Crank
    • Ignition Accessory

Does the scan tool indicate that the all inputs are Active/On?

Go to Step 5

Go to Step 8

5

Important: The engine may start in this step. Turn the engine OFF immediately after reviewing the input data.

  1. Turn the ignition switch to START.
  2. Observe the following parameters with the scan tool:
    3. • Ignition Off/Run/Crank
    • Ignition 1 Run/Crank
    • Ignition Accessory

Does the scan tool indicate that the Ignition Off/Run/Crank and Ignition 1 Run/Crank inputs are ON and the Ignition Accessory input is Inactive?

Go to Step 11

Go to Step 8

6
  1. Disconnect the ignition switch harness connectors.
  2. Observe the following parameters with the scan tool:
    3. • Ignition Off/Run/Crank
    • Ignition 1 Run/Crank
    • Ignition Accessory

Does the scan tool indicate that any of the Ignition Off/Run/Crank, Ignition 1 Run/Crank or Ignition Accessory inputs is Active/On?

Go to Step 7

Go to Step 9

7
  1. Disconnect the BCM harness connectors.
  2. Test the suspect ignition switch input circuits for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 11

8
  1. Disconnect the ignition switch connectors.
  2. Install a 3A fused jumper between the suspect circuits and an ignition switch B+ supply.
  3. Observe the following parameters with the scan tool:
    4. • Ignition Off/Run/Crank
    • Ignition 1 Run/Crank
    • Ignition Accessory

Does the scan tool indicate that the suspect circuits are now active/On?

Go to Step 9

Go to Step 10

9

Inspect for poor connections at the ignition switch harness connectors. 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 14

Go to Step 12

10
  1. Disconnect the BCM harness connectors.
  2. Test the suspect ignition switch input circuits for a short to ground, short to voltage, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 11

11

Inspect for poor connections at the BCM harness connectors. 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 14

Go to Step 13

12

Replace the ignition switch. Refer to Ignition and Start Switch Replacement in Steering Wheel and Column.

Did you complete the replacement?

Go to Step 14

--

13

Important: Perform the programming or setup procedure for the module if required.

Replace the BCM. Refer to Body Control Module Replacement .

Did you complete the replacement?

Go to Step 14

--

14
  1. Reconnect all components.
  2. Use the scan tool in order to clear DTCs.
  3. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does DTC B1442 or B1443 reset?

Go to Step 2

System OK