GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B1370 01: Device Ignition 1 Circuit Short to Battery

DTC B1370 04: Device Ignition 1 Circuit Open Circuit

DTC B1380 01: Device Ignition ACCESSORY Circuit Short to Battery

DTC B1380 04: Device Ignition ACCESSORY Circuit Open Circuit

DTC B1441 01: Device Ignition OFF, RUN and CRANK Circuit Short to Battery

DTC B1441 06: Device Ignition OFF, RUN and CRANK Circuit Short to Ground or Open

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Device Ignition 1 Circuit

B1370 04

B1370 04

B1370 01

--

Device Ignition ACCESSORY Circuit

B1380 04

B1380 04

B1380 01

--

Device Ignition OFF, RUN and CRANK Circuit

B1441 06

B1441 06

B1441 01

--

Conditions for Running the DTC

B1370 01

Ignition switch is in the OFF or ACC positions.

B1370 04

Ignition switch is in the START position.

B1380 01, B1380 04, B1441 01, B1441 06

The system voltage is 9-18 volts.

Conditions for Setting the DTC

B1370 01, B1380 01, B1441 01

BCM detects a short to voltage.

B1370 04, B1380 04

The BCM detects an open.

B1441 06

The BCM detects an open or short to ground.

Conditions for Clearing the DTC

    • A current DTC clears when the malfunction is no longer present.
    • A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Reference Information

Schematic Reference

    •  Power Distribution Schematics
    •  Body Control System Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Power Mode Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

With a scan tool, access Body Control Module, Power Mode data display list and compare all parameters listed with the corresponding ignition key position. The PMM Power Mode Parameters table below illustrates the correct state of these input parameters (circuits) in correspondence to the ignition switch position. The circuits which the individual parameters are related to are in parentheses.

PMM Power Mode Parameters

Ignition Switch Position

Current Power Mode

Run Relay Command (Off/Run Crank Voltage Circuit)

Ignition Switch Accessory Signal (Accessory Voltage Circuit)

Run/Crank Relay Command (Ignition 1 Voltage Circuit

Off Key Out

Off

Off

Inactive

OFF

Off Key IN

Off

Off

Inactive

OFF

Accessory

Accessory

Off

Active

OFF

Run

Run

ON

Active

ON

Start

Crank Request

OFF

Inactive

ON

If any parameters are incorrect in any key position, refer to the Circuit/System Testing or Component Testing.

Circuit/System Testing

    Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

  1. Inspect the Ignition Switch B+ fuse for an open.
  2. If the fuse is open, test the circuits listed below for a short to ground:
    • Ignition switch B+
    • Accessory voltage
    • Off/Run crank voltage
    • Ignition 1 voltage
    If all circuits test normal, replace the BCM.
  3. Ignition OFF, disconnect the harness connector at the ignition switch.
  4. Ignition ON, verify that a test lamp illuminates between the ignition switch B+ circuit terminal 2 and ground.
  5. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.

    Important: The ignition switch component test must be preformed before proceeding with this test to verify the integrity of the switch.

  6. Ignition OFF, disconnect X2 and X4 harness connectors at the BCM.
  7. Ignition key out, test for less than 1-volt between the circuit terminals listed below and ground:
  8. • Accessory voltage terminal C8
    • Ignition 1 voltage terminal D3
    • Off/Run/Crank voltage terminal 56
    If greater than the specified range, test the circuit for a short to voltage.
  9. Test for less than 1 ohm between the BCM terminals and the ignition switch terminals listed below:
  10. • Accessory voltage terminal C8 and 4
    • Ignition 1 voltage terminal D3 and 3
    • Off/Run/Crank voltage terminal 56 and 5
    If greater than the specified range, test the circuit for an open/high resistance.
  11. If all circuits test normal, replace the BCM.

Component Testing

Ignition Switch

Using the Resistance Test below, check the resistance between the pins of the ignition switch listed in each switch position listed.

If any reading is other than specified, replace the ignition switch.

Resistance Test

Ignition Switch Position

Terminals 2 and 3

Terminals 2 and 5

Terminals 2 and 6

Terminals 5 and 6

Off Key Out

Infinite

Infinite

Infinite

Infinite

Off Key IN

Infinite

< 5.0 ohms

Infinite

Infinite

Accessory

< 5.0 ohms

Infinite

Infinite

Infinite

Run

< 5.0 ohms

Infinite

Infinite

< 5.0 ohms

Start

Infinite

Infinite

Infinite

1275-1325 ohms

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Ignition and Start Switch Replacement
    •  Control Module References for BCM replacement, setup, and programming