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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1689 (Wiring Systems And Power Management - DTC B1370 To DTC B1433) >> DTC B1370-B1379, B1380-B1389, or B1440-B1443 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
  1. Inspect for an open B+ fuse to the ignition switch. The fuse should be OK.
    • If the fuse is open, test the following circuits for a short to ground, if all circuits test OK, replace the BCM.
      • B+ - terminal 3
      • Ignition - terminal 1
      • Ignition - terminal 2
      • Ignition - terminal 5
      • Ignition voltage - BCM terminal 21, X1
      • Accessory wakeup serial data - BCM terminal 19, X1
  2. Disconnect the harness connector at the ignition switch.
  3. Verify that a test lamp illuminates between the B+ circuit terminal 3 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
    4. NOTE: The ignition switch component test must be performed before proceeding with this test to verify the integrity of the switch.
  4. Perform the ignition switch component test. The test should pass.
    • If the ignition switch fails, replace the ignition switch.
  5. Ignition OFF, disconnect the X1 harness connector at the BCM, test for less than 1.0 V between the following circuit terminals of the BCM and ground.
    • Off/Run/Crank voltage terminal 2
    • Ignition key resistor signal terminal 4
    • Ignition 1 voltage terminal 14
    • Accessory voltage terminal 21
    • If greater than specified, test the circuit for a short to voltage.
  6. Test for less than 1.0 Ω of resistance between the BCM and the ignition switch on the following circuit terminals.
    • Ignition key resistor signal, BCM terminal 4 and ignition switch terminal 4
    • Off/Run/Crank voltage, BCM terminal 2 and ignition switch terminal 5
    • Accessory voltage, BCM terminal 21 and ignition switch terminal 2
    • Ignition 1 voltage, BCM terminal 14 and ignition switch terminal 1
    • If greater than specified, repair the circuit for open/high resistance
  7. Test for infinite resistance between the ignition key resistor signal circuit terminal 4 of the BCM and ground.
    • If less than specified, repair the signal circuit for a short to ground.
  8. If all circuits test normal, replace the BCM.
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