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.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Battery Voltage

1

1

--

--

Ignition 1 Voltage

1

1

--

--

Signal

1

1

2

--

Line Hot

1

1

1

--

Line Neutral

1

1

1

--

Ground

--

1

--

--

1. accessory AC/DC power control module always OFF

2. accessory AC/DC power control module always ON

Circuit/System Description

The accessory AC/DC power control module converts 12 volt direct current (DC) battery voltage to 110-120 volt alternating current (AC) in order to operate AC powered devices. The accessory AC/DC power control module provides up to 150 watts of power. The accessory AC/DC power control module is connected to a chassis ground circuit and receives fuse protected battery voltage.

The accessory power outlet has an internal switch, that detects when an AC powered device is plugged into the outlet. When the ignition is ON and a 120 volt AC powered device is plugged into the accessory power outlet, the normally-open switch in the accessory power outlet, closes. When the accessory AC/DC power control module detects the voltage from the accessory power outlet switch, the inverter module begins to supply 110-120 volts AC to the accessory power outlet after a 1.5 second delay.

Diagnostic Aids

A household 120 volt duplex receptacle outlet tester should not be used to diagnose this system. The tester will indicate an open ground, which is a normal condition.

Reference Information

Schematic Reference

Cigar Lighter/Power Outlet Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Power Outlets Description and Operation

Electrical Information Reference

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

Circuit/System Verification

  1. Ignition ON, connect an AC power extension cord to the accessory power outlet. Inserting the extension cord plug into the accessory power outlet turns the accessory AC/DC power control module ON.
  2. Test for 110-120 volts AC across the line hot and line neutral terminals of the extension cord.
  3. Test for 59-61 Hz AC across the line hot and line neutral terminals of the extension cord.
  4. If not within the specified value, replace the accessory AC/DC power control module.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connectors at the accessory AC/DC power control module.
  2. Ignition OFF and the scan tool disconnected, open and close the driver door and wait 1 minute. Test for less than 5 ohms between the ground circuit terminal 1 X2 and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 2 X2 and ground.
  5. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  6. Test for less than 1.0 volt between the accessory AC/DC power control module circuit terminal listed below and ground:
  7. • The accessory AC/DC power control module terminal 2 X1.
    • The accessory AC/DC power control module terminal 4 X1.
    • The accessory AC/DC power control module terminal 6 X1.
    If greater than the specified value, test the appropriate circuit for a short to voltage. If the circuit tests normal, test or replace the accessory power outlet.
  8. Test for infinite resistance between the accessory AC/DC power control module circuit terminal listed below and ground:
  9. • The accessory AC/DC power control module terminal 4 X1.
    • The accessory AC/DC power control module terminal 6 X1.
    If less than the specified value, test the appropriate circuit for a short to ground.
  10. Ignition OFF, test for less than 5 ohms between the accessory power outlet line circuit terminal and the accessory AC/DC power control module terminal listed below:
  11. • The line hot circuit terminal 3 and the accessory AC/DC power control module terminal 4 X1.
    • The line neutral circuit terminal 6 and the accessory AC/DC power control module terminal 2 X1.
    If greater than the specified range, test the appropriate line circuit for an open/high resistance. If the circuit tests normal, test or replace the accessory power outlet.
  12. Disconnect the harness connector at the accessory power outlet.
  13. Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal 4 and ground.
  14. If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance.
  15. Connect the harness connector at the accessory power outlet, and connect an AC powered device to the accessory power outlet.
  16. Ignition ON, verify that a test lamp illuminates between the accessory AC/DC power control module signal circuit terminal 2 X1 and ground.
  17. If the test lamp does not illuminate, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the accessory power outlet.
  18. If all circuits test normal, replace the accessory AC/DC power control module.

Component Testing

Accessory Power Outlet

  1. Ignition OFF, remove the accessory power outlet.
  2. Test for greater than 1M ohm between terminal 6 and terminal 3.
  3. If less than the specified range, replace the accessory power outlet.
  4. Test for less than 3 ohms between the following terminals:
  5. • The terminal 6 and the accessory hot terminal
    • The terminal 3 and the accessory neutral terminal
    If greater than the specified range, replace the accessory power outlet.
  6. Test for infinite resistance between terminal 4 and terminal 1.
  7. If not the specified value, replace the accessory power outlet.
  8. Connect an AC powered device to the accessory power outlet.
  9. Test for less than 3 ohms between terminal 4 and terminal 1.
  10. If greater than the specified range, replace the accessory power outlet.
  11. Test for 2.9-3.1 volts, with the DMM set on the diode setting and the positive test lead to terminal 6 and the negative test lead to terminal 3.
  12. If not within the specified range, replace the accessory power outlet.
  13. Test for 0.0-0.1 volts, with the DMM set on the diode setting and the positive test lead to terminal 3 and the negative test lead to terminal 6.
  14. If greater than the specified range, replace the accessory power outlet.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Accessory Power Receptacle Replacement
    •  Control Module References for control module replacement, setup, and programming