## Multiplex Control System

#### Multiplex Control Unit Input Test (cont'd)

22-278

4. With the connectors still disconnected, make these input tests at the connector.

- If any test indicates a problem, find and correct the cause, then recheck the system.
- If all the input tests prove OK, go to step 5.

Cavity | Wire | Test condition | Test: Desired result | Possible cause if result is not obtained
J4 | BLK | Under all conditions | Check for continuity to ground: There should be continuity. |

- Poor ground (G301)
- An open in the wire

Y6 | BLK | Under all conditions | Check for continuity to ground: There should be continuity. |

- Poor ground (G501)
- An open in the wire

Y1 | BLK | Under all conditions | Check for continuity to ground: There should be continuity. |

- Poor ground (G502)
- An open in the wire

J2 | WHT/RED | Under all conditions | Check for voltage to ground: There should be battery voltage. |

- Blown No. 9 (10A) fuse in the under-hood fuse/relay box
- An open in the wire

5. Reconnect the connectors to the under - dash fuse/relay box and make sure these input tests at the appropriate connectors on the under - dash fuse/relay box.

- If any test indicates a problem, find and correct the cause, then recheck the system.
- If all the input tests prove OK, the multiplex control unit must be faulty, replace the under - dash fuse/relay box assembly.

Cavity | Wire | Test condition | Test: Desired result | Possible cause if result is not obtained
Q3 | GRN | Driver's door open | Check for voltage to ground: There should be 1 V or less. |

- Faulty driver's door switch
- An open in the wire

Driver's door closed | Check for voltage to ground: There should be 5 V or more. |

- Faulty driver's door switch
- Short to ground

Q4 | LT GRN/RED | Front passenger's door open | Check for voltage to ground: There should be 1 V or less. |

- Faulty front passenger's door switch
- An open in the wire

Front passenger's door closed | Check for voltage to ground: There should be 5 V or more. |

- Faulty front passenger's door switch
- Short to ground

Q2 | GRN/WHT | Left or right rear door open | Check for voltage to ground: There should be 1 V or less. |

- Faulty rear door switch
- An open in the wire

Left or right rear door closed | Check for voltage to ground: There should be 5 V or more. |

- Faulty rear door switch
- Short to ground

Q8 · C8 · F1 | GRN/ORN · GRN/RED | Parking brake lever up | Check for voltage to ground: There should be 1 V or less. |

- Faulty parking brake switch
- An open in the wire

Parking brake lever up | Check for voltage to ground: There should be 5 V or more. |

- Faulty parking brake switch
- Short to ground

Q5 | BLU/RED | Ignition switch ON (II) driver's seat belt unbuckled. | Check for voltage to ground: There should be 1 V or less. |

- Faulty driver's seat belt switch
- Poor ground (G551)
- An open in the wire

Q6 | BLU/RED
P18 | RED | Trunk lid [tailgate] open | Check for voltage to ground: There should be 1 V or less. |

- Faulty trunk[tailgate]latch switch
- Poor ground (G601)
- An open in the wire

Trunk lid closed | Check for voltage to ground: There should be 5 V or more. |

- Faulty trunk[tailgate]latch switch
- Short to ground

X5 | RED/WHT | Ignition key is in the ignition switch | Check for voltage to ground: There should be 1 V or less. |

- Faulty ignition key switch
- Poor ground (G401)
- An open in the wire

Ignition key is out of the ignition switch | Check for voltage to ground: There should be 5 V or more. |

- Faulty ignition key switch
- Short to ground

[ ]: 5-door