Entry Light Control System (Multiplex Control Unit) Input Test

1.Before testing, troubleshoot the multiplex control system.

2.Remove the dashboard lower cover.

3.Disconnect the under-dash fuse/relay box connectors.

NOTE: All connectors are wire side of female terminals.

 

4.Inspect the connector and socket terminals to be sure they are all making good contact.

  • If the terminals are bent, loose or corroded, repair them as necessary, and recheck the system.
  • If the terminals look OK, go to 5.

5.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 5.

Cavity Wire Test condition Test: Desired result Possible cause if result is not obtained 
K2 BLU/ORN Under all conditions Check for continuity between the K2 terminal and the keyless receiver unit 5P connector No. 2 terminal:
There should be continuity. 
  • An open in the wire
 
X8 WHT/BLK Under all conditions Attach to ground:
Ignition key light should come on. 
  • Blown No. 3 (15A) fuse in the under-hood fuse/relay box
  • Faulty ignition key light
  • An open in the wire
 

6.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 
P18 RED Tailgate lid open Check for voltage to ground:
There should be 1 V or less. 
  • Faulty tailgateswitch
  • An open in the wire
 
Tailgate closed Check for voltage to ground:
There should be 5 V or more. 
  • Faulty tailgate switch
  • Short to ground
 
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
 
Left (right) rear door open Check for voltage to ground:
There should be 1 V or less. 
  • Faulty left (right) rear door switch
  • An open in the wire
 
Left (right) rear door closed Check for voltage to ground:
There should be 5 V or more. 
  • Faulty left (right) rear door switch
  • Short to ground
 
X5 RED/WHT Ignition key inserted into the ignition switch Check for voltage to ground:
There should be 1 V or less. 
  • Poor ground (G401)
  • Faulty ignition key switch
  • An open in the wire
 
Ignition key removed from the ignition switch Check for voltage to ground:
There should be 5 V or more. 
  • Faulty ignition key switch
  • Short to ground
 
Y8 YEL/RED Driver's door lock knob switch locked Check for voltage to ground:
There should be 1 V or less. 
  • Poor ground (G501)
  • Faulty driver's door lock knob switch
  • An open in the wire
 
Driver's door lock knob switch unlocked Check for voltage to ground:
There should be 5 V or more. 
  • Faulty driver's door lock knob switch
  • Short to ground
 
O7 GRN/RED Ceiling light switch in middle position, all door closed Attach to ground:
Ceiling light(s) should come on. 
  • Blown No. 3 (15A) fuse in the under-hood fuse/relay box
  • Blown bulb
  • Faulty ceiling light
  • An open in the wire