Driver's Multiplex Control Unit

Remove the driver's multiplex control unit from the driver's under-dash fuse/relay box.
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 step 3.
  
  Fig 1: Identifying Driver's Under-Dash Fuse/Relay Box Socket
  Courtesy of AMERICAN HONDA MOTOR CO., INC.
  
  Fig 2: Identifying Driver's Under-Dash Fuse/Relay Box Connector E
  Courtesy of AMERICAN HONDA MOTOR CO., INC.
  
  Fig 3: Identifying Driver's Under-Dash Fuse/Relay Box Connector M
  Courtesy of AMERICAN HONDA MOTOR CO., INC.

With the driver's multiplex control unit still disconnected, make these input tests at the connector or driver's under-dash fuse/relay box socket.

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 4.

Test condition and Test Desired result chart

Cavity	Wire	Test condition	Test: Desired result	Possible cause if result is not obtained
A1	Fuse/relay box socket	Under all conditions	Attach to ground: The ignition key light should come on.	Blown No. 47 (20 A) fuse in the under-hood fuse/relay box Faulty LED An open in the wire
A24		Ignition switch ON (II)	Check for voltage to ground: There should be battery voltage.	Blown No. 9 (10 A) fuse in the driver's under-dash fuse/relay box Faulty driver's under-dash fuse/relay box
A6		Combination light switch ON	Check for voltage to ground: There should be battery voltage.	Blown No. 54 (10 A) fuse in the under-hood fuse/relay box Blown No. 10 (15 A) fuse in the passenger's under-dash fuse/relay box Faulty taillight relay Faulty combination light switch An open in the wire

Reconnect the driver's multiplex control unit to the driver's under-dash fuse/relay box, turn the ignition switch ON (II) to keep the system awake, and perform the following input tests at the appropriate connectors on the back of the driver's under-dash fuse/relay box. For driver's under-dash fuse/relay box connector socket location (see DRIVER'S 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, go to step 1 in PASSENGER'S MULTIPLEX CONTROL UNIT .

TEST CONDITION AND TEST DESIRED RESULT CHART

Cavity	Wire	Test condition	Test: Desired result	Possible cause if result is not obtained
E3	GRN/ORN	Driver's door open	Check for voltage to ground: There should be less than 1 V.	Faulty driver's door switch An open in the wire A short to ground
E3	GRN/ORN	Driver's door closed	Check for voltage to ground: There should be 5 V or more.
M3	RED/BLK	Combination light switch ON	Check for voltage to ground: There should be battery voltage.	Blown No. 54 (40 A) fuse in the under-hood fuse/relay box Blown No. 10 (15 A) fuse in the passenger's under-dash fuse/relay box Faulty taillight relay Faulty combination light switch An open in the wire
M9	BLU/WHT	Ignition key is in the ignition switch	Check for voltage to ground: There should be less than 1 V.	Poor ground (G401) Faulty ignition switch An open in the wire A short to ground
M9	BLU/WHT	Ignition key is out of the ignition switch	Check for voltage to ground: There should be 5 V or more.
E10	LT GRN/ BLK	Left rear door open	Check for voltage to ground: There should be less than 1 V.	Faulty left rear door switch An open in the wire A short to ground
E10	LT GRN/ BLK	Left rear door closed	Check for voltage to ground: There should be 5 V or more.