Control Unit Input Test

Before testing, troubleshoot the multiplex control system (see TROUBLESHOOTING ).
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 4.
  DRIVER'S UNDER-DASH FUSE/RELAY BOX SOCKET (Driver's multiplex control unit connector A)
  
  Fig 1: Identifying Driver's Under-Dash Fuse/Relay Box Socket Connector Terminals
  Courtesy of AMERICAN HONDA MOTOR CO., INC.
  
  DRIVER'S MULTIPLEX CONTROL UNIT CONNECTOR B
  
  Fig 2: Identifying Driver's Multiplex Control Unit Connector B Terminals
  Courtesy of AMERICAN HONDA MOTOR CO., INC.
  
  DRIVER'S UNDER-DASH FUSE/RELAY BOX CONNECTOR E GRN/ORN
  
  Fig 3: Identifying Driver's Under-Dash Fuse/Relay Box Connector E GRN/ORN Terminals
  Courtesy of AMERICAN HONDA MOTOR CO., INC.
  
  DRIVER'S UNDER-DASH FUSE/RELAY BOX CONNECTOR M RED/BLK
  
  Fig 4: Identifying Driver's Under-Dash Fuse/Relay Box Connector M RED/BLK Terminals
  Courtesy of AMERICAN HONDA MOTOR CO., INC.

Reconnect the driver's multiplex control unit to the driver's under-dash fuse/relay box, 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 CONNECTOR TO FUSE/RELAY BOX INDEX ).

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.

DRIVER'S UNDER-DASH FUSE/RELAY BOX SOCKET (DRIVER'S MULTIPLEX CONTROL UNIT CONNECTOR A) RESULT CHART

Cavity

Wire

Test condition

Test: Desired result

Possible cause if result is not obtained

B11⁽¹⁾

BLK

Under all conditions

Check for voltage to ground: There should be less than 1 V.

Poor ground (G501)
An open in the wire

GRN/ORN

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

BLU/BLK

Ignition key is in the ignition switch

Check for voltage to ground: There should be 1 V or less.

Faulty ignition 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 switch
Short to ground

RED/BLK

Combination light switch ON

Check for voltage to ground: There should be battery voltage.

Blown No. 10 (15 A) fuse in the passenger's under-dash fuse/relay box
Faulty taillight relay
Faulty combination light switch
Faulty driver's under-dash fuse/relay box
An open in the wire

⁽¹⁾	Multiplex control unit connector B

Remove the driver's multiplex control unit from the driver's multiplex control unit and make these input tests at the connector and driver's under-dash fuse/relay box sockets.

If any test indicates a problem, find and correct the cause, then recheck the system.

If all the input tests prove OK, go to gauge assembly input test (see GAUGE ASSEMBLY INPUT TEST ).

GAUGE ASSEMBLY INPUT TEST RESULT CHART

Cavity	Wire	Test condition	Test: Desired result	Possible cause if result is not obtained
A24	Fuse/relay box socket	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 fuse/relay box
A12		Under all conditions	Check for voltage to ground: There should be battery voltage.	Blown No. 13 (7.5 A) fuse in the passenger's under-dash fuse/relay box An open in the wire
A1		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 ignition key light An open in the wire

* 1: Multiplex control unit connector B