LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Honda >> 2007 >> Ridgeline RTX >> Repair and Diagnosis >> External Pages >> Different car >> Section 62 (Keyless/Power Door Locks/Security System) >> Control Unit Input Test
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Control Unit Input Test

WARNING: This page is about a different car, the 2008 Honda Pilot, 2007 Honda Pilot, and 2006 Honda Pilot. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: These tests cover the door, driver's, and passenger's multiplex control units.
  1. Before testing the power door lock and security control functions, troubleshoot the multiplex control system (see TROUBLESHOOTING ).

    Driver's Unit 

  2. Remove the driver's multiplex control unit from the driver's under-dash fuse/relay box.
  3. 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.
      Fig 1: Identifying Driver's Multiplex Control Unit Connector Terminals
      G04247346Courtesy of AMERICAN HONDA MOTOR CO., INC.
  4. With the driver's multiplex control unit still disconnected, 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 step  5.
      TERMINALS REFERENCE TABLE

      Cavity Wire Test condition Test: Desired result Possible cause if result is not obtained
      A12 Fuse/relay box socket Under all conditions Measure the voltage to ground: There should be battery voltage.
      • Blown No. 13 (7.5 A) fuse in the passenger's under-dash fuse/relay box
      • Faulty driver's fuse/relay box
      • An open in the wire
      A24 Ignition switch ON (II) Measure the 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
      A5(1) Under all conditions Attach to ground: The security indicator should come on.
      • Blown No. 13 (7.5 A) fuse in the passenger's under-dash fuse/relay box
      • Faulty security indicator
      • Faulty driver's fuse/relay box
      • An open in the wire
      A22(1) Connect B16 to battery voltage and A22 to ground The parking lights and dash lights should come on.
      • Blown No. 10 (15 A) fuse in the passenger's under-dash fuse/relay box
      • Faulty taillight relay
      • Faulty driver's fuse/relay box
      • An open in the wire
      B16(1) RED/GRN Combination light switch OFF Check for continuity to ground: There should be no continuity.
      • Faulty taillight relay
      • Faulty combination light switch
      • Faulty driver's fuse/relay box
      • An open in the wire
      • A short to ground in the wire
      Combination light switch ON and jump B16 to battery voltage The parking lights and dash lights should come on.
      • 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 fuse/relay box
      • An open in the wire
      (1) Except LX and LX-VP models
  5. 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 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  6.
      TERMINALS REFERENCE TABLE

      Cavity Wire Test condition Test: Desired result Possible cause if result is not obtained
      B2(1) GRN/BLK Wake up the multiplex system by locking all doors and tailgate with the power door lock switch; Left rear door lock knob switch unlocked Measure the voltage to ground: There should be less than 1 V.
      • Poor ground (G601)
      • Faulty left rear door lock knob switch
      • An open in the wire
      Wake up the multiplex system by locking all doors and tailgate with the power door lock switch; Left rear door lock knob switch locked Measure the voltage to ground: There should be 5 V or more.
      • Faulty left rear door lock knob switch
      • A short to ground in the wire
      B6(1) YEL Hood open Measure the voltage to ground: There should be less than 1 V.
      • Poor ground (G201)
      • Faulty hood switch
      • An open in the wire
      Hood closed Measure the voltage to ground: There should be 5 V or more.
      • Faulty hood switch
      • A short to ground in the wire
      B8 ORN Tailgate open Measure the voltage to ground: There should be less than 1 V.
      • Poor ground (G652)
      • Faulty tailgate latch switch
      • An open in the wire
      Tailgate closed Measure the voltage to ground: There should be 5 V or more.
      • Faulty tailgate latch switch
      • A short to ground in the wire
      E3 GRN/ORN Driver's door open Measure the voltage to ground: There should be less than 1 V.
      • Faulty driver's door switch
      • An open in the wire
      Driver's door closed Measure the voltage to ground: There should be 5 V or more.
      • Faulty driver's door switch
      • A short to ground in the wire
      E10 LT GRN/BLK Left rear door open Measure the voltage to ground: There should be less than 1 V.
      • Faulty left rear door switch
      • An open in the wire
      Left rear door closed Measure the voltage to ground: There should be 5 V or more.
      • Faulty left rear door switch
      • A short to ground in the wire
      M9 BLU/BLK Ignition key is in the ignition switch Measure the voltage to ground: There should be 5 V or more.
      • Poor ground (G401)
      • Faulty ignition key switch
      • An open in the wire
      Ignition key is out of the ignition switch Measure the voltage to ground: There should be less than 1 V.
      • Faulty ignition key switch
      • A short to ground in the wire
      B11 BLK Under all conditions Measure the voltage to ground: There should be less than 1 V.
      • Poor ground (G501)
      • An open in the wire
      (1) Except LX and LX-VP models

      Passenger's Unit 

  6. Remove the passenger's multiplex control unit from the passenger's under-dash fuse/relay box, and disconnect its connector.
  7. 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  8.
      Fig 2: Identifying Passenger's Multiplex Control Unit Connector Terminals
      G04247347Courtesy of AMERICAN HONDA MOTOR CO., INC.
  8. With the passenger's multiplex control unit still disconnected, make these input tests at the connectors and the passenger'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 step  9.
      TERMINALS REFERENCE TABLE

      Cavity Wire Test condition Test: Desired result Possible cause if result is not obtained
      A8 Fuse/relay box socket Under all conditions Check for continuity to ground: There should be continuity.
      • Poor ground (G651)
      • Faulty passenger's fuse/relay box
      • An open in the wire
      A9 Under all conditions Attach to ground: Horns should sound.
      • Blown No. 47 (20 A) fuse in the under-hood fuse/relay box
      • Faulty passenger's fuse/relay box
      • Faulty horn relay
      • Faulty horn
      • An open in the wire
      A20 Under all conditions Attach to ground: Headlights should come on.
      • Faulty headlight relay 1 or 2
      • Faulty passenger's fuse/relay box
      • An open in the wire
      A22 Ignition switch ON (II) Measure the 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
      • Faulty passenger's fuse/relay box
      • An open in the wire
      A23 Under all conditions Measure the voltage to ground: There should be battery voltage.
      • Blown No. 12 (20 A) fuse in the passenger's under-dash fuse/relay box
      • Faulty passenger's fuse/relay box
      A24 Under all conditions Measure the voltage to ground: There should be battery voltage.
      • Blown No. 13 (7.5 A) fuse in the passenger's under-dash fuse/relay box
      • Faulty passenger's fuse/relay box
      A10 Fuse/relay box socket Jump A10 to battery voltage and B11 to body ground. Check driver's door lock operation:
      The door should lock.
      • Faulty driver's door lock actuator
      • Faulty passenger's fuse/relay box
      • An open in the wire
      B11(1) YEL
      A10 Fuse/relay box socket Jump A10 to battery voltage and A11 to body ground. Check passenger's doors lock operation: The doors should lock.
      • Faulty passenger's door lock actuator
      • Faulty passenger's fuse/relay box
      • An open in the wire
      A11 Check tailgate lock operation: The tailgate should lock.
      • Faulty tailgate lock actuator
      • Faulty passenger's fuse/relay box
      • An open in the wire
      B21 BLU Under all conditions Check for continuity to ground: There should be continuity.
      • Poor ground (G504)
      • Faulty connections at the audio unit, DVD player, rear controller and screen, navigation display unit
      • Faulty audio unit, DVD player unit, rear controller and screen, navigation display unit
      • Faulty passenger's fuse/relay box
      • An open in the wire
      (1) Except LX and LX-VP models
  9. Reconnect the passenger's multiplex control unit to the passenger's under-dash fuse/relay box, and perform the following input tests at the appropriate connectors on the passenger's under-dash fuse/relay box. For passenger's under-dash fuse/relay box connector socket location (see PASSENGER'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  10.
    TERMINALS REFERENCE TABLE

    Cavity Wire Test condition Test: Desired result Possible cause if result is not obtained
    C8(1) RED/BLU
    NOTE: Front passenger's door lock knob switch in the locked position
    		 Wake up the multiplex system by locking all doors and tailgate with the power door lock switch; Right rear door lock knob switch unlocked Measure the voltage to ground: There should be less than 1 V.
    • Poor ground (G651)
    • Faulty right rear door lock actuator
    • An open in the wire
    Wake up the multiplex system by locking all doors and tailgate with the power door lock switch; Right rear door lock knob switch locked Measure the voltage to ground: There should be 5 V or more.
    • Faulty right rear door lock actuator
    • A short to ground in the wire
    E2 GRN/RED
    NOTE: Right rear door lock knob switch in the locked position
    		 Wake up the multiplex system by locking all doors and tailgate with the power door lock switch; Front passenger's door lock knob switch unlocked Measure the voltage to ground: There should be less than 1 V.
    • Poor ground (G651)
    • Faulty front passenger's door lock actuator
    • An open in the wire
    Wake up the multiplex system by locking all doors and tailgate with the power door lock switch; Front passenger's door lock knob switch locked Measure the voltage to ground: There should be 5 V or more.
    • Faulty front passenger's door lock actuator
    • A short to ground in the wire
    B2 BLU Under all conditions Measure the voltage to ground: There should be battery voltage.
    • Poor ground (G504)
    • Poor connection at audio unit, DVD player, rear controller and screen, navigation display unit
    • Faulty audio unit, DVD player unit, rear controller and screen, navigation display unit
    • An open in the wire
    B22 BLK Under all conditions Measure the voltage to ground: There should be less than 1 V.
    • Poor ground (G503)
    • Faulty passenger's fuse/relay box
    • An open in the wire
    (1) Except LX and LX-VP models
    TERMINALS REFERENCE TABLE

    Cavity Wire Test condition Test: Desired result Possible cause if result is not obtained
    C14 GRN/WHT Right rear door open Measure the voltage to ground: There should be less than 1 V.
    • Faulty right rear door switch
    • An open in the wire
    Right rear door closed Measure the voltage to ground: There should be 5 V or more.
    • Faulty right rear door switch
    • A short to ground in the wire
    C16 WHT/GRN Front passenger's door open Measure the voltage to ground: There should be less than 1 V.
    • Faulty front passenger's door switch
    • An open in the wire
    Front passenger's door closed Measure the voltage to ground: There should be 5 V or more.
    • Faulty front passenger's door switch
    • A short to ground in the wire
    E5 BLU/ORN Front passenger's door lock switch in UNLOCK Measure the voltage to ground: There should be less than 1 V.
    • Poor ground (G651)
    • Faulty front passenger's door lock switch
    • An open in the wire
    Front passenger's door lock switch in neutral position Measure the voltage to ground: There should be 5 V or more.
    • Faulty front passenger's door lock switch
    • A short to ground in the wire
    E6 BLK/ORN Front passenger's door lock switch in LOCK Measure the voltage to ground: There should be less than 1 V.
    • Poor ground (G651)
    • Faulty front passenger's door lock switch
    • An open in the wire
    Front passenger's door lock switch in neutral position Measure the voltage to ground: There should be 5 V or more.
    • Faulty front passenger's door lock switch
    • A short to ground in the wire

    Door Unit 

  10. Remove the door multiplex control unit, and disconnect its connector.
  11. Inspect the connector and socket terminals to be sure they are 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  12.
      Fig 3: Identifying Door Multiplex Control Unit Connector Terminals
      G04247348Courtesy of AMERICAN HONDA MOTOR CO., INC.
  12. Reconnect the connector to the control unit, and 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  13.
    TERMINALS REFERENCE TABLE

    Cavity Wire Test condition Test: Desired result Possible cause if result is not obtained
    A1 WHT/RED Under all conditions Measure the 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
    A12 BLK Under all conditions Measure the voltage to ground: There should be less than 1 V.
    • Poor ground (G401)
    • An open in the wire
    A6(1) BLU/WHT Driver's door key cylinder switch in LOCK Measure the voltage to ground: There should be less than 1 V.
    • Faulty driver's door key cylinder switch
    • Poor ground (G401)
    • An open in the wire
    • Short to ground in the wire
    Driver's door key cylinder switch in the neutral position Measure the voltage to ground: There should be 5 V or more.
    Driver's door key cylinder switch in UNLOCK Measure the voltage to ground: There should be 5 V or more.
    A16 BLU Driver's door key cylinder switch in UNLOCK Measure the voltage to ground: There should be less than 1 V.
    • Faulty driver's door key cylinder switch
    • Poor ground (G401)
    • An open in the wire
    • Short to ground in the wire
    Driver's door key cylinder switch in the neutral position Measure the voltage to ground: There should be 5 V or more.
    Driver's door key cylinder switch in LOCK Measure the voltage to ground: There should be 5 V or more.
    A7 PNK Driver's door lock knob locked Measure the voltage to ground: There should be less than 1 V.
    • Faulty driver's door lock actuator
    • Poor ground (G401)
    • An open in the wire
    Driver's door lock knob unlocked Measure the voltage to ground: There should be 5 V or more.
    • Faulty driver's door lock actuator
    • Short to ground in the wire
    A17 BLK/RED Driver's door lock knob unlocked Measure the voltage to ground: There should be less than 1 V.
    • Faulty driver's door lock actuator
    • Poor ground (G401)
    • An open in the wire
    Driver's door lock knob locked Measure the voltage to ground: There should be 5 V or more.
    • Faulty driver's door lock actuator
    • Short to ground in the wire
    A8 BLK/WHT Driver's door lock switch in LOCK Measure the voltage to ground: There should be less than 1 V.
    • Faulty driver's door lock switch
    • Poor ground (G401)
    • An open in the wire
    Driver's door lock switch in the neutral position Measure the voltage to ground: There should be 5 V or more.
    • Faulty driver's door lock switch
    • Short to ground in the wire
    A8 BLK/WHT Driver's door lock switch in LOCK Measure the voltage to ground: There should be less than 1 V.
    • Faulty driver's door lock switch
    • Poor ground (G401)
    • An open in the wire
    Driver's door lock switch in the neutral position Measure the voltage to ground: There should be 5 V or more.
    • Faulty driver's door lock switch
    • Short to ground in the wire
    (1) Except LX and LX-VP models
  13. If all the input tests prove OK, one of the control units must be faulty. Substitute a known-good control unit for the one that is most likely at fault, then recheck the system. If the system works properly, the original control unit is faulty; replace it. If there is still a malfunction, substitute a known-good control unit for the next most likely unit to be at fault, and recheck. If the system works properly, the original unit is faulty; replace it.
scientia non olet · About LEMON Manuals