Lo Beams, no beams, 12V at socket, WTF

Discussion in 'Mechanics Garage' started by whiteknuckles, Apr 22, 2017.

  1. whiteknuckles

    whiteknuckles New Member

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    Alrighty then. I have an '02 6th gen. No lo beams despite 12V at the connector. H4 bulb replacement yielded bupkis. Not the starter switch or the relay. Hi beams work fine.
    There's only about 10V at the socket connector until I fire the engine, then I get 12V, but headlights don't turn on. I checked the ground at the battery and it's good. Leads me to believe it's a lack of current, but I have no clue as to where to look next.
    Any ideas?
     
  2. V4toTour

    V4toTour New Member

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    Last edited: Apr 22, 2017
  3. V4toTour

    V4toTour New Member

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    Make / Models : Model/Build Years:
    HONDA / VFR800 2002-2005

    Manufacturer : HONDA (AMERICAN HONDA MOTOR CO.)

    NHTSA CAMPAIGN ID Number : 07V359000 Mfr's Report Date : AUG 14, 2007
    Component: ELECTRICAL SYSTEM:WIRING
    Potential Number Of Units Affected : 6952
    Summary:
    ON CERTAIN MOTORCYCLES, THE FRONT FAIRING SUB-HARNESS (SECTION OF THE WIRING HARNESS) TRANSFERS THE ELECTRICAL GROUNDING LOAD OF THE HEADLIGHTS, FRONT TURN SIGNALS, INSTRUMENT PANEL, AND VARIOUS RELAYS TO THE MAIN WIRING HARNESS VIA AN 18-PIN CONNECTOR. UNDER CERTAIN CONDITIONS, THE GROUND WIRE TERMINALS INSIDE THE CONNECTOR CAN OVERHEAT, RESULTING IN MELTING OF THE CONNECTOR AND A LOSS OF POWER TO VARIOUS CIRCUITS.
    Consequence:
    AS A RESULT, A LOSS OF CRITICAL LIGHTING OR ENGINE POWER COULD OCCUR WITHOUT WARNING, WHICH COULD CAUSE A CRASH.
    Remedy:
    DEALERS WILL INSTALL A RE-DESIGNED SUB-HARNESS. IF DAMAGE IS FOUND, THE MAIN WIRING HARNESS WILL ALSO BE REPLACED FREE OF CHARGE. THE RECALL IS EXPECTED TO BEGIN DURING SEPTEMBER 2007. OWNERS MAY CONTACT HONDA AT 1-866-784-1870.
    Notes:
    CUSTOMERS MAY ALSO CONTACT THE NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION┬┐S VEHICLE SAFETY HOTLINE AT 1-888-327-4236 (TTY 1-800-424-9153), OR GO TO HTTP://WWW.SAFERCAR.GOV.
     
  4. whiteknuckles

    whiteknuckles New Member

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    I appreciate all your input. I checked the voltage at the battery and the bulb connectors. I get 14V across the battery terminals with the engine running. I'm reading 12V at the lo beam connectors without a bulb. I checked to make sure the start push button is OK, the circuit goes from open to 1 ohm when pressed. The hi-lo beam switch was doused with contact cleaner and appears to be making mechanical connection. Hi beams work fine. I'm not sure where I would check the switch for continuity, maybe you do?
     
  5. whiteknuckles

    whiteknuckles New Member

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    Recall was done. Lo beam switch is OK. Interestingly, I get 12V at each light socket, but once I plug a bulb in on either connector, my voltage drops to 0V. Any ideas?
     
  6. stoshmonster

    stoshmonster New Member

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    The Blue wire with a White stripe coming from the starter switch is the signal power for both the high beam and low beam relays. That Blue wire with a White stripe goes directly to the low beam relay and energizes the coil in the low beam relay which in turn turns on your low beam lights and keeps them on at all times. Provided that the low beam relay is operating correctly and the supply power on the Black wire with a Red stripe is there and waiting to power the lights on.

    That same Blue wire with a White stripe also goes to the high beam switch in the left handset to energize the coil in the high beam relay when the high beam switch is flipped to the ON position. The high beam switch ONLY turns on the high beam lights and has absolutely nothing at all to do with the low beam lights because the Blue wire with a White stripe directly powers the signal side of the low beam relay right from the starter switch. So don't waste your time messing with the high beam switch Whiteknuckles you already know it works.

    With the key switch in the ON position,bike not started yet,you should be reading power on the White wire with a Black stripe in both low beam light bulb sockets. If you are this does not necessarily mean that you are getting ENOUGH power to light the bulbs. Mechanical relays fail in some very peculiar ways and this is one of them.

    The supply power busbar inside the low beam relay can be making a connection (which is why you would see a power reading on the White wire with a Black stripe with the key switch in the ON position) but simply not be making ENOUGH of a GOOD connection to power up the light bulbs (which is why you would see the power drop off with the bulb connected). I would suggest swapping the high beam and low beam relays around and see if the problem persists.
     

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  7. whiteknuckles

    whiteknuckles New Member

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    Looks like a bad connection at the blue harness. Unfortunately, it's intermittent, but it looks like there is only one wire in could be, that being the blue/white one that connects to the low beam relay. Let's see where this takes me.
     
  8. whiteknuckles

    whiteknuckles New Member

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    The bad connection is the black wire with a red stripe that is common to both hi and lo beam relays. After the harness connection, it goes on to the 20A headlight fuse. Any reason why I shouldn't just solder in a jumper wire to bypass the blue connector. The end point is the fuse, so I figure that'll blow if needs be. I really don't want to replace 2 harnesses for one bad connection.
     
    Last edited: Apr 23, 2017
  9. whiteknuckles

    whiteknuckles New Member

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    Well, jumped the black/red wire. Have low beams now, BUT NO HI BEAMS!!!!
     
  10. whiteknuckles

    whiteknuckles New Member

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    He he he. It helped to connect the hi beams to the harness... FIXED! for now.
     
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