How to - Headlight Relays

Discussion in 'Electrical Systems' started by BonzoHansen, Oct 12, 2007.

  1. Steve's 77

    Steve's 77 Veteran Member

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    I recently put in headlight relays. They control Hella h4's. I too chose the driver's side for convenience and feed from battery side via #8 wire. I show 12.3 volts both at the battery side and also at the end of the #12 wire feed on the driver's side to feed the relay's #30 pins. My low beams are too dim. The high beams are fine. When I disconnect the driver's side low beam the right side low beam comes to life at normal brightness. Reconnect and both are back to too dim condition. I have tried everything I can think of to remedy this. All work fine as expected, just low beams are too dim. Does anyone have an idea of what my problem is. I am not opposed whatsover to reconfiguring these relays to the battery side of the car but from what I understand the benefit of that would be to prevent voltage drop to the driver's side because of a long feed wire to the relays on that side. It doesn't appear from my readings that that is my problem. Beside, I have to wonder why the highs work fine but the lows are too low. I thought maybe the stock factory wire running across between the two lights controlling the low beams might be old and beat up, but I jumped in a replacement wire and to no avail the same thing. Any ideas?
     
    Last edited: Sep 26, 2012
  2. 78LT383

    78LT383 Veteran Member Lifetime Gold Member

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    It sounds like your grounds might be weak. Did you upgrade them too by chance? Can you check the voltage at the ground terminals relative to the negative battery post?
     
  3. Steve's 77

    Steve's 77 Veteran Member

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    I ran new grounds from the battery direct to the relays. I must agree though ,it sounds like you're on the right track. I believe this is minor, but I've tried so many things. Not to be too dumb though, I'm not sure I know exactly what you mean. Compare the grounds?? Thanks for your help.
     
  4. Steve's 77

    Steve's 77 Veteran Member

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    I need to revise one thing in my first post. I ran a #12 power wire. Not #8 as first stated. I wonder if that is too long a run for #12 wire to run across the front of the car to power the relays.
     
  5. BonzoHansen

    BonzoHansen Administrator Lifetime Gold Member

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    check head light grounds, the screw to the rad support with star washers. the connectors might be dirty/bad. the relay ground only flows milliamps, no need to run it to the battery.
     
  6. Aceshigh

    Aceshigh Veteran Member Lifetime Gold Member

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    Is this with the car running??

    If it is, your alternator could be shot, or wired incorrectly.
     
  7. 78LT383

    78LT383 Veteran Member Lifetime Gold Member

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    What he said!!!

    On the ground side, only a little bit of the current goes through the relays, the lions share goes through the headlight connectors into the harness grounds, which were marginal at best from GM for the sealed beam headlights. Some nice 14 AWG or better grounds
    would be smart, and check the voltage of the ground pins at the headlight connector relative to the negative battery terminal to ensure all connections are working properly.
     
  8. Steve's 77

    Steve's 77 Veteran Member

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    To answer your questions. The car is running. Sweet. Anyway...I may have grounding electrical systems a bit screwed up here. Thanks for the info re: relays and their grounding requirements. I know the necessity for clean and quality grounds from past experience. Knowing that, I ran that new ground directly from the battery, grounding both the drivers side headlight plug and the relays on the same wire thinking that there is no better ground than going directly back to the battery. The passenger side is grounded to the radiator support via the screw and star washer you mention Bonzo. The driver's side like I mentioned is bundled with the ground wires from the relays. NOw.....it seems to me that the bolt and star washer would not be as good a ground as what I am offering it now. BUT....it is a long run via #12 wire back to the battery....SO I jumped all those to the block and other places to see if that was the case still to no avail. That was yesterday. I need to wait until late afternoon when it gets dark to attempt your suggestions you guys or at least to test your suggestions and it will be quite evident at that time. The low beams were ok, just dim dim dim. I have to wonder why the high beams were ok.... I now have a few things to try and will report back in about 5 hours. Oh BTW I'm wondering if I should have followed the wiring diagram exactly which shows the headlight grounds immediately going to ground rather than the way I did it. I know now that the new ground I ran is not necessary to operate the relays.
     
  9. kenny77

    kenny77 Veteran Member Lifetime Gold Member

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    if you ran the ground back to the battery, well that's about as good as it gets. I'm thinking that the problem is in the low beam relay and circuit to and from it that you built/added.

    Another consideration may be the headlights themselves. Don't rule out one being defective in a way that shorts or drains that low beam circuit.



    I wasn't a fan of doing this mod by making up my own wiring and relays and such, so I bought the harness plug and play and ready to go. The fact that I have a whole new wiring harness in the car, I wanted to plug and play this mod...not cut and splice.

    http://www.ebay.com/itm/New-Headlight-Relay-Harness-Kit-for-Sealed-Beam-Halogen-H4-Brighter-Headlights-/200800781813?pt=Motors_Car_Truck_Parts_Accessories&hash=item2ec0a8c5f5&vxp=mtr

    There's a thread around here where I think Todd explains about the bulbs that he used. They were these.
    http://www.autozone.com/autozone/parts/XtraVision-Headlight/1977-Chevrolet-Camaro/_/N-inaz7Z9ci8c?itemIdentifier=123882_413425_0_

    I found that he was right, these were the best..hands down.
     
  10. Steve's 77

    Steve's 77 Veteran Member

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    Got It....u Wont Believe What I Did

    I really do appreciate the feedback and help. I must preface this by saying I started this last year and I thought it was done correctly. This year I didn;t drive it much at night so therefore I never really noticed my problem. I had junk Chinese headlights. I got the Hellas this year. I thought the Chinese junk were my problem. In the mean time the job and how I did what I did and why I did what I did wasn't really fresh in my mind.... You know what it was? I had my nice new Hella H4's and the nice new plugs, and my nice new relays and my nice new wiring BUT.... and I have no idea why now because it was last year....I hooked up the wires from the plug from the back of the lamps to the wrong wires. I just can't remember why I decided which wire was the ground which was the HIgh beam and which was low. I must have had some reason for this last year but I was wrong. I'm surprised they worked at all. Perhaps the standard stock equipment lamps are hooked up differently, I'm not sure. It just occured to me to do a search of that plug to verify the correct purpose of each lug on the plug and sure enough I had it all frigged up. I cannot explain now why I decided the purpose of each wire coming out of that plug but I must have had some reason for it. Man do I now have nice headlights. I certainly do appreciate the hand-holding.
     

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