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Technical Headlight Relays??

Discussion in 'The Hokey Ass Message Board' started by jaw22w, Dec 25, 2019.

  1. jaw22w
    Joined: Mar 2, 2013
    Posts: 1,064

    jaw22w
    Member
    from Indiana

    I recently changed headlights from the '27 stock style to the 682-C style headlights. I never had good headlights with the '27 style lights. So when I installed the new lights. I rewired the system to use relays with 10 ga wire all the way to the lights. Wow! do I ever have good lights now. Can't outrun 'em.
    The lighting system worked well for a few months...….. until the night before last. Went to take the wife out for dinner and look at the Christmas lights. Pulled the T out of the garage, pulled the light switch out and no lights. Changed cars out and went to dinner. Yesterday I got the T up on the lift (everything is underneath). Maxi fuse still good. Multimeter showed power in, but no power out of either relay with switch on. Without disconnecting anything, I took the bracket loose that holds the relays and turned it slightly to get a better look. I heard a click and the headlights came on. I put it all back together and the lights work properly now. Apparently one of the relays had stuck open. Everything works now, but for how long? With my luck, only until the next time I take it out at night.
    When I installed the relay system, I bought a cheap Chinese relay wiring harness. When it arrived, I cut one of the supposedly 10 ga wires. It was about 16-18 ga wire with thick insulation to look like 10 ga. So I threw away everything but the relays and built my own harness with real 10 ga wire. So now I figure the relays are really cheap junk, too. I don't want to trust them. The relays have no numbers except to identify the terminals, so I have no idea what they are. I can put an SBC together in my sleep, but when it comes to electrical, I'm not the sharpest crayon in the box. So what relays do I need? What is a good brand of relays? And where to get them? Thanks for any help. HEADLIGHTS.JPG
     
    dana barlow, KoolKat-57 and Tim like this.
  2. I like the Bosch relays....haven’t ruin one of them yet. I’ve had them in my light circuit out as close as possible to the lights for 15 years or more.
     
  3. lostone
    Joined: Oct 13, 2013
    Posts: 1,358

    lostone
    Member
    from kansas

    You sure it wasn't a ground problem ? You said you moved it around and it clicked and began working, just curious how you have them grounded.
     
  4. dalesnyder
    Joined: Feb 6, 2008
    Posts: 401

    dalesnyder
    Member

    I used a headlight relay from summit, same as others. It used a strange 4 pin rectangular relays. The relays did not last a week before they stuck on. I replaced them with the normal 5 pin square Bosch style relays and have had no further issues.
     
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  5. Hoptup32
    Joined: Aug 21, 2007
    Posts: 54

    Hoptup32
    Member

    For any critical electrical circuit that requires a relay, I would recommend using a top of the line quality relay, such as Bosch, Hella relays are also another brand name quality relay. I would also recommend only purchasing the 30 amp variety relays for general use. You can purchase the Bosch relays from a variety of places, Summit has them for about $5 each, which is what I would expect to pay for a good quality relay, the $2-3 relays would be of questionable quality in my mind, however, the cheaper relays would be borderline acceptable for any non-critical circuits that would require multiple relays. I've ordered Hella relays in the 70 amp variety from my local NAPA store.
    I've had the same Bosch brand relays on my headlight circuits and on my brake circuit since I rewired my car fifteen years ago. The brake relay alone cycles every time I press the brake pedal, which would amount to multiple thousands of cycles since it was first installed.
    I would definitely switch to a brand name relay for your headlight circuit.
     
  6. Truck64
    Joined: Oct 18, 2015
    Posts: 4,142

    Truck64
    Member
    from Ioway

    Bosch 5 terminal relay are the standard, available pretty much everwhere.
     
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  7. jaw22w
    Joined: Mar 2, 2013
    Posts: 1,064

    jaw22w
    Member
    from Indiana

    Thanks guys! I was kinda lost. I found the Bosch relays online. They will be here Saturday.
     
    Boneyard51 likes this.
  8. jaw22w
    Joined: Mar 2, 2013
    Posts: 1,064

    jaw22w
    Member
    from Indiana

    Well, I received my 2 Bosch relays yesterday. Replaced the 2 Chinese relays with the 2 new Bosch. Turn on the lights. Nothing happens! DAMMIT! Start checking. Find nothing wrong, but no lights. Swap the Chinese relays back in. Lights! What the hell? IMG_0596.JPG This is how the relays are wired. I simply copied the Chinese harness using real 10 ga wire. I could not find a diagram on the net that was wired the same, but it works with the original relays. The system will work with both Chinese relays. It also works with a Chinese relay in position A and a Bosch in position B.
    There are 16 possible combinations. It being a nasty rainy day I tried them all. It boils down to this:
    C= Chinese relay, B= Bosch relay, Position A and B per diagram
    Position A, Position B
    C, C Both Lights
    C, B Both Lights
    B, C Low beam only
    B, B NO LIGHTS
    (I can't make this space out like I wanted)

    It appears that the new Bosch relays don't have the 30 and 87A connected internally so no power goes to the second relay.
    I have always wired my own cars, so I am not a complete noob, but never had to mess with relays. so I could easily be wrong here. There are 2 possibilities here.
    1. I have the wrong Bosch relays.
    2. Both Bosch relays are defective. (I hate to believe this due to there shining reviews.)
    If the Bosch relays are the wrong ones for this application, can someone give me a correct Bosch part number for this application? Or are they defective?
    I think I could power the second relay with a wire T'ed into the power wire from the starter after the maxi fuse, couldn't I? I would rather not do it this way, though. I would rather get the right relays.
    I did find numbers on the Chinese relays. JD 1914 12v/80A
    The new Bosch are 0 332 019 150
    Both sets of relays have a little diagram on them which I don't understand, but the diagrams are different. I don't really know what this means. Also the Bosch center pin is only marked 87 while the Chinese is marked 87A.
    I've learned a lot about relays while researching in the last few days, but probably just enough to make me dangerous. Can anybody shed some light on this for me? Thanks.
    Hope you had a Merry Christmas! Have a happy New Year.
     
    Last edited: Dec 29, 2019
  9. jaw22w
    Joined: Mar 2, 2013
    Posts: 1,064

    jaw22w
    Member
    from Indiana

    I couldn't get a pic of the diagrams on the relays, so I drew them. Does this help?
    IMG_0597.JPG
     
  10. buick bill
    Joined: Dec 18, 2008
    Posts: 422

    buick bill
    Member
    from yreka;ca

    im not sure when relays are needed . I just rewired my 41 with a 40 yr. old stock replacement harness that came with the car . I converted it to 12v at the same time .no relay ever came on it , or with the new /old harness ,except horn . all works fine and the lights are very bright .the 6v harness does have heavy gauge wire , is a relay always needed? I was going to get better ?lights as my vision aint what it was , but ended up getting wally cheapoes . was glad I saved $200.oo the lights are great !??
     
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  11. jaw22w
    Joined: Mar 2, 2013
    Posts: 1,064

    jaw22w
    Member
    from Indiana

    Probably would get even better with the relays. The purpose of the relays is to eliminate voltage loss in long runs of wire. Short runs of 10 gauge wire deliver a lot more power to the lights. Believe me, my lights are at least 50 -75% better with the relay system, maybe more.
     
  12. TrailerTrashToo
    Joined: Jun 20, 2018
    Posts: 719

    TrailerTrashToo
    ALLIANCE MEMBER

    I see a couple of problems with this diagram.

    1. Does the Chinese relay have both a 87 and 87A pins?

    2. The Bosch pins should be labeled 87 and 87A

    Hold the Chinese and Bosch relays upside down and look at the pins. Are pins 30, 85, 86, 87 and 87A physically in the same location?

    With a multimeter, check the continuity between pins 85 and 86 (Testing for an open circuit in the relay coil)

    With a multimeter, check for continuity from pin 30 to both pins 87 and 87A (Verifying that the relay contacts are wired correctly)

    Good luck
     
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  13. jaw22w
    Joined: Mar 2, 2013
    Posts: 1,064

    jaw22w
    Member
    from Indiana

    Thanks for that. The Chinese relay has a pin marked 87 and the center pin marked 87a. The Bosch has a pin marked 87 and the center pin marked 87 also. Both Chinese and Bosch look exactly identical except for the pin labels and the small diagram on each (2nd pic).
    Both Chinese and Bosch show continuity between 85 and 86.
    Chinese has continuity from 30 to 87a. Bosch does not.
    Chinese has no continuity between 87 and center pin 87a. Bosch has continuity between 87 and center pin 87.
    That confirms my theory that the Bosch does not connect 30 to the 87 center pin , but does not answer the question of defective or wrong application. Does Bosch make a relay that connects 30 to the 87 center pin?
     
    Last edited: Dec 29, 2019
  14. Halfdozen
    Joined: Mar 8, 2008
    Posts: 606

    Halfdozen
    ALLIANCE MEMBER

    Bosch, Cole Hersee, Pico brands are good. Pico makes a version with a weatherpack style waterproof connector.
    The 60 amp versions use a 3/8" wide blade on the secondary side, you probably won't find 3/8 qd connectors at the usual automotive stores, they're widely available from places that sell electrical/ electronics bits.
     
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  15. Hoptup32
    Joined: Aug 21, 2007
    Posts: 54

    Hoptup32
    Member

    You are using the wrong Bosch relay. According to the part number you listed, you have a relay with dual 87 terminals and no 87a terminal. Thats why they won't work for Relay A in your wiring diagram.
    I think you can use those bosch relays if you connect the power wire (to Relay B) on Relay A from your labeled terminal 87a to the 30 terminal on Relay A, so that the 30 terminal on Relay A is jumped over to the 30 terminal on Relay B.
    The correct Bosch relay number would be 0 332 209 150.
     
  16. TrailerTrashToo
    Joined: Jun 20, 2018
    Posts: 719

    TrailerTrashToo
    ALLIANCE MEMBER

    The Chinese relay switches power from pin 87A to pin 87 when energized.

    The Bosch relay "appears" (I am making an assumption here) to be designed as an ON-OFF only relay. If you apply power and ground to 86 and 86, you should have continuity from 30 to 87A.

    If so, the wiring diagram will need to be reworked.

    First, the HI and LOW beam relays get wired separately (eliminate the connection between 87A and 30)

    Both relays get 12 Volts battery power at 30.

    Each headlight gets connected to 87A (Assuming 87a gets power when the relay is energized)

    Good luck - I'll be away from the computer for a while - My daughter's new (to her) house has a plumbing leak - fortunately on the drain side...
     
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  17. G-son
    Joined: Dec 19, 2012
    Posts: 664

    G-son
    Member
    from Sweden

    Not only in the wire, but also every splice, connector, switch and so on - and there can be MANY of those along the way from generator/battery to lamps (or whatever) in a system without relay(s). Avery item that adds a little bit of resistance causes the voltage to drop, and lamps are sensitive to voltage - a 5% drop in voltage will reduce light output about 20%.

    You can easily measure the voltage on the battery with the engine running, and compare it to the voltage on the lamp (lamp still connected, you need the current draw for a correct reading). The bigger drop, the more light you loose - on the other hand you gain lamp life on reduced voltage. Compromizes, compromizes.
     
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  18. buick bill
    Joined: Dec 18, 2008
    Posts: 422

    buick bill
    Member
    from yreka;ca

    ive always thought it was to take load off the switch . I guess it helps in many ways . led probably needs no relays ? just deep pockets !
     
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  19. jaw22w
    Joined: Mar 2, 2013
    Posts: 1,064

    jaw22w
    Member
    from Indiana

    Thank you very much Hoptup32! I found the correct 0 332 209 150 relay on Amazon. Confirmed it is the 87A type, not the 87 type. 2 on the way. That will fix me right up.
     
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  20. G-son
    Joined: Dec 19, 2012
    Posts: 664

    G-son
    Member
    from Sweden

    Basically correct. Reducing the current through the switch also reduces the heat in the switch if/when the connection inside the switch is bad, as when the old contact surfaces have been oxidized (the contact is never perfect, there's always some resistance). The switch may be fine handling the low current to control a relay (or two, or more), but with the full load of the lamps the old oxidized (or undersized) switch may heat up and sooner or later get destroyed - worst case causing a fire in the process.

    LED may or may not need relays, the very low power LED tail lights should not need much to handle the current, while auxillary LED lights drawing hundreds of watts need a really good supply.
     
  21. Relays are needed to control a high current circuit, such as headlights, horn, fuel pump, etc., with a low current circuit. Without a relay, all of the current to run an item has to go through the switch. With a relay, all you have to do is close the relay with the switch.


    Sent from my iPhone using The H.A.M.B. mobile app
     
  22. jaw22w
    Joined: Mar 2, 2013
    Posts: 1,064

    jaw22w
    Member
    from Indiana

    I am thoroughly convinced of the merits of a relay headlight system after installing mine. As I said earlier I bought a complete plug in wire harness kit from ebay. I think it was $18. I ended up throwing the whole thing away and copying the harness in 10 ga. I bought 2 wrong relays to replace the Chinese relays, then bought 2 right relays and I still have less than $50 in the relay system. I don't think there is a cheaper, more efficient upgrade around for your headlights.
     
  23. Joe H
    Joined: Feb 10, 2008
    Posts: 946

    Joe H
    Member

    Not really headlight related, but at we had a new bed put on an older Ford pickup. The bed uses LED tail lights and running light. The installers wire the box up through the trailer harness. The truck now doesn't know the tail / turn / stop lights are working due to the very low amp draw of the LEDs, the front incandescent bulbs flash really fast as an indicator the rears are not working.
    It just points out the really small amp draw of LEDs, I doubt LED headlamps would need relays or even big wire to work right.

    Good job on the headlights, you can never have enough light!
     
    joel likes this.
  24. Rusty J
    Joined: Nov 25, 2019
    Posts: 45

    Rusty J
    Member

    Check out the wiring on newer cars - relays all over, which allows the use of smaller stranded wire to supply power to things - but here's the catch: If you look at most aftermarket wire harnesses the individual strands of wire are thicker (and fewer) than oem harnesses which have more and smaller gauge strands of wire - more efficient in the world of electronics. When converting to LED lights that hook up to the flashers you need to include a resistor in the circuit to supply adequate load. Education is expensive when we learn by making mistakes and then figure out how to correct them (that's why my bank account doesn't like me much)
     
    firstinsteele likes this.
  25. Boneyard51
    Joined: Dec 10, 2017
    Posts: 4,346

    Boneyard51
    Member

    The lights on the bed will not work right if wired through the auxiliary trailer wiring. They should have used the original tail lite/ turn signal wiring! But that uncut/ unused trailer wiring laying there is tempting to use! I know I used to out fit new trucks with hydraulic hay beds! A back yard fix to get the LED turn signals to work slower is to wire another incandescent built in each turn signal circuits. Backyard, but works. Cheaper than reprogramming!






    Bones
     
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  26. DOCTOR SATAN
    Joined: Mar 21, 2014
    Posts: 711

    DOCTOR SATAN
    Member
    from okc

    No relay in daily driven A coupe, bright as ever, even grounded at the light...
     
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  27. I buy Bosch relays and plug pigtails by the handful, use them all over my cars. Inexpensive, never fail, makes no sense to do it any other way in my never to be humble opinion. And I use more reliable electronic flasher units on LED tail lights. Hint, blue dots are opaque to LED lights!
     
  28. Halfdozen
    Joined: Mar 8, 2008
    Posts: 606

    Halfdozen
    ALLIANCE MEMBER

    Another thing to consider:
    OEM light switches have an internal circuit breaker, in the event of excess current draw the breaker will cycle on and off, which is better than having a fuse blow and leave you entirely without headlights suddenly.
    I use a single 60 amp relay to supply headlights, 30 amp inline breaker on secondary side of relay, light switch switches primary side, dimmer switch chooses high or low beam.

    Edit: Re led lights for signals, you can buy an electronic flasher that'll plug into the same socket as a conventional one, it has a ground wire, prevents erratic signal function.
     
    olscrounger likes this.
  29. Rusty J
    Joined: Nov 25, 2019
    Posts: 45

    Rusty J
    Member

    Daniel stern lighting - tech articles should have info you need - I used the schematics for relays in designing my electrical setup in my car.
     
  30. Be sure the relay you get is designed for continuous use (like lights) and not intermittent (like a horn). By the way, where was the one that failed designed to be used?

    Charlie Stephens
     

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