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tamo3

'75 280Z Headlight Relay Upgrade

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    Hi,

     

    I try to find out how I can add relay for '75 280z.

    When I googled, I only find this one might be accurate info.

    http://forums.hybridz.org/topic/91938-headlight-relay-for-260-280/

    post-24248-0-31833700-1415939459_thumb.j

     

    When I trace FSM headlight diagram looks like this.

     

    post-24248-0-81622800-1415939042_thumb.j

     

     

     

    I'd like to add two relays. I'm not sure this is the correct way to add relay.

    Could you give me advice?

     

    post-24248-0-65467300-1415939052_thumb.j

     

    Thanks in advance,

    tamo3

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    I prefer to bring the new positive lead into the 87 pin. If you bring it into the 30 pin, then the 87a pin is hot when the headlights are off, giving you a chance to short circuit and blow the headlight fuse. Otherwise, the second drawing is correct. I hope the picture below helps some more.

    headlight-circuit.jpg

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    I notice that nobody has a relay between the headlight power switch and the fuse box fuses EDIT - as another option.  The switch is the part that tends to get pitted and hot and cause the solder joint to break.

     

    I put a relay in front of the fuse box to take the load off of the headlight power switch.  It's easy to get to for 1976, it's the red wire at the fuse box that feeds the two headlight fuses.  Looks the same for 1975.  I assume that for 1975 you would have to use the shunt supply to keep the ammeter working right, basically replacing the headlight switch with a more durable switch (the relay).  76 has a voltmeter so I just ran a fused line from the battery.

     

    I also did the same for the running lights but it was more difficult.  The wires are buried up in the dash.

     

    I had a pretty big voltage drop across the switch and eventually both solder joints, HL and running lights, broke/melted.  The contacts in the switch had matching pits and bumps making for a tiny contact area.

     

    Edit 2 - the two relay way would be best for taking the load off both supply and the dimmer.  I went with the one, in the cabin, because it was easy and I didn't really see any problems with the dimmer switch.  I wonder if the dimmer contacts really are much of a problem in the circuit?

    post-19298-0-26013000-1415988665_thumb.p

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    Interesting thought. You would have to intercept the R & RY wires coming out of the fusebox at the connector and send them to the 85 pin. Connect the 86 pins to the high/low beam switch. Then you could connect the R & RY wires downstream to fuses and to the battery. Have the 87 pins on the relays hooked to the RB & RW wires that were removed from the high/low beam switch and ground the 30 pins.

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    Thanks all the feedback.

     

    SteveJ,

    Thanks for jump in and reviewing my drawing. However, I'm a bit confused your information.

    High bean(RW), Low bean(RB) connect to 30pin, then RW and RB connect to 86pin?

    Ground center wire(R and RY), then R to 85pin?

     

    Hardway, 

    I use Adobe Illustrator to draw the lines.

     

    zKars,

    Thanks for simplify schematic. That's looks good and better than mine, I think.

    I found similar schematic not specific to 280z.

    http://smg.photobucket.com/user/h4lights/media/headlightRelay240Z.gif.html

    http://forums.pelicanparts.com/uploads18/944+headlight+relay+harness1289593946.jpg

    http://www.jeepfan.com/projects/HeadlightRelay/relaycircuit.jpg

    http://www.geocities.co.jp/MotorCity-Circuit/1623/01vmax_images/07hlb/hlb_kairozu.gif

     

    Zed Head,

    Interesting idea.

    I think dimmer connection is for mainly earthing for the main switch if you run wire what zKars suggested.

    Adding those two relay will avoid going high Amp through headlight switch and directly run high amp to the head light.

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    I was just suggesting the simplest way to get rid of the main problem with the headlight circuit.  The switch on top of the steering column, with its old, pitted contacts.   I have a single relay that only bypasses the headlight power switch.  I left the dimmer switch intact since it doesn't seem to be a problem, besides getting stuck open occasionally (in the past for me, no problems since).  I'm just being super-economical.

     

    Looks like there are many ways to take the power switch (supply), and the dimmer switch (ground), and the old wires out of the circuit and replace them with new.  

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    Here is the update of the schematic.

     

    attachicon.gif75-280z-headlight_v3.jpg

    Hi Tamo,

    I like you circuit diagram. Clear and easy to follow.

    There is omly one thing I would add to it. More for safety than anything else. Please don't take it as knocking what you have done. I like it a lot and may just follow your steps.

    I see you are using one 30A fuse to power the high and low beam circuits. I would prefer to use two seperate fuses. Just don't like the thought of cruising down the road doing 140kmh and all of a sudden have to "feel" my way in the dark.

    Looking forward to seeing photos of the finished work.

    Chas

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    Hi Zed Head,

     

    I totally agree with you. There are many way to solve the problem with adding relay. Since my car is under construction, remove all dash, I think this is great opportunity to upgrade. When I had 240z, I felt the headlight was so dark. For my 280z, I haven't drive the car yet LOL. Once complete rebuilding, I will start working on the replay upgrade. My plan is similar approach with you. Simple way.

     

    I assume I can just cut and add some wire in engine bay to add relays :-)

     

    Hi Chas,

     

    Thanks for the good advice. I originally put 30Amp fuse for each relay, but when I search other example, most of the schematic shows just one fuse. So, I removed it. Your recommendation is totally make sense, I will update schematic with it.

     

    Thanks,

    Takashi

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    14 AWG is quite adequate. A 10 foot run of 14 AWG to the headlights would have a voltage drop of about 0.25VDC. Going up to 10 AWG gives you a drop of 0.100VDC.

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    Simplified version schematic.

     

    post-24248-0-39740300-1432848851_thumb.j

    one 30A fuse version.

     

    post-24248-0-33556300-1432848864_thumb.j

    two 10A fuse version.

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    Found good size relay box from Junkyard Toyota car.

    From my schematic, I can just modify wiring within Engine bay.

     

    post-24248-0-27119400-1432851018_thumb.j

    post-24248-0-36255600-1432851013_thumb.j

    post-24248-0-21090300-1432851024_thumb.j

     

    It fits 3 relays and 1 30A fuse.

    I can use 2 relays and 1 fuse for headlights and another relay for something else :-) Maybe radiator fan?

    Edited by tamo3

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    Before I finished up my relay upgrade, I was also looking for a pre-existing box to house the relays and some fuses.

     

    Here's the best one I could come up with.  It's a pretty adaptable relay/fuse box from (I think) the later model of Corolla. I like it because not only does it have room for four relays, but it also has four of the mini blade fuses. This is the only pic I have handy right now:

    P1040326_zpsgiawotxn.jpg

     

    I'll try to snap a couple better pics of the box with the lid.

     

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    Captain, 

    You scored good one! I saw a lots of Camry at junkyard, but not much Corolla. That's nice one!

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    You scored good one! I saw a lots of Camry at junkyard, but not much Corolla.

     

    Tamo, It's yours if you want it. I'll send it to you if you would like.

     

    I'm not going to use it now that I've got my headlight relays mounted using a different scheme.

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    Found good size relay box from Junkyard Toyota car.

    From my schematic, I can just modify wiring within Engine bay.

     

    attachicon.gifIMG_8303.jpg

     

    It fits 3 relays and 1 30A fuse.

     

    Hi Tamo,

     

    Looks like it will make a nice clean setup when you finish. Be sure to take some photos when you fit it.

     

    My headlights have been changed to meat european regulations and the PO upgraded to H4 with 60/55Watts bulbs. The original system uses 50/40Watts. I would like to do something like this to protect the combination switch now the system is using 20% more energy in high beam..

     

    I have one small issue: The system will work on just one fuse. That means if it blows you will have no lights.

    Could you double the relay bank for a left and right system. That way if a fuse should blow you will only loose the left or right (Hi and low beam) headlight. It would mean you will have two reserve relays for fog lights and fan etc.

    I do a lot of HAZOPS, RCFA and FMEA where I work and its second nature to prepare for the worst.

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    Hi Chas,

     

    I was looking at Captains 4 relays schematics.

    http://www.classiczcars.com/topic/51554-a-different-headlight-relay-upgrade-4-relays/?p=470544

     

    However, your requirement is to have 4 fuses too.

     

    So, I modify my schematics for you with just for fun:-)

    post-24248-0-80546600-1432917476_thumb.j

     

    I also replace with H4 headlight, but I'm not so much worry about safety issue since I'm not planning to drive at night...LOL!

     

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    Tamo, It's yours if you want it. I'll send it to you if you would like.

     

    I'm not going to use it now that I've got my headlight relays mounted using a different scheme.

     

    Thanks Captain for your kindness of your offer. I really appreciate it!

    Currently, I will stick with my box. I'm pretty sure other audience might want it from you :-)

     

    I just order Open Barrel Terminal Female socket on ebay.

    http://www.ebay.com/itm/140962830904?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

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