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Thread: Rooftop light wiring help?

  1. #1

    Default Rooftop light wiring help?

    Hey there, I've got a auxiliary light install that I'm trying to figure out and I've come here for some guidance. I purchased an IPF868cs light kit and am going to install both lights onto the roof rack of my 4runner.

    The light kit came with a wire harness but it's far too short to reach where i need it to go, I think it's suited for bumper light installations. I need to run about 9 feet of power and ground, at the farthest point, from the lights to the relay. The power and grounds on the kit harness are 16 gauge. I figure I can just replace those power and grounds with new longer lengths of 12 gauge.

    The lights have 100w bulbs in them. The issue I'm truly facing is that the headlight housings are pre-wired in 18 gauge for power to the bulb and ground to the metal housing. I was told at a local electrical parts store it'd be fine to snip the 18 gauge bullet connectors off the ends of the housing wires and splice in some 12 gauge wire and connectors. That just doesn't feel right to me... I want to wire these for safety and performance.

    My question is, can I just re wire the housing in 12 gauge? Take the 18 gauge out and replace it with 12 for power to the bulb and ground to the metal housing, throw on an appropriate connector and then run the rest in the longer 12 to the relay?

    The kit included a 20 amp relay, fused battery power wire, fused signal wire and switch.

    Here are a couple of pictures of the light housing wires.

    Thank you much in advance. I'm eager to get this project underway and get these lights up!

    Last edited by -Virgil-; 02-25-2018 at 09:29 PM.

  2. #2

  3. #3

    Default Re: Rooftop light wiring help?

    Welcome to this board. I've fixed your topic title for you.

    By your description, the wiring harness that came with the lights is not adequate to safely and efficiently run a pair of 100w bulbs especially with long wire lengths. And You're right to suspect the bad advice given by the goofball at the electrical parts store. You would want 12 or 14 wire for the entire length of the power circuit, from the battery to the relay and the relay up to the lights. Also, soldering is not the right technique for a vehicle application. There are good articles on the why-and-why-nots of it here and here.

    An easy and dependable way out of your bind would be to buy this heavy-duty Hella harness (their part number 87-199. It's got stout wiring throughout, probably long enough right out of the box, got a good quality switch, etc. You have to pay attention to how you hook it up for two reasons: your Toyota has a switched-ground headlight circuit, and you need to make sure the harness is hooked up correctly for "driving" (aux high beam) lamp operation so the roof lamps automatically switch off when you switch the main headlamps to low beam. Hella's instructions (ala German style, though you get English words) are here, and there are good notes about the switched-ground issue here.

    Also, you ought to re-think the bulbs in your lamps. 100w bulbs sound like the hot ticket, but generally they aren't. You can do much better in terms of beam focus (and resultant seeing distance and spread) with a well-chosen 55w bulb, that is this one. For background info on this, see here. That's a comparison done with H4 bulbs, not the H3 bulbs your new lamps take, but the principle holds true.

  4. #4
    Moderator Alaric Darconville's Avatar
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    Default Re: Rooftop light wiring help?

    Position and aim of these lamps will be important-- you don't want any of this light striking your hood, causing yourself glare.

  5. #5

    Default Re: Rooftop light wiring help?

    Thank you so much for the replies. And for fixing my title. So far I've gone ahead and replaced the 18 in the light housing with 12.






    I've also decided to use silicone coated fiberglass insulation throughout the new harness to protect the wiring and keep it neat. It's rated to 270F as well. The parts of the wiring kit I'm not changing include a 20A relay, a relay socket, a 3 foot length of 14 gauge to battery (25A inline fused), several feet of wire that plugs into a mouse style switch and a wire to tap into the high beam switch (2A fused inline).

    Switch with yellow to headlight and power and ground to relay.


    Relay socket with yellow from battery, power and grounds from switch. Empty space will be for power to lights. I'll ground them to the battery.


    Relay



    I've gotta find weatherproof plugs for the lights and make the rest of the power and ground for them to the relay.

    I noticed in the box that they do come with 55w bulbs also. So I may get better results from them? I'll check out all of your links and read up. Thank you!

    Quote Originally Posted by Alaric Darconville View Post
    Position and aim of these lamps will be important-- you don't want any of this light striking your hood, causing yourself glare.
    My lights are mounted this same way, just behind the sunroof, so glare shouldn't be an issue. Although I'll aim them properly anyway.
    Last edited by -Virgil-; 02-27-2018 at 01:36 PM. Reason: Remove unnecessary wholesale quote

  6. #6

    Default Re: Rooftop light wiring help?

    That "IPF" (labelled) relay needs to head on a one-way trip into the trash bin. Get a reputable-brand, standard form factor relay so you're not stuck outta luck when the "IPF" one fails. Recent discussion of relays can be found in post #21 of this thread.

    I noticed in the box that they do come with 55w bulbs also. So I may get better results from them?
    That is not what was suggested. Please re-read post #3.

  7. #7
    Moderator Alaric Darconville's Avatar
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    Default Re: Rooftop light wiring help?

    I second that both on the relay and the bulbs. There's no telling* what quality bulb you'll have that came with those lamp assemblies-- just skip straight ahead to a known high-quality bulb.

    *Actually, there is telling. It'll be a poor quality bulb with sloppy filament precision and placement.

  8. #8

    Default Re: Rooftop light wiring help?

    Quote Originally Posted by -Virgil- View Post
    That "IPF" (labelled) relay needs to head on a one-way trip into the trash bin. Get a reputable-brand, standard form factor relay so you're not stuck outta luck when the "IPF" one fails. Recent discussion of relays can be found in post #21 of this thread.



    That is not what was suggested. Please re-read post #3.
    I've gone through and read all of your links. Great info. I see what you meant now by suggesting those 55w bulbs as opposed to me just assuming the 55's in this kit would be better.
    I'll pick up a Bosch relay. I read your post in another thread you linked that said to buy a relay with two 87 terminals.

    So, I'm basically at the point where if I want this done right I should scrap the harness that came with the lights and start from scratch? I'm all in for the project. I love to learn and make things work. New relay, new power and grounds for the lights (in progress as discussed). How about a switch and signal wire for the high beams? The mouse style switch really sucks anyway. Would you recommend adding one of these into the mix https://www.amazon.com/gp/product/B0...KIKX0DER&psc=1? For later expansion to other accessories.

    Quote Originally Posted by Alaric Darconville View Post
    I second that both on the relay and the bulbs. There's no telling* what quality bulb you'll have that came with those lamp assemblies-- just skip straight ahead to a known high-quality bulb.

    *Actually, there is telling. It'll be a poor quality bulb with sloppy filament precision and placement.
    I'm sure you're right. Just generic kit parts thrown together.
    Last edited by dylans; 02-27-2018 at 04:45 PM.

  9. #9

    Default Re: Rooftop light wiring help?

    Quote Originally Posted by dylans View Post
    So, I'm basically at the point where if I want this done right I should scrap the harness that came with the lights and start from scratch?
    I would. IPF makes some good lights, but they tend to fall on their face with bulbs, harnesses, etc.

    How about a switch and signal wire for the high beams?
    Included with that Hella harness I linked above.

  10. #10

    Default Re: Rooftop light wiring help?

    Ah alright. I'll try that harness out. Hopefully it'll be long enough (~9ft). I see a relay is included, how's the quality though? Good enough to use?
    Last edited by dylans; 02-27-2018 at 05:05 PM.

  11. #11

    Default Re: Rooftop light wiring help?

    From the notes page on the HL87199 harness

    Exceptions –
    Some Japanese vehicles switch GROUND instead of power to the headlamps. If you have one of these vehicles, swap the power and ground from the harness to the battery. Everything else remains the same except do not try to run a separate ground to the lamps and insure none exists through the shell of the lamp – you must use the ground supplied by the harness. You should also FUSE the Ground with the same size fuse as is in the +12v circuit or as is on the relay. Also, you must use the switch supplied with the harness – ONLY.

    Could the lines in red be clarified?

    1. Swap the power and ground from the harness to the battery.
    2. Do not try to run a separate ground to the lamps...
    3. You should fuse the ground...

  12. #12

    Default Re: Rooftop light wiring help?

    Your 1-2-3 point list there accurately restates what's in red, so it looks like you understand it correctly. The relay is adequately good quality, and it's of a standard form factor that can easily be replaced.

  13. #13

    Default Re: Rooftop light wiring help?

    Quote Originally Posted by -Virgil- View Post
    Your 1-2-3 point list there accurately restates what's in red, so it looks like you understand it correctly. The relay is adequately good quality, and it's of a standard form factor that can easily be replaced.
    I apologize, I meant to make them questions.

    1. I'm not sure what it meant by swap the power and ground from the harness to the battery. Does it mean swap the positions on the relay?
    2. As far as a separate ground to the lamps goes. The aux lamps? They've already got their own ground.
    3. Fuse which ground?

    Again, sorry. I really know nothing about setting up lights and relays and wiring them all to work. So much of this is a foreign language to me.
    So far on my new shopping list I've got the Osram bulbs linked here and the Hella harness. I also found this one http://www.painlessperformance.com/webcat/30803.
    If either harness is truly plug and play, i.e. long enough at least, then all I should be worried about at this point is wiring everything correctly to suit the ground switched headlights.

    Thank you for your responses and patience!

  14. #14

    Default Re: Rooftop light wiring help?

    Quote Originally Posted by dylans View Post
    I apologize, I meant to make them questions.

    1. I'm not sure what it meant by swap the power and ground from the harness to the battery.
    The harness has a + wire and a - wire to connect to the battery. Usually you'd connect the + wire to the + terminal and the - wire to the - terminal. Because of how your vehicle is wired, you need to connect them the other way around.

    As far as a separate ground to the lamps goes. The aux lamps? They've already got their own ground.
    Good. The point here is make sure the lamps aren't trying to ground via their mounting hardware. Their ground wire should be the one and only ground.

    Fuse which ground?
    The one that's connected to your battery + terminal.

    (And forget that "Painless" junk.)

  15. #15

    Default Re: Rooftop light wiring help?

    Alright, as I've understood it before your clarification:

    Starting from the roof lights their power and ground will run into the engine bay.

    Their power will go into a relay. Their ground will connect to the battery's negative terminal.

    A fused power wire will run from the battery's positive to the relay.

    Because of the way my vehicle is wired though:

    I would run the roof lights power wire to the negative battery terminal? The roof lights ground into the relay, and then a fused ground wire from relay to the positive battery terminal?

    EDIT: That doesn't seem right at all. Seems like a good way to fry everything. I'm going to read more into how relays work and how ground switch systems work.
    Last edited by dylans; 02-28-2018 at 03:42 PM.

  16. #16

    Default Re: Rooftop light wiring help?

    No.

    Install the new Hella harness with the following special procedures:

    -The harness (-) wire gets a fuse installed in it, close to where it will connect to the battery.
    -The harness (-) wire gets connected to the battery (+) terminal.
    -The harness (+) wire gets connected to the battery (-) terminal.

  17. #17

    Default Re: Rooftop light wiring help?

    Quote Originally Posted by -Virgil- View Post
    No.

    Install the new Hella harness with the following special procedures:

    -The harness (-) wire gets a fuse installed in it, close to where it will connect to the battery.
    -The harness (-) wire gets connected to the battery (+) terminal.
    -The harness (+) wire gets connected to the battery (-) terminal.
    Alright, thank you. The only other modification I should need to do is add wire to the power and ground leads for the lights if they're not long enough out of the box. I assume that I'll just need to match any new wire I add to the wire gauge on the harness?
    Last edited by dylans; 02-28-2018 at 04:49 PM.

  18. #18

    Default Re: Rooftop light wiring help?

    Yup, now you're talkin'.

  19. #19

    Default Re: Rooftop light wiring help?

    I dug through the site you linked in an earlier post and found this. http://www.rallylights.com/auxiliary-lamp-wiring
    that diagram really helps, and it mentions wiring for a ground switching circuit in the note at the bottom.

    I also found this diagram specific to Toyota ground switching and adding lights. http://www.sleeoffroad.com/technical/images/lights.PDF

    This will all come together. Having the harness in front of me will help tremendously. Hands on and visual learner here...

    I've also found this link https://www.the12volt.com/relays/page1.asp
    Last edited by Alaric Darconville; 03-01-2018 at 08:05 AM. Reason: Combining posts

  20. #20

    Default Re: Rooftop light wiring help?

    I went out this morning to find which wire on the headlight plug is power and considering it's ground switched I expected to get 12 V on the multi meter when I found it. I hooked the ground lead to the negative battery post and probed the two connectors in the plug. I got no voltage in both. With the high beam switch on, I get the 12 V on the power lead for the connector and 24.3 mV on the ground for the connector. This was all unplugged from the bulb.

    Seem strange?

  21. #21
    Moderator Alaric Darconville's Avatar
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    Default Re: Rooftop light wiring help?

    Quote Originally Posted by dylans View Post
    I went out this morning to find which wire on the headlight plug is power and considering it's ground switched I expected to get 12 V on the multi meter when I found it. I hooked the ground lead to the negative battery post and probed the two connectors in the plug. I got no voltage in both. With the high beam switch on, I get the 12 V on the power lead for the connector and 24.3 mV on the ground for the connector. This was all unplugged from the bulb.
    I believe on my Previa the H4's "neutral" pole is the one that gets the power, the "hots" for each individual filament are the ones that are the ground and their path to ground is switched. So try putting the a probe on the "neutral" and on the negative battery terminal. It's also possible that your headlamp circuit is supervised and if filament resistance isn't detected, it may cut the power.

  22. #22

    Default Re: Rooftop light wiring help?

    Quote Originally Posted by Alaric Darconville View Post
    I believe on my Previa the H4's "neutral" pole is the one that gets the power, the "hots" for each individual filament are the ones that are the ground and their path to ground is switched. So try putting the a probe on the "neutral" and on the negative battery terminal. It's also possible that your headlamp circuit is supervised and if filament resistance isn't detected, it may cut the power.
    Alright, I tested as you suggested.

    With no key in the ignition it reads .1 mV at both terminals on the plug.
    With no key in the ignition and the driver door open (interior lights auto on) it reads 1.4 mV in one terminal and 1.3 mV at the other.
    With key in ignition to ACC it reads 2.6 mV on one terminal and 2.4 mV at the other.
    With key to ON it reads 4.9 mV on one terminal and 4.5 mV at the other.
    With engine started it reads 12.6 mV on one terminal and 10.9 mV at the other.

    There are two wires, one is thinner and is green with black stripe and the other is thicker and white with black stripe. The green/black wire is always higher in mV. With the driver door closed the voltages are always slightly lower.
    My initial test this morning was after the truck had sat all night. These tests were done after driving around for a while.

    Here are the first 3 pages from the FSM headlight wiring diagram section. I'll be tapping the left hand high beam.


    Last edited by dylans; 03-01-2018 at 11:18 AM.

  23. #23

    Default Re: Rooftop light wiring help?

    Today I discovered that placing the negative probe on the positive battery post and then probing the bulb connector terminals gives -12.67 V. Both terminals give the same reading.

  24. #24

    Buttrock Re: Rooftop light wiring help?

    I finished the install. The Hella harness is great! I hooked it up by swapping the power and grounds on the battery and when I hooked the battery back up the lights stayed on when the headlights were off and they went off when I turned the headlights on.

    I tapped the green and black wire on the high beam in the above diagram page 2. So I swapped the battery cables to 'normal'. Power to power ground to ground and they worked as intended. Off with lows, on with highs and cabin switch. Off with cabin switch off. They go off automatically when I switch from high to low and they come on when I flash the high (with cabin switch on).

    Great! Thanks for all of the help . I guess my Toyota isn't ground switched?

  25. #25

    Default Re: Rooftop light wiring help?

    Weirdness and model-to-model inconsistency is the hallmark of Toyota lighting wiring. Glad you got it figured out!

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