Dumb Electrical Question

Post by **ARCHINSTL** » Wed Dec 06, 2006 1:07 pm

OK -
I am still amazed by electricity; keep this in mind...
I want to add a below-the-bumper light to augment the "beam" of our single backup lamp; it simply does not do enough for my maturing eyes.
Has anyone done this, and where did you make the connection? I did a similar installation on my Dodge/Mitsu pickup, but just wired it into/with an existing backup light circuit - the OE lights are integrated into the whole taillight assembly..
Is a relay needed (not that I know what a relay is, though...)?
I dunno the strength of the bulb, but it is an inexpensive "tractor" rectangular auxiliary light from Autozone; nothing was on the package as to watts.
Thanks, and I apologize for my naivete.
Tom M.

Jts · Post by **Jts** » Wed Dec 06, 2006 2:24 pm

well, the way i see it, theres 3 ways to go about it

1) wire the lights directly into the stock wiring. This means you will be drawing more amps that originally planned. However, since you wont use it alot and the wiring is fairly beefy, you should be able to get away with it. What you would do is wire the new lights into the existing wiring, in parallel. Positive to positive, negative to negative. Mount the lights whereever you want. A new higher amp fuse might be necessary, but i feel this is fairly safe

2) wire new lights with a relay (which just connects power to whatever u want when its told to) that is driven off the stock wiring. This means u shift into rev, the stock wiring tells the new lights to light

3) wiring up new wiring completely, with a switch inside the cab to turn the lights on as you please. This is simple, but ugly and not very neat/integrated. However, if u want to use the lights while parked and engine off, this is a good idea.

Take your pick and we can go from there.

Post by **ARCHINSTL** » Thu Dec 07, 2006 12:32 am

Thanks for the answers.
I think solution #1 might be iffy and possibly less desirable for a clueless person like me.
Likewise, solution #3 seems not integrated into the automatic system.

So - it would seem #2 is the best, as it would operate just as the current system does.
I guess I should find out whether the Autozone light comes with a relay and the # of amps it draws?
I presume the connection is made in one of the rear pillars which carries the OE lighting wire(s)?

I apologize again for my obtuseness and ignorance, but while many things are not beyond my abilities, things electrical always have been, whether automotive or household.
Thanks for your help and guidance.
Tom M.

Jts · Post by **Jts** » Thu Dec 07, 2006 12:54 am

No need to appologize. My electronics skills are not the best, I took a few EE classes but i'm a mechanical. A relay will have 4 wires. 2 of them are signal wires and 2 of them are output wires. The output wires would be your hot power source. One would go to the battery and the other to the positive terminal of the lights. The input wires are the ones that switch the relay on and off.

http://www.classictruckshop.com/clubs/e ... glites.htm

This site shows a very good schematic to copy. Get a 4 pin relay. The 1st input will be you tapping into the stock back up light wiring. The 2nd input will be a wire going to chassis ground. The 1st output will be 12 volts coming from the battery(make sure you use a fuse as close as you get to the battery terminal itself, perhaps 10 amps. Depends on your light output specs) The 2nd out will go the power the new lights. Sorry if the input/output terms are confusing. Either way you have 4 wires, 1 ground, 1 that taps into the stock harness, 1 that taps into the battery, and 1 that connects the hot 12v to your lights.

Hope this helps. They sell relays everywhere, bosch is the accepted manu. of em. They run about 3-8 bucks. Hardest part about this project really is chosing the lights and mounting them. Good luck

Typrus · Post by **Typrus** » Thu Dec 07, 2006 7:45 pm

Actually a relay can have anywhere from 3 to 5 spades as I've seen. Just depends on make/application. I'd agree on 4 for generic stuff though.

I'd definitly go relay if I was you. Find the ampere draw (Amps) of the light itself. Make sure the relay matches more or less. You'll want to assure your wires are thick enough to avoid "letting the smoke out". In other words burning the wires up. Depends on the length of the wiring and the draw. There are online charts for that sort of thing.

Gasoline Fumes · Post by **Gasoline Fumes** » Thu Dec 07, 2006 9:09 pm

I wouldn't worry about the amp draw if you're using a relay. Pretty much any standard automotive relay will handle one "tractor" light. The wires do run up one of the rear pillars, but I don't remember which one. I think there should be a plug for the taillight harness behind one of the lower hatch panels. Just find the wire that has 12 volts with the trans in reverse using a meter or test light.

keith · Post by **keith** » Sat Dec 09, 2006 9:50 am

The simplest way to do this with a relay would be to put a tap in the hot wire to the current back up lamp and use that wire to power the relay coil. It should not add much load to the circuit.

Then run a new wire under the car, use plenty of zip ties so it doesn't hang down. This wire will go to one of the switch contacts, the other goes to the light. This wire should have an inline fuse as close to the battery as possible and can be attached directly to the battery terminal using a crimp on loop terminal or to the main relay in the relay box next to the battery.

With this set up, you could use two small fog/running lamps mounted under the rear bumper, similar to the way they would mount under the front bumper.

Mac · Post by **Mac** » Sat Dec 09, 2006 7:26 pm

mabey a super bright back up light would do the trick? i'd try it first before all the hastle/money of a tractor light first.

MootsMan · Post by **MootsMan** » Sat Dec 09, 2006 10:53 pm

Arch, you've given my starving mind much needed food for thought with this one.....I'm envisioning a high-mounted clear light ( mounted on top of the hatch, above the rear window, maybe ?? ), much like the lights on the back of pick-up truck cabs, bright as the sun in Death Valley at high noon, controllable from the driver's position, which could be turned on for those hard to see places you're backing into...and could also be used on the freeway when the H.I.D.-lit crowd in their expensive Japanese and German imports fly up behind me ( while I'm doing the speed limit, mind you ) and ride my bumper as I'm trying to move around a semi on the freeway. Think that would leave me open for possible arrest or lawsuit ??

takza · Post by **takza** » Sun Dec 10, 2006 3:35 am

Yea...you'll have some cop come up to ride your bumper for the fun of it...give him the light treatment...get to see the bubblegum machine work. Fun for all.

What you really need is my BRAND NEW soon to be patented FINGER GIVER. Push a button on your dash and a hand flips up in the rear window...with an extended middle finger. These can be decorated with lights for the holidays. Some will even play Christmas music.

keith · Post by **keith** » Sun Dec 10, 2006 8:44 am

Mootsman, that crossed my mind too, but I was afraid of a lawsuit for even suggesting it. I have found a position for the inside rear view mirror that tends to back them off though. I don't think they can sue for that, its their lights. I have also found that that is a good time to wash my windshield on occasion.

Normally I'm not bothered by tailgaters unless their lights are affecting my vision.

Post by **ARCHINSTL** » Sun Dec 10, 2006 9:03 am

One of the neat things about my '83 was that with drivers as mentioned above, I would squirt the rear washer and a stream trickled down the window without using the wiper; they got the message...I have continued the tradition, although with more prudence than in my youth - no road rage back then.
Hmmm - wonder if anyone makes yellow windshield fluid? ? ? ?

Someone on the TN site mentioned about striving to invent a drop-down hatch mirror that would reflect the high beams into the offender's face; wonder if that is legal ? ? ?
Tom M.

Typrus · Post by **Typrus** » Sun Dec 10, 2006 1:31 pm

I dunno how they could sue for hitting them in the face with a high-beam when they are causing YOU damage. Sue them! They are injuring you! And you can't seem to get away. One position=rear-view mirror. Another=side mirror. Another= other side. Move again? All 3 are killing you. Why not give them a taste? It hurts! Make them hurt right back!
There have literally been times I'll come away squinting with white spots in my vision because some jackass in his Beamer decided it'd be cool to tailgate me with the high-beams on his HID... I'm half-tempted to rig up a small explosion. Oh! I know! Set up a propane-fueled flame-thrower in the exhaust that'll shoot 10 or so feet. If they get to close, blast their front bumper! Lol... Oh the things to get them away...

Post by **ARCHINSTL** » Sun Dec 10, 2006 4:28 pm

Yano - it does seem that this most occurs with drivers of the BMW SportsActionVehicles, (as the genre is now termed - guess SportsCrossoverVehicle was too wussy?), and the Acura and etc. brand wagons. Wonder if they do it to 'Burbs and the like?
I do like the flamethrower option, though...

Tom M.

Mickey_D · Post by **Mickey_D** » Mon Dec 11, 2006 3:23 am

Sorry about just seeing this post. If I get time before work in the morning I'll go out to my car and I'll be able to tell you what side the wiring harness goes up and what wire it is (my tailgate no longer has the plastic door card on it, so it's REALLY easy for me to see).

I'll also be able to tell you where the plug is so you can join in on it. I'll also be able to tell you the gauge of wire and the fuse value on the existing circuit so I can tell you if wiring in direct or needing a relay is required.

Just gimme a day or two to sort it out. I've got a lot going on in the next 24 hours, so I might not get back to you right away. The joys of living in a frozen wasteland when your furnace takes a crap on you, the blower fan for the heater in the Terc quit, and I've got to try and get some answers about health benefits at both my workplace and the wife's!!

Anyways, enough of my problems. I'll get that info for you as soon as I can.