Help with yellow output from new utility lights

I just installed a set of Blazer utility lights on the rear of my Tacoma. One of the main reasons was that when I have to go and mow at my moms house after work, which by the time is all said and done it is dark when I get home, to help me see disconnecting my trailer and putting all the stuff away.

I installed one flood 3x6 behind the drivers side, and a spotlight 3x6 on the passenger side. I wound up having to install 2 seperate switches because when I would fire them both up at the same time they would look plum yellow. I hate yellow, looked like the battery was dead.

I don't know why this was, I used 12ga. wire thru out. They were very well grounded, and I used a switch rated at over 30 amps. I figured they are pulling about 4.5 amps each. If anyone knows why this was please tell me! I am planning on asking for driving lights for Christmas and do not want to have to install 2 swithes again. I have the hot wire connected to a hot fuse under the dash board, one for each.

But when I gave them there indvidual wire paths to seperate switches they are nice and white. Which is acutally pretty cool, now I can turn the truck off and use just the flood one to see what I am doing and it is not as hard on the battery.

Turn the lights on and measure the voltage at the power connection, then measure the voltage at the lights. Keep in mind that even a 1.2v drop is still 10% in a 12v system, and that a 10% voltage loss will reduce the output of a halogen bulb by nearly half, not just 10%.

What I would do:

Go to 10 awg wire; front of your truck to the rear is a pretty long distance @ 12v. Pull power directly from your battery with a fuse. Don't run the power directly through your switch, that's just more distance the power has to travel. Use a relay right next to the battery instead. Lastly, don't rely on the frame or bumper or whatever being a good ground. Run a separate ground wire straight back to the battery; make sure it's the same size as the positive wire. Solder, don't crimp, and don't even think about Scotch-locks.

:buddies:

Thanks for the replies guys. Bomber, after having all the trouble that I did, that is the way I wish I would have went about it. It would have made wiring the rocker switch alot easier too.

What's going on with these threads? Has a moderator done some spring cleaning/rearranging?

Edit: Ah, found it. Your original post wasn't in the thread I thought it was. It's all still there.

Diesel_Bomber said:

Run a separate ground wire straight back to the battery; make sure it's the same size as the positive wire.

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If you run a dedicated ground wire directly to the battery, this wire will also need a fuse. If the main ground path becomes compromised (e.g. OE ground strap becoming corroded or falling off), the new ground path to battery will be through your lights and light wiring. And I'm sure you don't want a few hundred amps flowing through a 10 gauge wire when you start the engine. ;-)

scott.cr said:

If you run a dedicated ground wire directly to the battery, this wire will also need a fuse. If the main ground path becomes compromised (e.g. OE ground strap becoming corroded or falling off), the new ground path to battery will be through your lights and light wiring. And I'm sure you don't want a few hundred amps flowing through a 10 gauge wire when you start the engine. ;-)

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Thanks for catching that! I've seen a speedometer drive cable vaporized by this same phenomenon.

:buddies:

scott.cr said:

If the main ground path becomes compromised (e.g. OE ground strap becoming corroded or falling off), the new ground path to battery will be through your lights and light wiring.

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How? :thinking:

For the starter motor to want to ground through the lights, the positive side of the lights would have to be shorted to ground, ie the negative side of the starter motor. I suppose it could happen, but that's in addition to the main ground falling off, and there wouldn't be hundreds of amps flowing, just a maximum of what the bulbs normally let through with the full 12V, which of course they cope with just fine.

For you to get hundreds of amps you'd have to short out the fuse in the positive wire.

This extra ground wire would presumeably only be run in exception situations where a good ground couldn't be obtained with any sort of ease at the lights, since it would add extra resistance for the lighting circuit. I'm assuming a partial ground wouldn't be made (and maintained) at the lights.

great stuff guys. But would'nt the in line fuse just pop if something were to happen to the ground wire and it shorts?

Torch Boy, yea you got it right.

hburner said:

But would'nt the in line fuse just pop if something were to happen to the ground wire and it shorts?

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Now, which in-line fuse? And shorting to what?

You know, I've never put a fuse in a ground wire because they're all at zero potential, all on the ground side of devices like driving lights or starter motors which (should) have the 12V voltage drop across them. I've kept them all as short as possible too. It's the positive side that needs protection, so every wire I've added to the positive battery terminal (air horns, lights, etc) had an in-line fuse right there, close enough so the wires wouldn't have a chance to wear or melt through without being protected by the fuse.

Unless something really goes wrong I don't think you should need more protection, but it's fun trying to second guess what could go wrong.

TorchBoy said:

How?

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A standard OE ground path is solely a wire braid from the battery negative to chassis (or in the case of body-on-frame vehicles, from battery to frame and battery to body).

This means that if you have things wired directly to the battery negative, they stand a chance of becoming the new ground path should the usual ground strap fail.

(Assuming a standard negative-ground system of course.)

[]Now, which in-line fuse?I was referring to the postive in line fuse.And shorting to what?that would be if something where to go wrong anywhere along the wire paths, ex. squashed pos wire to bare metal.

Now I see what he was saying about the ground needing a fuse also. That would probably never happen, but then again in my case it probably would. thanks, hb.

thanks for all the inpu and different view, I learned something here, as usual on CPF.


You know, I've never put a fuse in a ground wire because they're all at zero potential, all on the ground side of devices like driving lights or starter motors which (should) have the 12V voltage drop across them. I've kept them all as short as possible too. It's the positive side that needs protection, so every wire I've added to the positive battery terminal (air horns, lights, etc) had an in-line fuse right there, close enough so the wires wouldn't have a chance to wear or melt through without being protected by the fuse.

Unless something really goes wrong I don't think you should need more protection, but it's fun trying to second guess what could go wrong.[/quote]

scott.cr said:

A standard OE ground path is solely a wire braid from the battery negative to chassis (or in the case of body-on-frame vehicles, from battery to frame and battery to body).

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Yeah, got that bit OK.

scott.cr said:

This means that if you have things wired directly to the battery negative, they stand a chance of becoming the new ground path should the usual ground strap fail.

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That was the bit I was wondering about. I tried to figure out what combination of very rare events would lead to that. Not only would the main ground link have to come off the battery, but then, not before, something else would have to contact where it wasn't supposed to as well - for example, a direct unfused positive to negative contact. If that happened it wouldn't really matter if the main ground braid was on or off - you'd have trouble.

Like I mentioned earlier, I'm assuming there wouldn't be even a partial ground at the lights end of the ground wire. if you're going to run the ground wire to the battery instead of the nearest good spot on the chassis, make sure the lights themselves are not grounding. That may be really hard to do, depending on the design of the lights. Maybe the difficulty of doing that is why ground wires aren't normally run to the battery.

Hmmm... Yeah. Don't do it. Or use an in-line fuse like Scott said.

Many lights ground through their casing. In some cases this is the ONLY ground, and often not adequate. Even if this isn't intended to be the only ground, there is often times still a ground path. This additional ground point is the reason Scott.cr suggested fusing the dedicated ground wire, and the reason I agree with that practice.

Often times the nearest chassis ground is suspect. There may be a solid connection where you connect your wire, but then the power might have to go through umpteen rusty bumper or body mounting bolts and other corroded wires to reach a decent ground(Think you're OK because your car is new? I've seen wires corroded clean off of 2 year old cars.). All cause voltage drop, hence the reason I recommended a separate ground wire. The speedometer cable I saw get vaporized happened when some idiot cranked their truck over and forgot to hook the ground cable to the engine block, leaving only the body ground in place.

All this said, I haven't fused any of the dedicated ground wires on my vehicles. These are my personal vehicles and I'm the only one that works on them. I've rebuilt and redesigned large parts of their electrical systems and I'm confident that there will always be a solid engine ground.

To sum it all up: If you're worried about it, run the dedicated ground wire to the engine block instead of the battery.

:buddies:

Diesel_Bomber said:

Often times the nearest chassis ground is suspect. There may be a solid connection where you connect your wire, but then the power might have to go through umpteen rusty bumper or body mounting bolts and other corroded wires to reach a decent ground

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I wouldn't call that the chassis. I would recommend grounding to chassis, not to a metal bumper, door, etc.

Diesel_Bomber said:

To sum it all up: If you're worried about it, run the dedicated ground wire to the engine block instead of the battery.

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Sounds good.

I think when I go to put driving lights I will wire it straight to the battery, pos and neg. And I will put an in line fuse on both, no big deal to do it. It is just so close to the battery I figured what the heck?

Now I just need to figure out which lights to get (Christmas money)