H4 Tom's Headlight Replacement Help

[dedgar]

So I got the H4 headlights and wire harness from Tom's Bronco and installed it tonight. Pretty straight forward but, for some reason only the driver light turns on, then after a full pulls on the light handle, the passenger turned on. Then when I do the brights, only the drivers works and it looks like the passenger is way dimmer than the driver.

any thoughts on this?

 

[DirtDonk]

Yeah, that's not right. Did your lights work OK before? Or at least they were the same brightness left and right?

First thing I would check would be the ground wires. The new 3-wire connectors have their own new grounds, correct? If they're connected then pull them off of the core support and clean the area underneath real good (unless you did this prior to the installation?). Put them back on good and tight.
With the relays getting more potential current to the lights, your grounds need to be first rate.

And speaking of that, does your main battery ground have a jumper to the body?
The main cable goes to the engine of course, but you need to have one to the body as well. Usually the inner wheel well is where the factory had it.
Try this trick to see if it helps the lights. Connect a temporary jumper wire from the battery negative to the core support at one of the headlight grounds.
If things work better after that, your core support is not grounded to the surrounding metal well enough. Seen it happen many times.
Between paint and rust, even the spot welds no longer conduct like they did when new.

As we found the other day with someone else's headlight harness, give the relays a good smack to make sure they're not stuck.
His were older I believe, so that was not out of line. But since yours is new this would be unusual for them to stick. But it's not unheard of either, so best to check at least.

Let us know what, if any changes messing around with it does.
Sorry you're going through this with a new part, but it should be a relatively easy fix.

Paul

 

[dedgar]

Yeah, that's not right. Did your lights work OK before? Or at least they were the same brightness left and right?

First thing I would check would be the ground wires. The new 3-wire connectors have their own new grounds, correct? If they're connected then pull them off of the core support and clean the area underneath real good (unless you did this prior to the installation?). Put them back on good and tight.
With the relays getting more potential current to the lights, your grounds need to be first rate.

And speaking of that, does your main battery ground have a jumper to the body?
The main cable goes to the engine of course, but you need to have one to the body as well. Usually the inner wheel well is where the factory had it.
Try this trick to see if it helps the lights. Connect a temporary jumper wire from the battery negative to the core support at one of the headlight grounds.
If things work better after that, your core support is not grounded to the surrounding metal well enough. Seen it happen many times.
Between paint and rust, even the spot welds no longer conduct like they did when new.

As we found the other day with someone else's headlight harness, give the relays a good smack to make sure they're not stuck.
His were older I believe, so that was not out of line. But since yours is new this would be unusual for them to stick. But it's not unheard of either, so best to check at least.

Let us know what, if any changes messing around with it does.
Sorry you're going through this with a new part, but it should be a relatively easy fix.

Paul

thanks! I'll give this a try tomorrow.

 

[dedgar]

well looks like I've solved the issue. It was power. My leads were on the post but not tightened down tight enough to it. They made contact, but I guess they have to really be connected tight. Both lights seem to work and I'll give them a test tonight.

 

[dedgar]

Okay. another issue with these is I have to pull the light switch on 3 times till they light up on first start. But if I push on the brights, they work? Then they go out for a few seconds and then come back on? Plus the passenger light is way brighter than the driver? And they're not even close to my old brightness of my original stock lamps? And it's blueish and not white at all? I'm thinking these are a mistake. Anyone know why I'm having so much trouble with these? Oh, and my old stock lamps had no issues so it's not an existing problem that I had before.

 

[Slowleak]

Swap the bulbs and see if the passenger side is still brighter. If it is I suspect that you have a faulty bulb. You also might give Tom’s a call. They may have some known problems. I have the same kit installed and have had no issues.

 

[gr8scott]

What Slowleak said. You could also swap back in the old bulbs and see if the problem goes away. If not, you may have a
problem with the harness. I'm sure you watched their video?
[YOUTUBE]MoNlhgxV36s[/YOUTUBE]

 

[DirtDonk]

Very unusual problems for sure. Well, the multiple-pulls is at least. The one-side-dimmer is pretty common.
Like said, swap bulbs just to make sure, but if your dim bulb stays on the same side then you have a wiring issue. This issue could take the form of a bad wire or connection, OR a bad grounding scheme.
And yes, this might only be showing up now due to the higher amp draw of the new lights and the higher current capability of the new wiring. The old ones may just not have been taxing a ground but now they are.
The dim side doesn't happen to be the driver's side, does it?

Because you found your earlier issue so quickly, did you ever get the chance to run an additional ground "jumper" wire between the battery and the ground screws for the headlights? If you do this and your lights get brighter then you need to add a jumper wire between the core support and the rest of the body. It's likely that, in their old age, the spot welds are no longer sufficient.

For the whiter-vs-yellower issue, check the part numbers and brand names printed on the bases of the bulbs. If they're not identical then you need to get them swapped out.
If they are identical but even after fixing any wiring issues are still two different light colors, they may just be defective and need swapping out anyway. I have not seen that particular issue before, but I bet it can happen.

And speaking of body grounds, did you verify that you have at least a 10ga wire running from the negative side of the battery to the body somewhere? You have to have one of those.
As the old original cables age and fail, they get replaced with modern universal ones that often do not include a body ground connection. If yours is one of those, you can easily add your own and help with a lot of future problem elimination.

The not always coming on thing could be something with the new harness, but very unlikely to be the lights themselves I would not think. But with the other problems you just never know.
However, I would suspect the main headlight switch on that score.

Good luck.

Paul

 

[dedgar]

Thanks for all the help. I'm not a skilled wiring guy and don't own any voltage measuring devices. I think I'll just take it to someone that knows the bronco and it's wiring issues. I removed the harness and hooked up my old stock lights. Everything works fine now. At least I can drive at night again.

 

[DirtDonk]

If your Bronco is still sporting it's original wiring (and the same holds true for any older vehicle a actually) then this may be the time to become more educated at electrical stuff.
You don't need to become an expert though, so it's not going to take a big investment in tools or time in acquiring the knowledge. Just the basics to get you through what will almost certainly be more situations like this.
It's just the nature of older beasts. The phrases "wiring sucks" and "electrical gremlins" aren't just catch-phrases!;D

So a $5.00 (or free with the right coupon) volt/ohm meter or a nicer $10 buck Sears one (a nice one in fact, on sale now!) are well worth the price of admission and can do more than just a test light.

No problem taking the lighting issue to your nearest expert. Just more in the way of a warning of what to expect with these old rigs.
Comes in real handy when your alternator stops working too!%)

Good luck.

Paul

 

[dedgar]

If your Bronco is still sporting it's original wiring (and the same holds true for any older vehicle a actually) then this may be the time to become more educated at electrical stuff.
You don't need to become an expert though, so it's not going to take a big investment in tools or time in acquiring the knowledge. Just the basics to get you through what will almost certainly be more situations like this.
It's just the nature of older beasts. The phrases "wiring sucks" and "electrical gremlins" aren't just catch-phrases!;D

So a $5.00 (or free with the right coupon) volt/ohm meter or a nicer $10 buck Sears one (a nice one in fact, on sale now!) are well worth the price of admission and can do more than just a test light.

No problem taking the lighting issue to your nearest expert. Just more in the way of a warning of what to expect with these old rigs.
Comes in real handy when your alternator stops working too!%)

Good luck.

Paul

thanks Paul,

Yes I know I need to acquire the wiring skills. My wiring is original and from 1970 so it's going to go some time I know. Are there good videos on how to use all the electrical tools for cars? I can wire a house without any issues but cars are another beast.

 

[DirtDonk]

You're well on the path then. If you can wire household current you have the basic "skill mentality" and the ability to learn the new terminology and bits and pieces needed.
In other words, twist-on wire nuts are verboten!

Haha! The problem is wire nuts really do work well even in automotive environments. But they're not a perfect long-term solution, so they're frowned upon except in emergencies-to-be-fixed-later situations.
Crimping, soldering, stripping, different types of more desirable and less desirable options and wire sizes are all automotive specialized knowledge. But easy to pick up the mechanics of.
The tools are less sophisticated in auto sometimes, and you have to interpret readings rather than just having a light that says go or no-go. But it's still simple enough to learn.

The whole thing about wire sizing, when to use a relay or not (or even just what the heck a relay does!), or how the charging circuit relates to reality on a Bronco are all acquired skills. But eventually the light bulb comes on brightly!

Anyway, just by way of saying don't let it intimidate you. Just take a few more steps in sometimes before crying uncle and letting a pro do it. Sometimes it works out to be a real simple solution.

A basic assumption with our vintage Ford setups is that, while the battery might be called a "12 volt" battery, it should have more like 12.6v when fully charged. And when the engine is running and the alternator functioning properly, you will read between 14 and 14.8v in a normal setup.
Checking voltage at the battery first so you know what you're looking for elsewhere will also give you a heads-up to any voltage loss issues if you, for example, read 12.4v at the battery but only 11.3 volts at the headlight socket. Or even zero volts maybe!
A voltage loss here is just like in a house. It's either the wire is too small, too long (or both) or more likely there is a defect at a connection. Or on 50 year old wiring, even a bare wire with corrosion that's reducing it's ability to conduct.

All of that can be found by just using the two leads from a handheld volt/ohm meter. Takes about two minutes of familiarizing yourself with the tool, and about two more minutes of checking the wires.

See? Piece of cake already!%)

Paul