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Wiring Question (I hate electricity...)

bigred88

bigred88

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I recently rewired my headlights on my AMC Spirit. I just rewired the grounds- to a larger gauge. The headlights had been really dim, so this was my first effort to make them brighter. As a part of the rewiring, I relocated the ground to under the hood (it ran, combined with a few other components, through the firewall). I left the other components untouched- they still go through the firewall. When I finished and started the car, I burned through a fuseable link that goes from the ignition to the alternator.

I'm trying to figure out what I did, but electrical wiring is a nightmare for me- everything is really confusing. I tested to make sure that the other components (one of which is connected to the solenoid) still had a good ground, and they do. Anyone have any ideas here? Any wiring gurus out there that can point out all the mistakes in my simple wiring ideas?
 
I don't think that that word means what you think it means.....
You say you reran the "ground".
Ground is the negative terminal of the battery, and is hooked to the body, frame and engine.

The ground for a headlight is usually attached to the body, close to the headlight.
If you found a wire that ran through the firewall, that is not likely to be a ground. Remember, automotive color codes are not the same as house wiring.

You need to remove the wire you hooked up under the hood, and re-hook it where it was.

That should eliminate the short, and after you replace the fusible link with the correct size one, repost here, and we will try to talk you through upgrading the headlights the minimum smoke way.

J.
 
In the wiring diagram for the car, the wire is clearly labeled a ground, and runs through the firewall to a common ground under the dash. I don't know why (it makes more sense to me to ground it to the body close to the headlights, which is why I did that). But it is a ground wire.

And I know what ground is. I've taken college level electrical engineering classes- the stuff still confuses me, but I know what a ground is.

If you have input on how to rewire headlights a different way, I'd be glad to hear it.
 
If your lights are dim theres not 12v being sent. check for resistence in the power wire (after rewiring the fusible link you destroyed). fusible links go when theres a short.

Ide first unplug the harness and check voltage there. Good lucksky
 
Old lamps will also cause dim lights. I replaced the lamps on my Cherokee with new bulbs and that helped alot!
 
Yep, did that one. Even put in Sylvania Silverstars, which I run in my K5 and love. Didn't do much in the Spirit though, which is why I was trying to upgrade/fix the wiring.
 
Ok, first of all, we need to get the car back to its orginal condition. Take loose what you did and hook it back up the way it was.
While you do that, pay close attention to anything you might have moved, disconnected, or taken off and put back on.
Its not unusual to get a pinched wire while working on something else.
Then after you have replaced the fusible link with another, and the car is running the same way it was, then we can start looking at what is making the headlights dim.

After we get going again, we need to start with the basics.
You have replaced the bulbs, so they should be OK.
I assume that the lenses of the headlights are not yellowed by the Ultraviolet from the sun.
So, the first thing we do is measure the battery voltage at the battery with a good voltmeter with the engine running at fast idle or above.
It should be between 13.5 and 14.5 volts.
Be sure that it holds that with the headlights on brights.
If the basic voltage is good, then you need to check the voltage at the back of the bulb.
This is where the relay system comes in. Often the wiring going from the power source to the headlights is not bad, but it is small for the use.
If you are getting a significant voltage drop at the bulb then a relay kit should help.

This relay's coil is hooked to the headlight switch wire, and the contacts get hooked from directly to the battery and directly to the bulb via a short heavy guage wire, thus the bulbs get full power.

Go ahead and get the link replaced and hook everything back the way it was, and get it all charging, and write back.
We will be be able figure something then.


J.
 
No one mentioned it yet, but a short circuit is what caused the fusible link to fry. You need to find the short and remove it.
 
Putting it back to normal tomorrow. I have a voltmeter in the car, and it always measures around 13.5, but always drops to about 12.5 with the headlights on. Haven't measured it at the battery yet, since I don't have the car back together yet.

I don't quite understand the relays. Any good links to a manufacturer? I guess I'm not really seeing what they are. Time to get on google...
 
Car voltmeters are not always accurate. Usually, but not always.
If yours is accurate, then you have some kind of alternator problem. Headlights should not load it down that far.

Here is what the relays do:
When you turn on your headlights, the power comes from the battery, goes to the light switch, and then from the light switch to the headlights.

All through small wires, and connections. This can cause voltage drops that result in lower voltage to the bulbs.

With a relay, you run a heavy wire directly from the battery, through a circuit breaker to the relay.
Then another heavy wire from the relay contacts to the bulb.
Then, the wire from the switch that used to supply the bulb, now only has to turn on the relay.
Thus, you get full battery power to the bulbs.

This will help some with stock bulbs. If you put in brighter bulbs that draw more current, then you increase the voltage drop of stock wiring, and the relays help more.

If you really go overboard with the bulbs, often you will exceed the current setting of the built in circuit breaker in the switch, and they will blink off and on.
The relay system removes the load from that breaker.

J.
 
That helps a lot. I had done some research on relays, but that explains it the best. Thanks for your help on this. Wasn't able to get the car back together (work went late), but this weekend for sure.

I've always had a problem with the high beams flickering off sometimes- I always just thought it was a bad ground, or maybe the switch for the high beams, but it sounds like this might fix that too...
 
Got it back together today. No problems, no more shorting out. I still have no idea what caused that, which bothers me. In my mind, simply relocating a ground, or removing one ground wire from a group of ground wires, as long as it is properly ground elsewhere, shouldn't be a problem. But apparently it is, sometimes.

Now I'm gonna look into relays.
 
Well, now I'm having a couple of problems crop up. First, the starter is taking much longer than usual to engage. Usually it engages right away, goes real slow for a turn or two, then fires right up. Now, it's like the power is having to build up before it gets to the starter. I actually heard it doing that today- it was weird, I'm not sure how to describe it. And my stereo goes out for just a split second now and then. Every 5 or 6 songs- not often, but it never did this before.

Anyone have any ideas?
 
OK, like the old joke, we got your nose cleared up now we need to work on your ears<G>.

You have all the symptoms of a voltage problem. Could be battery, could be wires, or alternator.
Grab your voltmeter, crank the truck, and check the voltage at the battery terminals. If you have top terminals, put the probes on the lead terminals themselves, not the clamps.
You should have above 13.5 and below 15 or so. I would expect about 14.5 with just the engine on.
If so, try it with the headlights on, and then add the fan wide open.

If it drops below 13.5, and the battery is good, check your alternator belt to see if its loose. If not, then you need to get the alternator checked.

If all that shows good, then we need to start looking for voltage drops.

Turn the engine off, and turn on all the electrical loads you can. Lights, high fan, stereo, etc.
Put your voltmeter on the one or two volt scale, and measure from the positive lead battery terminal, to the positive clamp. If you see more than a couple of millivolts, you need to clean the terminal.
Do the same thing from the negative post to the negative terminal.
Then, go from the positive terminal to the post the positive wire is hooked to if you can.
Same thing on the negative side.
You are looking for a voltage drop or loss. A connection that is perfect, should not lose any voltage across it under a load.
Of course, no connection is perfect, but you should not see much loss.

If you have a wire hooked to a post, with high currant flowing through them, and you measure from the wire to the post it is hooked to, and see a couple of volts difference, then the connection is bad, and those volts are not getting to the equipment you are trying to power.

I figure you have done that before, but I wanted to explain it to anybody else reading this and wondering why I would suggest measuring from the post to the clamp when they are hooked together and should not have any voltage between them.

More than likely, you are going to find a bad connection.
If you find a voltage drop from the battery to the starter post, but the connections seem good, don't rule out a battery cable corroded inside. That is one of those little hidden problems that checking voltage drops is so good at finding.

Let us know what you find. It may turn out to be a bad starter, but lets check the easy stuff first.

J.
 
It's also possible that the short circuit that popped the fusible link also fried the battery or the alternator.
 
AAARGH!

So, the battery has 12V after sitting for 2 days, has 14.35 when running. No loss from the terminal to the clamp, no loss across the cables.

My next guess is the starter, too. It has always cranked slow a few times, then caught up and cranked fast enough to start the engine. I think the starter is coming out this weekend to be bench tested.
 
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