Both headlights burned out tonight... Why?

[Green Monster]

I just checked the voltage on my battery. I have 13.15V and it will take 3 amps. I worried about overcharging. If my battery read 13.15V and is still taking 3 amps is that a sign of a bad battery? The top of the battery looks a bit moist around the positive post.

[jrb71c20]

Originally Posted by Green Monster

I'm just curious why my battery was drained. Yes it is a about 4 years old, but typically they die slowly, not just overnight... right?

When I mentioned that I replaced the dimmer switch and external volt reg....I had replaced my 2nd new battery just a couple days before my blow out...I guess the regulator had been toasting them too, wouldn't hold a charge.....Same thing for you maybe?

[jhow66]

Here is a quick way to see if you have a drain on battery.
1--remove ground cable
2--hook test light between cable and ground
3--if light glows you have a drain
3--pull one fuse at a time until light goes out
4--when it goes out , that is the circuit your drain is on
5--if it does not go out after tesing each fuse remove , remove the plug on voltage regulator
6--if it goes out replace regulator
7--if it stays on remove all wires from alt.
8--if it goes out replace or repair alt.
9--That should help narrow it down as the wire that runs back to battery juction post is ok because it is not blowing your fuseable link.
10--(above advice carries no warrenty or guarantee)

[old man jimmy]

Taking 3 amps. is normal. It will never drop down to 0. But if you have 13 volts, go ahead & remove the charger, let it set overnight & see if you still have 13 volts. You will get vapor out the top vents, so don't worry about the top of it being moist. Just wipe it off with a paper towel, But beware, it is acid. There's no special way that batteries drop dead. Usually they go out kinda slow, but unnoticed. So could have been on the downward slide for awhile. But if it holds 13 volts overnight, I'd give it another try before replacing it. Just carry jumpers in case. jhow has good advise. I'm trying to keep it simple. I really think you're making more out of it than it is. If it were mine. I'd simply drop in a new voltage regulator, and couple headlights and call it a day. If I noticed the starter turning slow, especiely after a warm start Like after you shut down & restart about 1 hour later, I'd replace the battery. It's that simple. That's what I would do if mine did what yours had done. But it's your truck so do what you feel comfy with. If it has anymore problems after doing that, we'll take it from there. But have to start somewhere. Their's lots of good people on here who's willing to help you out.

[Green Monster]

Thanks guys. I'm have been swamped with work this week. I just have not had time to work on it yet. I'm just trying to collect enough information to get the job done correctly and quickly when I can find time to work on it Friday afternoon or this weekend. I will let you know how I make out.

That step by step list is fantastic. Thanks Jhow66!

BTW- I want to make sure I do this right. I really would hate to lose this Blazer in a CAR-B-Q blaze.

[Yukon Jack]

Originally Posted by Green Monster

BTW- I want to make sure I do this right. I really would hate to lose this Blazer in a CAR-B-Q blaze.

Can't blame you at all - that is one sweet K5. Ever consider putting it on E-bay

Seriously, while you are taking care of this problem it sure wouldn't hurt to have your shop fire extinquisher (which we all have I hope) handy and I would also consider keeping the positive battery cable loose enough that you can yank it off if you run into a problem.

Back before I tore my K20 apart I was tracking down an electrical problem and I watched one of the engine bay harness go up in smoke from the battery to the alternator - happened so fast I couldn't even think what to do. I was just lucky nothing started flaming.

[Musclerodz]

A drained battery is another symptom of a bad regulator. The regulator is shorted internally drawing power off the battery. I would definitely install relays on your headlights before I put those lights back in it.

Mike

[Green Monster]

Originally Posted by Musclerodz

A drained battery is another symptom of a bad regulator. The regulator is shorted internally drawing power off the battery. I would definitely install relays on your headlights before I put those lights back in it.

Mike

How would the relays for headlights be set up?

[jaros44sr]

VinceY just wrote up a good thread pertaining to that very topic, 1 page back... J.

[69TowRig]

The relay mod is great IMO but it would not have saved your headlights anyway with a regulator failure. The entire electrical system voltage went up and it still would have toasted the headlights. If anything the factory wiring would have served to help save them since the resistance is so much greater going through the entire wiring harness as OEM and the voltage drop across that would have lessened the voltage getting to the bulbs. Switching to the relay mod would have served to deliver nearly 100% full charging voltage from the alternator straight to the headlights.

[Green Monster]

Originally Posted by jhow66

Here is a quick way to see if you have a drain on battery.
1--remove ground cable
2--hook test light between cable and ground
3--if light glows you have a drain
3--pull one fuse at a time until light goes out
4--when it goes out , that is the circuit your drain is on
5--if it does not go out after tesing each fuse remove , remove the plug on voltage regulator
6--if it goes out replace regulator
7--if it stays on remove all wires from alt.
8--if it goes out replace or repair alt.
9--That should help narrow it down as the wire that runs back to battery juction post is ok because it is not blowing your fuseable link.
10--(above advice carries no warrenty or guarantee)

I finally found some time to perform some testing. I found that I have 12.15V being drawn from my ground cable.

1. I pulled every fuse, one at a time.
I had a draw of 12.15V every time.

2. I disconnected all the wires at my fuse block.
Still 12.15V being drawn from the ground wire of the battery.

3. I unplugged my voltage regulator.
Still 12.15V being drawn from the ground wire of the battery.


4. I disconnected all wires from my alternator.
Still 12.15V being drawn from the ground wire of the battery.
.

5. I unplugged my dimmer switch.
Still 12.15V being drawn from the ground wire of the battery.


I have run out of time this morning. What should I do next when time permits further investigation?

[jhow66]

Boy you are trying to make things hard! You are using your meter between ground post and ground cable-right? I need to know if you are checking it right before I go further because if you had a 12.5 drain without blowing a fuse, you would have a fried wiring harness.

[old man jimmy]

I give up...

[Green Monster]

Originally Posted by jhow66

Boy you are trying to make things hard! You are using your meter between ground post and ground cable-right? I need to know if you are checking it right before I go further because if you had a 12.5 drain without blowing a fuse, you would have a fried wiring harness.

Do I have to take pictures? Something is draining my battery when I have it connected.

I know some harness should be fried... that's why the battery has been disconnected.

[jhow66]

Are you checking it this way?

[Green Monster]

Yes. That is how I'm testing. Is that right or wrong?

[Green Monster]

I connected my battery cables. I then tested each fuse to see if I had any current passing through them. No current passed through the fuses. I pulled my hazard switch and tested that fuse. I got 11V.

I saw my under dash lights were lit so I figured I must previously tested for current on the ground cable with the door open. So I made sure I closed the door and the key was off (it has been off throughout this entire trouble shooting process). I disconnected the ground cable and bridged the ground cable to the battery with my meter. Still pulling 12V. This is maddening.

Could the memory from my radio pull 12V? That is the only thing that should be pulling any electricity.

[Green Monster]

Could my ignition switch be bad? Is there any reason my gas gauge should be reading an inch and a half past full now? It worked perfectly before this electrical issue. Any help beyond this point would be appreciated.

[Green Monster]

Just to be sure... I disconnected my voltage regulator and alternator while the doors were shut. Nothing should pull electricity except my radio. I'm still having a draw of 12V.


Could someone please test this theory? Is a 12V draw from the negative post to the ground cable normal?

[jaros44sr]

Maybe you melted a wire inside your harness before the lights blew, but I think the fusible link would have melted first. Electrical problems are second on my hate list, rust is first

[Green Monster]

Looks like I have to call a flatbed and have it towed to a automotive electric shop to get this thing fixed.

[gringoloco]

Test for amperage draw, not voltage. Everything will be 12V. Disconnect the stereo and try again. You have the fundamentals down- you just need to spend a little more time with it.

[jhow66]

That's the way to check it. Get the battery to full charge like someone else said and remove cables overnight. If it is down the next morning, you have a cell in the battery shorting out . Try another battery before going further as a short in the battery will cause a voltage spike that could cause your headlights to blow.

[Green Monster]

Originally Posted by jhow66

That's the way to check it. Get the battery to full charge like someone else said and remove cables overnight. If it is down the next morning, you have a cell in the battery shorting out . Try another battery before going further as a short in the battery will cause a voltage spike that could cause your headlights to blow.

The battery has retained a charge over several nights since I charged it. I have had the cables disconnected to prevent a disaster. The battery seems to be good.

[Green Monster]

Originally Posted by gringoloco

Test for amperage draw, not voltage. Everything will be 12V. Disconnect the stereo and try again. You have the fundamentals down- you just need to spend a little more time with it.

I attempted to check for amperage draw yesterday. I was thinking the same thing. The meter was not showing anything. I'm not too sure why it was not registering a reading. I'll try again this afternoon.