Headlights pop fuse at battery Options

[dadaDaveed]

I finally put a battery in my 914 LS1 conversion today. Nothing blew up, nothing caught fire... a good start I think. I have the JWest fuse panel and as a precaution, I also installed a small fuse block at the battery.

Here's my dilemma. I can turn on the parking lights, but turning on the headlights immediately pops a fuse at the battery (I've gone as high as a 30 amp fuse). None of the fuses in the JWest panel have blown.

I checked the fuse panel, headlight switch, and headlight relay. All seem to be wired correctly with no visible shorts.

I currently have H4 headlights installed… for the time being the wiring is stock. A friend suggested the H4's are drawing too much current, so I tried again with the bulbs unplugged… same result.

I'm stumped. Where do I look next?

[Cap'n Krusty]

The light switch seems like the logical place to start.

The Cap'n

[Mike Bellis]

Most likely the terminal on the fuse panel is shorted to ground. Unbolt the fuse panel under the dash, let it hang and try again.

[dadaDaveed]

The light switch seems like the logical place to start.

The Cap'n

What's best way to test the switch? Mine car has an early 10 post switch. I discovered my only spare is a late 11 post (IMG:style_emoticons/default/sad.gif)

[dadaDaveed]

Most likely the terminal on the fuse panel is shorted to ground. Unbolt the fuse panel under the dash, let it hang and try again.

I thought that too... the fuse panel is the first place I went. It's been hanging the whole time and I get the same result.

[Tom]

I hope you have a good print to follow. I will post a pic of what I have.
You have a short after the headlight switch. The power comes thru the key switch to terminal 15 of the headlight switch (E1). First notch of the headlight switch does not energize the headlights, second notch does. Second notch feeds power to the headlight relay (J) and the fog light relay (J7). It sounds like your issue it is before the fuses on the cabin fuse panel.
Your fuse at the battery is popping because that part of the electrical circuit was previously unfused. If this condition had happened prior to your fuse installation at the battery, you would have let out the magic smoke.
Tom

[dadaDaveed]

Ok, I solved the problem… sorta. After trying a number of things. I disconnected the lead from the battery to the starter to help isolate the main harness. That did the trick. Headlights are popping up and light up fine. So I must have mis-wired the starter somehow. Why that would create a short only on the headlight circuit??? I dunno. I have some exploring to do… but that'll have to wait for another day. I'm off to Austin for work.

Thanks for the help guys! (IMG:style_emoticons/default/driving.gif)

[Tom]

dadaDaveed,
Since you have a conversion, it is going to be harder to help you as the prints we have no longer represent a true wiring diagram for your car. I would look back at what you have done with the wiring to make the conversion..
Since you removed the wire from the battery to the starter and the problem went away, there is an issue ( I bet) with the wiring to the alternator. Take that wire off where it connects to the starter larger post and hook the starter to battery wire back up. If it no longer blows fuses, you have a wiring issue that has something to do with the wiring between the alternator and the wiring in the dash. Go back over what you have done to hook up that Chevy alternator to the wiring.
Aren't you glad you put that fuse block in? (IMG:style_emoticons/default/smile.gif)
One more piece of advice, when you hook the battery up, leave one post hand tight so it will be very easy to remove in case something bad happens. Much easier to control an electrical fire if you can remove the power quickly. This holds true anytime you have been doing electrical work and always disconnect the battery when working on the electrical system. Removing the negative battery cable is all that is necessary.
Tom

[dadaDaveed]

Yes, the battery side fuse panel has done a great job of keeping the smoke in. I'm very glad I got it. Thanks Tom!

So my mistake was to make multiple wiring changes between attempts (as I was quickly running out of fuses and patience). At the same time that I removed the starter wire from the battery, I also swapped out the headlight switch. I used a later style switch and left the 56K terminal unplugged. That was when everything started working again and I guessed it was because of the starter/alternator wiring being removed from the equation.

Last night, I double checked all the alternator, starter, and engine harness wiring and it all checked out. And with everything reconnected, the headlights were still working. So that left me scratching my head… but happy that the car was cooperating.

Then I noticed my cluster lights not working… dirty rheostat on the new switch? With only the parking lights on, I turned that rheostat back and forth to clean the contacts and eventually the cluster stayed lit. I then pulled the headlight switch and POP! Killed another fuse. Not moments before, everything was fine. Hrmmm…

So I double checked the wiring of the cluster. It's all correct. Then I realized my hi/low beams aren't switching. Perhaps a bad headlight dimmer relay. Maybe that's causing the short? I dunno, maybe not… but I swapped it out tonight and all is well again. At this moment everything is wired up and the headlights are working! The hi/low beam switch still does nothing. No click at all, so I suspect it's a bad ground or the wiring in the column. I'll check that out later.

So, I'm moving on down the checklist and hoping I've seen the last of the mysterious headlight short. Thanks for the help guys!

[dadaDaveed]

Update: The old headlight relay had 4 terminals and was in fact a dud. I'm pretty certain it was the source of my original problem.

The replacement is a 5 terminal and after creating a jumper from the 56 to 30 posts, my high beams switch perfectly.