[allen smith]

I have a 1970 GTO with a pair of PY park light repair socket and wires spliced into a `72 front light harness. Had this in the car for 6 yrs with no problems. I took the housing loose from the valance recently, but no wires were disconnected, and not even the ground was disconnected. Tail light sockets were unplugged. All completed this winter before taking the car to the body shop. When I put everything back in place the park light fuse blows immediately. No corrosion is in the sockets noted, and after very close inspection, no broken wires. The body shop did get the car wet when sanding, but again no corrosion noted in the sockets. The turn signal lights work both fron and back, and brake lights. I have unplugged the rear tail light harness and tested, but fuse still blows, so that should eliminate anything going on with the rear. Any thoughts greatly appreciated.

[steve v]

I would check the splices first, it's possible there's a weak repair up there. Next I'd use the process of elimination to find it. Make sure you unplug the rear harness at the fuse block as there could be a problem with a seat bracket pinching a wire or damage to the intermediate harness if they did any floor repairs. You can unplug the front harness at the bulkhead connector too & if the problem persists you may have problems with the switch or the under dash harness.

Electrical repairs are usually a simple fix, finding them is the hard part!

[allen smith]

thanks Steve, and there was no floor repair performed and my interior was kept intact. You strike up a great point with the splice in the wires. Even though they were soldered and heat srinkers used, maybe all the moistered they endured during the wet sanding was enough to cause a disturance there? I believe Im going to pull the splices apart and re do the repairs, and see what happens.
thanks and I will let you know what happens

[allen smith]

I am buying a new front wire harness, and am officially giving up in diagnosing. I do not believe the problem is the splicing, the intermediate harness runnung from the das to rear and insected them all very closely. Very frustrating, and I have never had a perfectly operating car taken to the body shop to return with electrical problems.

I carefully made sure all wires at the park lights were not touching anything too.

[steve v]

Allen,
Does the short go away when you disconnect the front harness at the bulkhead? IIRC there's a 5/16" head bolt to the fuse block from the firewall side, undo it & both the front harness engine harness will unplug. At least you will confirm it is the front harness before you replace it.

[allen smith]

OK Steve, I'll try that and see. I may have to wait until the Food Lion Auto Fair in Charlotte is over, plus I need to get away from the situation for a few days.

By the way, you say after unbolting the fuse block from the enging bay side the front light harness should unbolt. Just to be sure in case I need a new front harness, did you say a new 1970 light harness should plug in the 1972 fuse block at the same location?

[allen smith]

I replaced my front park light / headlight wire harness believing this was the culprit, but it still blows the fuse. The harness needed replacing anyway, so no big deal. I then unpluged the tail light harnesses again, and again the park light fuse blows. Keep in mind the electricals worked fine before going off to the body shop. Interior was left intact. I am wondering if when the body shop was installing the new window wipers they inadvertently stepped on the wire harness under the carpet and ruptured a wire, between the fuse block and the trunk???
I wish there was a way to track down the short, but with the fuse blowing Im unsure what to do, short of pulling the carpet back / removing the rear seat

[george kujanski]

If you replaced the bulbs at the same time, is it possible you put a single contact bulb into a double contact socket? If you look inside the taillite/brakelite socket, there are two round contacts for the bulb which has two filaments.

George

[allen smith]

thanks Geoarge, but I unplugged the tail light harness and the fuse still blows. A friend asked me on the phone this afternoon if I had tried unplugging the intermediate wire harness from the light switch. He said if the problem still exist it should be the switch that is bad. Havent tried it yet, but makes sense. What do you folks think?

[steve v]

The rear harness can be unplugged by the fuse block, just left of the brake pedal bracket. That will eliminate the section of wiring under the carpet if it still pops the fuse with it unplugged.

Check the bulbs again, as George suggested an incorrect bulb even in the front turn signals may be the culprit, or it's possible one of them may be shorted.

[allen smith]

thanks Steve, I am going to recheck the bulbs everywhere sometime Wed or Thurs and unplug the intermediate harness at the place you indicated too. If the problem is not to be found at the intermediate OR the switch, could a correct bulb be shorted?

[steve v]

Instead of saying shorted it may be better to just say there's a problem with the bulb or socket. It could be one of the contacts in the socket has twisted, possibly grounding out to the base of the bulb. Start with the easy stuff first (bulbs, plug ends etc) as a lot of times that's where the fault lies.

[2002Z4CSS]

Disconnect the rear wiring harness connector from the fuse panel and see if the short is still there or not. That will at least point you to the general direction.

["QUICK-SILVER"]

Allen "Interior was left intact. I am wondering if when the body shop was installing the new window wipers they inadvertently stepped on the wire harness under the carpet and ruptured a wire, between the fuse block and the trunk???"

That body ribbon is tough, so I doubt stepping on it could've caused any damage. I have seen muffler shops add tail pipe hangers and shoot metal screws through the body ribbon.

Allen "He said if the problem still exist it should be the switch that is bad. Havent tried it yet, but makes sense. What do you folks think?"

I'd say most unlikely on the switch being bad.

Allen "could a correct bulb be shorted?"

Definitely as others have already mentioned.

Allen "I wish there was a way to track down the short, but with the fuse blowing Im unsure what to do, short of pulling the carpet back / removing the rear seat"

You can check for shorts with the fuse blown. Take all the tail/park/marker bulbs out, and unplug the body harnesses. Then check all the brown wires to ground with an ohm meter. OR Take a simple test light hooked to battery (+) and probe the brown wires untill the test light lights up. With both ends of the body ribbon unplugged the test light would tell you in a hurry if there's a short to ground in it. All this testing can be done with headlight switch off and battery left hooked up.

Another way to look for shorts: Hook a test light between a battery cable end and battery post. Positive or negetive side will work. Put a new tail light fuse in and turn on the parking lights. The test light will protect the fuse from blowing and any short will light up the test light. Then you just start taking bulbs out and unplugging connectors till the test light goes out. When the light goes out, you've found the problem area.
On that test, hooking a bulb or test light up in place of the tail light fuse, would probably be better than hooking it up at the battery cable end.

Put a little thought in this and you should be able to find the problem in a hurry.
You've pretty much got it narrowed down to the body ribbon already. Unplugging it under the dash will tell the tale.

Good luck

[allen smith]

Originally Posted by steve v

The rear harness can be unplugged by the fuse block, just left of the brake pedal bracket. That will eliminate the section of wiring under the carpet if it still pops the fuse with it unplugged.

Check the bulbs again, as George suggested an incorrect bulb even in the front turn signals may be the culprit, or it's possible one of them may be shorted.

I see where the wire harness ribbon ends, but then it begings into another tubing, running up the side of the fuse block, but I do not see a plug in?
Also, If I want to test the switch only, I only see one plug in on the light switch, so if I unplug it then there is no way to power activate the circuit for testing? I do have a new old stock switch in the box never used, so I assume I can just change them out for testing

[steve v]

Allen,
Here's a pic from my 70, red arrow points out the rear harness plug in.

[allen smith]

Thank you tremendously Steve, I am going to give the thing another look Thursday afternoon. I will take a mechanical failure any day over electricals. I can only tolerate working on this problem a little at a time so I dont get so frustrated.

This is getting it narrowed down to the switch or the intermediate harness. My brother is an electrical engineer working on automation equipment for GM in Detroit, but between doing that and teaching at UNCC he seems to never have any time to help, so I really appreciate everyones help here.
I`ll see what happens tomorrow and let you know...

[robz]

Originally Posted by steve v

Instead of saying shorted it may be better to just say there's a problem with the bulb or socket. It could be one of the contacts in the socket has twisted, possibly grounding out to the base of the bulb. Start with the easy stuff first (bulbs, plug ends etc) as a lot of times that's where the fault lies.

I totally agree...I had the same thing happen to my driver...Drove me crazy...Fuse blew every time I turned on parking lights...I removed all bulbs in rear and put one back at a time until the fuse blew again...Found the culprit. The socket had one of the side grnd contacts touching the positive one ever so slightly, after I changed the bulb, and caused it to short. Quick fix but long diagnosis....

[allen smith]

Thanks Robz,
Like one of the previous post noted, the problem is usually a simple one, but sometimes difficult to find. If I dont get it diagnosed today, then Quick Silver had some ideas that seem very good too. I have to be in the right frame of mind before entering into the garage on this one, I suppose the way a man has to be in the right frame of mind upon entering the house when the wife is in a bad mood.

[robz]

Originally Posted by allen smith

I have to be in the right frame of mind before entering into the garage on this one, I suppose the way a man has to be in the right frame of mind upon entering the house when the wife is in a bad mood.

You hit the nail on the head on that one...

Electrical gremlins are sometimes the toughest to resolve, but patience is a virtue here....