#1 fuse keeps blowing

[TX82FIAT]

82 Spider FI and the #1 fuse keeps blowing.

Purchased the car about eight weeks ago. Did not have to do a lot to get her up and running. The electronic systems were dull so I cleaned and replaced the grounds, No brown wire issue at this point. Lights are now bright. However, When I took her out for her first real test the #1 fuse blew. It blew at about 5200 RPM. I replaced the fuse thinking it was an old fuse. It blew again about 10 miles later. I had to try another fuse as I did not want to drive home without brake lights or turn signals. This fuse blew when I simply turned the ignition switch to the fisst position with a spark.

I know the pink wire coming in to #1 is from the ignition switch and the pink with black stripe is coming from a relay. Nopt real good with electronics. Assume I could pick up a multimeter and apply to the wires and see what one is drawing the heat. Maybe I can just unplug each wire and see if the fuses continue to blow. If it is the pink wire should I assume it is an ignotion problem given the direct connection from the ignition to the starter. Really a wird deal since the car is running great with the exception of this fuse. All electricals were working great prior to this fuse issue.

Any thoughts on what I should do first and what steps you would recommend to isolate this issue.

[ORFORD2004]

Find yourself a good wiring diagram and remove one wire at the time to isolate the short. Then when the fuse stop blowing, you have your faulty wire. Use the wiring diagram to identify that wire and what it control. Patience and logic is the key here.

[brunorahl]

Make sure you have the right amp fuse. It may have something small in it that can't hold up but was put in before when a previous owner couldn't find the correct style and amp they really needed. Then get the paper out and start squinting.

[rlux4]

You can get a good set of wiring diagrams here:
http://artigue.com/?page_id=3
Does the car die when the fuse blows? The pink with black wire goes to the dual relay which is critical for contacts to the ECU and fuel pump. If the car still runs, you probably have a bad emergency flasher switch. Check amperage on the light blue with white wire on the other end of the fuse holder, it goes to the switch.
Ron

[TX82FIAT]

Ron, Thank you! yes, the car runs. I disconnedted the blue wire with white stripes and the fuse does not blow. Reconnect and the fuse blows. The blue wire is definetely hot. I have been tracing the blue wire looking for it to hit ground or be exposed someplace. I did get a little shock as someone previously used a piece of wire coat hanger to hang a bundle of wires. In some ways this is a good sign because the short should be in the area of the wire hanger. It was not. I can't seem to fine the short.

I'm going to radio shack to buy a multimeter that I can use on the car. Not sure how to use the multimeter in a 12 volt direct circuit to find a short. Do I hook it in parrallel to find the hot area? Sorry, not real strong with electronics, I think I scared the family as they all stood around the car with the dashboard out. I know I can find this short if I just keep looking. Ray

[rlux4]

Which blue wire with white stripe did you disconnect? (Location?)
Ron

[TX82FIAT]

My mistake. It is the light blue wire with the wite stripe on the #1 fuse. When I unhook that the other circuit - white wire works fine and I now have a functioning fuel gauge. I picked up a multi meter that read amps today. I'll read the instruction tonight. The folks at radio shack or the auto parts store could not offer any help on how to trace down a short. I hope checking continuity will show where a hot wire touches or what other issue it may be. Also, I put a new hazard swicth in before the wire became hot. The turn signals started working after hazard swithch installed. I don't think it is the new hazard switch from IAP. I still have the short when the hazard switch is not plugged in. I have the dashboard off to trace all the circuits. Nothing looks out of order on the relay under where the glove box was. How do you test a relay? Thanks, Ray

[rlux4]

A short to ground on a hot wire is hard to find without tracing the wire the whole length. Because it's grounded you'll just find that you have continuity between the wire and ground when you check it with the multimeter.
The light blue with white wire goes to the hazard switch as you've no doubt seen, so if your switch is good then it's got to be (A)in the wire somewhere. You'll loose the wire as it enters a bundle, so look for somewhere along the bundle for an area with the outer wrap looks cooked. Or (B) the next step would be to disconnect each corner's marker lights one at a time, it could be in or going to one of them.
Ron

[TX82FIAT]

Tracing the wire in the AM before work. It is too hot after work to work in the garage in Texas. Seems like unravelling the budle of wires is the only way to go since I unhooked the tail lights and still have the short. However, looking at the way the circuits run it could still be in any wire between the fuse box and ground. I am considering replacing the entire wire if I can not find in the next few days. I don't plan on selling the car any time soon but I will tag the wires with the original colors so I'm not one of those prior owners doing monkey electrical work.

Ray

[rlux4]

We should be placing out bets now.
I'm betting it's not in that wire, but somewhere on the other side of the emergency flasher switch. Wouldn't hurt to clean off the holder for the fuse in the fuse panel and give the ends a slight squeeze to ensure good, solid contact. A poor contact causes resistance. Just a thought.
Ron

[zachmac]

We should be placing out bets now.
I'm betting it's not in that wire, but somewhere on the other side of the emergency flasher switch. Wouldn't hurt to clean off the holder for the fuse in the fuse panel and give the ends a slight squeeze to ensure good, solid contact. A poor contact causes resistance. Just a thought.
Ron

BUT Ron, with a fixed voltage high resistance causes low current flow, not high so the fuse wouldn't be blowing.

That same wire also feeds the Exhaust Gas Sensor (O2 sensor) light on the dash and the back up light switch. If you disconnect the plug from the hazard switch and reconnect the wire at the fuse box does the fuse blow or stay intact? This will eliminate (or confirm) whether the problem is post emergency swith components or the light or BUS wiring / components. You go at this a section at a time.

[rlux4]

I hear you Jeff, however, a poor contact at one or both ends of the fuse contact will cause resistance. This would cause low current flow, I agree. I'm not an electronics ace, but it's been my experience that if current demand is more than supply it would cause a fuse to blow. Sorry if I used confusing or incorrect terminology.
Ron

[TX82FIAT]

The wager will be a nice beer. If you ever saw the late eighties film "let it ride" with Richard Dryfuss. One of his disfunctional buddies is trying to get him to relax and tell him to "have a nice beer Trotter". I need to relax and just keep hitting this. I'll post a pic or two when I find the issue.

Cleaned the fuse box three weeks ago and think the contact is good. I'll hit is again so that it shines and is tight. The hazard is unplugged, the right and left tail lights are unplugged. The gas sensor does not have a bulb in it and is a pretty simple circuit. I think that leaves a delay switch and a backup light switch that are still plugged in. Given the fact that a prior owner (I love that--- the last guy did it) pushed a copper wire hanger "through" the wiring harness to hold it up against the dash board frame support and the fact that said copper wire gave me a shock as I removed it.... hello, unhook the - terminal rookie. I think it is in the wire between the fuse panel and the hazard switch.

That brings me back to a wager of a nice beer. Appreciate the help and would like to share a cold one with you folks at some point for all your help. I have not done this type of work in over 20 years and while frustrating...I'm enjoying the fact that I can roll up my sleaves and fix something on a fine car again. Pride in ownbership takes on a new meaning teaching the kids how a car works!! Can't do that on the other cars. Ray

[TX82FIAT]

Strange days....

Unhooked all items on the circuit, fuse still blew. As mentioned before took dashboard out carfelluy cut open wiring harness and pulled out all wires in the circuit and visually inspected for burnt marks, exposed wires, cuts or kinks. Did this throughout the entire circuit all the way to the ground in the trunk. Took the wires on the problem circuit out of the wiring bundle completely so they were not touching the other wires. Did not see anything that gave me any concern. For grins, I verified everything was unhooked from the circuit again and turned the ingition. THE FUSE DID NOT BLOW! One at a time a rehooked all items back to the circuit thinking it was a switch or electrical device. Everything worked well. In fact, I started checking other items and they worked better as well. At this point I'm not sure if I hit my head as some things like the wipers were working better than ever!

I have a few thoughts on this at this point. I did have a short as I recived a shock when removing a piece of copper wire that was pierced through a bundle of wires to hold the harness to the dashboard support rail at about the mid point of the rail. Again, could not see any sings of a short. virtually all wires were moved from orginal resting place for 28 years as I looked for the short.

Possible next steps. Before putting everything together and haveing the same problem again in the future:
1. Run a compass over the circuit while hot to see if flux from an open circuit sends the compass nutty. That should indicate an exposed wire.
2. Wrap the light blue wire with white stipe in elecrical tape. Quick fix in event I am missing an opening in the wire.
3. Use a combination of electrical tape and some of that plastic flame proof wiring harness stuff you can pick up at radio shack to keep all wires in bundle away from any metal and potential for grounding a hot wire.

Finally, put it all back together and pray.

Any thoughts or steps you guys would take?