Electrical Problem

[87chevysuburban]

I have a 1987 chevy suburban that i just replaced the computer in. The fuse for the battery, fuel tank, engine heat and oil gauges keeps popping, I have put a 30 amp fuse in it and taken it to an auto electic place and they cant even find out why its popping fuses. Does anyone know what would be causing this? I am thinking its a short somewhere but the place i took it to said that all the wiring looks good.

[84fiero123]

Did the computer you replace have the same numbers?

If not thats the problem, if it is the same numbers then you have a problem.

[unplugged]

Either you were quoted a flat fee to 'find' your problem or don't take your car to that shop anymore. Any shop worth it's salt would only give you an open ended quote to isolate an electrical gremlin. Troubleshooting electrical woes can take 15 minutes or 20hours or more. You have to be willing to pay a competent shop to find and fix e-gremlins. Computerized vehicles have made diagnosing electrical woes a bit more difficult. Any fault can be isolated given enough time and money.

Getting back to your problem.
1. Did you buy a new 'computer' or used?
2. Why did you buy a replacement computer?
3. Does putting the original computer back in eliminate the short?

For a DIY solution try this:
I use a tool that I made from an old sealed beam headlamp. It has a wire to the two contacts on the headlight and a spade on the other end that has the same size blade as my fuses.

Plug the headlight in place of the fuse that keeps blowing. The headlight will glow as long as there is current flowing through it. Now go to the farthest end of the circuit, and disconnect each component that is drawing current and when the light goes out, that 'leg' of the circuit would be suspect. Either the component itself or the wire to it.

Here are a couple of good resources:

http://www.forparts.com/ICsolvingint...ical.11.01.htm

http://www.shadetreemechanic.com/tsp...ricity_102.htm

[87chevysuburban]

Well the I bought the computer cause the truck was running really rough and missing really bad, the old computer was completely shot, the new one that i bought was re manufactured but tested with the shop that installed it, when my truck sat in the shop yesterday for the fuse blowing, the let it run for hours and it didnt blow a fuse, now when i took it from the shop and drove it around for about the first 15 minutes it blew it, i replaced it with a 30 amp and as soon as i started the truck again it blew instantly. It pretty much blows fuses randomly. i am going to take it to another shop here in a couple days to see if i get another story, i would like to figure out the problem myself though to save a little cash.

[TrailLeadr]

Do you park on an incline? I assume the shop's floor was flat, and level where it ran fine with no fuses blown. If you didn't park somewhere level, then I'm thinking it could be a hanging wire, or something that is push/pulling on the wire (gravity) that is causing it to short.

[unplugged]

If you want to save some cash, get the wiring diagram and use that headlight tool I mentioned earlier. It really isn't that hard to trace the circuit. You have the best clue right in front of you, the blown fuse. I repeat do not use a higher amperage fuse in that circuit, it will cost hundreds of dollars more to replace a damaged harness.

Here is a link to some very good info on troubleshooting electrical shorts. Check out Technical article #11 on 'Diagnosing Body Electrical' Page 9 in the article gives a good outline for you to follow. File size is 1.31mb

http://www.autoshop101.com/forms/h11e.pdf

[Steve]

I agree, there is a reason that fuses are rated for the amperage that is listed, it's to prevent too much juice from flowing through that and into parts that aren't designed for that much power.

It's not blowing fuses randomly, something is causing each fuse to blow each time power goes through it, when a fuse blows you just have to trace back down that circuit from start to finish and you will have to answer somewhere.

[Sawfish]

Check the wire to your temperature gauge sending unit. The placement of the sending unit makes intermittent contact of the wire and the exhause manifold almost a certainty at some point. Install a wire hanger to keep the wire away from the hot manifold, or zip tie it to something.