Major Electrical Problems, PLEASE ADVISE....

[nater]

NC_VX, sorry, I'll try another description:

The circuit between the power supply (the battery) and the load (like a light bulb) contains quite a few connectors. If you are blowing fuses (instantly) then you have a short. Shorts are caused by trauma to the harness or a faulty load (like a wiper motor that has shorted internally).

You need to find the location of the short. To do this, disconnect the circuit halfway to the load. Find a connector (using an Electrical Wiring Diagram) that is halfway to the load. Unplug that connector. Now, supply temporary power (WITH A FUSE OF SAME AMPERAGE!) and ground to that load using the appropriate pins. If the fuse blows, the short is between the connector and the load. Therefore, move to a connector CLOSER to the load in the circuit and repeat.

If the load turns on (light bulb lights up, wiper motor turns on, or whatever it is you are trying to diagnose performs its normal function) then move to a connector FURTHER from the load in the circuit and repeat.

LEAVE ALL CONNECTORS DISCONNECTED until you find the short.

I promise you, the short WILL manifest itself as either something bad looking (like a pinched wire, evidence of a drill bit through the harness, etc) OR it will show up as a bad component. You can verify the component is shorted by applying power and ground "on the bench" and see if it operates or if the fuse in your test wire blows.

This is the most efficient way to find a short other than guessing. Also, try to consider the difficulty of getting to a connector when pulling one out.

This task is almost impossible without the official EWD (Electrical Wiring Diagram) from Isuzu.

This process is called "split-half." Basically, split the harness in half, test one half, if it's bad, move forward, good, move back. Split the bad half in half again, test one half, and repeat.

I have years of experience doing this; I have never failed to find a short or open using this method. As long as the problem isn't intermittent! To trace an open, use an ohmmeter to check for continuity. You can also use an ohmmeter to check for continuity to ground on a power wire. However, this will not find all shorts all the time. If you are a professional, you can buy a special box that is a self-resetting circuit breaker (so you don't have to use up fuses) or you can buy a short circuit locator like one of these:

http://buy1.snapon.com/catalog/pro_d...re&dir=catalog

For at home work, your minimum is the EWD, some wire, a fuse holder, and a handful of fuses.

Nate

[nater]

Oh, I almost forgot,

NEVER, NEVER put power into a harness that has a yellow connector or is wrapped in yellow wiring loom or tape.

THIS IS THE AIRBAG!

IT WILL BLOW AND COULD KILL YOU if you power and ground the wrong two pins.

Nate

[NC_VX]

Wow, this is like goign to automotive school! I had to put aside the project until Tuesday due to going out of town this weekend. The guys are going to help me figure it out, but this direction also helps me appreicate the work they will put into fixing the problem! If I find a wire that has been damaged or exposed, can't I just wrap electrical tape around it and call it a day?

[nater]

Maybe. There are two goals in repairing a damaged wire:

1. Maintain the connection. The wire is stranded, so if half of the strands are broken, then only half of the electrical load (amps) can be supported. Fix this by replacing with a solder, crimp, or a piece of new wire of same gauge.

2. Insulate the conductor. Pick your poison. My favorite is shrink tube (get it anywhere, home depot, radio shack, etc). It goes over the wire and repaired area, and shrinks to seal when heated with a heat gun (or hairdryer maybe...). For a very small nick in the insulation, silicone sealant works well. You may have to put on more than one application. Electrical tape has a temporary characteristic. It gets brittle when weathered, and the adhesive gets messy over time.

Nate

[NC_VX]

Exposed wire in the rear that was rubbing against metal. 10 minutes to fix... WHy didn't they find it the last time they took the back bumper off? Beats the hell out of me!

They shined her up all pretty again and I get another car detail in a month, so I am not complaining. I printed a few of the links I found to fixing the probolem and they were greatly appreciated by the crew at Body Works Plus!

Thanks everyone, this thread can be officialy closed, my problem is fixed!!!

[Anita]

Whew!! Good to hear that!

[NJVX]

Hey NC_VX

Glad to hear that you fixed the problem. Electical can be the biggest pain in the A _ _ . But you fixed it. Remember that most fuses handle more than one job. But if a fuse is constantly blowing out when you do one thing. Like putting it in reverse. Most likely the problem is in the reverse circuit. So hopefully you don't have any electrical problems in the future, but if you do just think back to this situation and try and isolate the problem. It was the wire that goes back to the reverse lights that was frayed. Causing it to blow the fuse only when you put it in reverse..........Ok thats my 2 cents....lol

Dean