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post #1 of (permalink) Old 04-17-2000, 02:06 PM
broncoman
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Peculiar Electrical Bug

I have this strange electrical problem(I hate electrical). It seems to happen when Im going over a lot of rough road and all of a sudden my speedo dies, ABS light goes on and the light on the shifting stalk starts flashing(goes into some fail-safe mode). I traced it down to a blown fuse in the engine bay. Most times I replace it and all works again. But on a recent trip I had to replace the fuse bout 2 times in a 4 hour span.

I figure some frayed wire is short-circuiting somewhere???? Anyone come across this problem or have an idea where the rogue wire may be thats causing this?

thanx in advance

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post #2 of (permalink) Old 04-17-2000, 06:34 PM
**DONOTDELETE**
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Re: Peculiar Electrical Bug

broncoman - What is the underhood fuse fuse #, and amp rating?

post #3 of (permalink) Old 04-17-2000, 07:14 PM
broncoman
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Re: Peculiar Electrical Bug

I dont rememeber the fuse #, i'd have to check tonight, but the fuse rating was 15A. I believe its the only one with a 15 amp rating

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post #4 of (permalink) Old 04-18-2000, 01:58 PM
**DONOTDELETE**
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Re: Peculiar Electrical Bug

From info on a '94, there is a 15 amp fuse, fuse "E" underhood. This fuse feeds six items:

Cruise control actuator
HO2 Sensor (heater side of O2 sensor)
DRL (Daytime Running Lights module, your bio says Canada)
Auto Trans (just to power back-up lights through part of the switch on the trans.)
One ABS Power Relay (in the Trailering Relay Box)
4WABS module power

Speedo loss makes sense, as rear diff speed sensor feeds 4WABS module info, 4WABS sends it on to PSOM (speedo module), so loss of ABS module power kills that. 4WABS fail light come on if module dead. Trans. error light I theorize may be turned on by EEC since it sees trans turning, but no output at rear diff.

According to color code, all of the supply wires downstream from Fuse "E" are Purple w/ Orange Tracer, all except the 4WABS Power Relay.

First I would check any modifications... a stereo, lights, etc? added to this vehicle? Have seen people just look for any wire with switched 12 volts to tap into! DUH! Pull fuse and see if they die also.

If okay, the O2 sensor wiring down by it is worth a look. The color code is for the harness, the sensor wires themselves may have their own code. The ground for the O2 heater is Black. Wires down there bare or melted/burned, ?
Could unplug Cruise actuator under hood at the unit, and run that way to see if it repeats.
Can you unplug the DRL module in front of the driver side radiator area, and run without DRL for a while?
The back-up light you would think would only operate in reverse, lowering probability of it being the problem (unless it pops after putting it into reverse!)

If you can disconnect some of this stuff only one at a time, and see if the fuse problem goes away, that will narrow it down. But I wouldn't junk something expensive unless you can really prove that is the problem.

Post back if you get any more info, or have questions, we all can learn something.

post #5 of (permalink) Old 04-22-2000, 12:47 AM
broncoman
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Re: Peculiar Electrical Bug

I finally got a chance to look underneath the truck today and spent 20 min or so rooting around down below. Most of the wires are all in plastic housings so it seemed like I was look for a needle in a haystack. I looked at the O2 sensor wiring and noticed that some of the wiring was very close to steel parts. The wire that went to the O2 sensor branched off another wire that went to the starter( I think) and was very hard to get a good look at, but I managed to twist the wire around and could barely see some bare exposed copper!! Ahha!! My suspicions were confirmed when I moved that piece of wiring just 10 min earlier and when I went to start my truck, the ABS light stayed on and tranmission light started flashing (fuse had blown again.)

So i fumbled some electrical tape around the culprit wire and put some wire that was leading to the engine block inbetween the said wire and the part it was rubbing on. That should keep me blown fuse free for awhile.

Thanks for some of the ideas Don. I can now travel without carrying a load of fuses with me now! Probably saved myself a hundred bucks for some technician trying to find the problem.

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