1997 Dodge Pickup - Wiring Gurus Needed

[DaltonTire]

alright so customer comes in, says a squirrel got into some wiring and chewed some wires, well when it gets here its a no start, naturally from fighting with them before i replace the cranksensor and it crunk and ran about 5 times, then wouldnt recrank, checked the sensor and the sensor had fried, so i warrantied it out and now have a good sensor, looked for other wiring issues under dash and found where customre "repaired" were the squirell had been, well ordering a wiring harness from lkq to fix that because there were wierd burn marks on multiple wires, still have 12+ volts to the one wire 5+ signal to the other and have a good communication line to the pcm and such on the third wire, if anyone has any ideas i would find it very helpful since im at a standstill, im thinkin the pcm is shot but do not know how to test it...

[Tim Martin]

Welcome to the Mitchell1 Shop management Forum. There are some real neat fellows on this thing. In due time they will be along and you'll get a chance to meet them.

I have not had that much experience with a 97 model but a few years ago I had a chevy that the wiring caught fire and I simply went to a salvage yard and got a complete wiring harness for under the dash and under the hood. That worked very well. I told the customer it was strictly time and materials. I replaced the wiring and it fired up and worked well. If I was doing this one, I would probably do the same thing. I have done alot of wiring issues in the past few years and wished I could a done it that way for some others.

hth

[steven kiser]

Years ago when there were no computers and modules i could just about rewire anything. Now i get harnesses out of salvage yards or new. There are so many wires now it compares to trying to rewire a communication cable (basically that's what it is) one wire at a time. The squirrel damage is minor comparing to the customer repairing it. One crossed wire and it's trashed. You may find melted wires anywhere on this truck now. If the person has insurance then the next step should be calling them. They may total it just because of all the issues. They've learned from experience, this is one time i would suggest listening to them.

[brianp87]

I see alot of rodent damaged vehicles a few a month. It dpends on the situation. comp ins cover the repair if it meets the deductible. we treat them different based on each case. But for the most part we repair the wiring. unless its chewed off to close to the connector or a shielded wire or something super special. did 2 last week and got one in today. we solder all connections and shrink them then wrap them in loom and tape. If someone else did repair id redo all that and start from scratch if they dont agree then I wouldnt do it.

[steven kiser]

A point here, we can't overlook the fact that if you're not accustomed to wiring issues especially melted and burned i would r&r. I've been around and also rewire, solder and shrink wrap but have been at it for years and have eased my way along. For someone who isn't schooled in wiring it may be a bit overwhelming. Blindly cutting and splicing can cause wire fires. I'm thinking that more damage was caused by the customer "fixing" the wiring. Because if this there may be damage further in the harness that won't be easily discovered. I've seen one wire melt in one location and everything looks great but a few feet away it's melted and bared a lot of wires in the loom.

[brianp87]

Exactly wiring issues get no quote its repair as needed and charge accordingly you never know were they ate and they fit in places you cannot see.

[DaltonTire]

im accustomed to soldering and heat shrinking wire the thing is tho it would cost more labor time to repair the wires that could be damaged then to buy a junkyard harness, im in the process of finding a junkyard harness, and them possibly a pcm if the harness doesnt fix it or giving the truck back, found out today the customer has already been to 3 other shops, one turned him down without diagnosis when they heard it was a wiring issue, one started diagnosis saw the wires and sent him elsewhere, then the third said he wouldnt touch the truck without a harness, then he cam to us, so after we find a harness he may just decide to take it home, part it out, or wutever he chooses...

[ricmorin]

I had a Chevy cutaway that melted the entire dash harness due to a Chinese fuse that never blew. I went to the junkyard and pulled my own harness. This harness went across the entire dash, down under the drivers seat and out throught the fire wall. Charged every minute I worked on both vehicles including travel time. Still cheaper than a factory harness, which was on galactic back-order.

[steven kiser]

The post has turned from the basic question of how, to charge accordingly and rightly so. A customer can see a brake system that's gone to metal on metal and other repairs along that line. I love being able to point at something and say "this is why it is costing so much". many people are afraid of the unknown in their vehicles and i think feel if they can't see it then it shouldn't cost that much. This is one reason the internet is my friend. I know that it's going to be investigated.


My basic feeling is that since this person has been to other shops feeling them out he's just a tire kicker you really don't want to associate with. when i get a grenade like this an a quote is requested i (take this post as an example) will call the dealer or salvage yard and inquire on the cost of a harness, depending on the vehicle quote 10 hours and up. Give that to the customer and say it could be less. A great point was made about taking the harness out yourself. It's the only way i'll do it. I take a package of those paper tags used to stick on things and make notes on and tag out as many leads as necessary. I've been hit with a clipped harness or two in my day and it's no fun.


This post covers two great issues that we face. How to deal with the hidden little treasures like burned harnesses and quoting prices to repair it. If you try to be a good sh**t and repair it you own it if anything pops up in the future that can be traced back to the harness. What i've done in the past with harnesses is after i've swapped them out i take the old one slice the tape away and pull it all out like spaghetti. As funny as it sounds it makes it look worth the money i charge for it.

[DaltonTire]

well harness didnt fix anything, so i put everything back its still a no start however been scopin out wires and checking things here and there during free time,found it keeps frying crank and cam sensors without it running and im not gettin the appropiate square wave with the scope on it so i got to checking voltages and found on pin 6 and pin 7 on the ecm 6=6v supply voltage and 7=8v supply voltage and instead of six and eight volts im getting 12.3v out of pin 6 and 17.7v out of pin 7 roughly double the voltage to my supply line and it doing this with two different ecm's, anyone have any ideas, ive never seen this happen before....

[mopwrforme]

garbage in garbage out, ck for exccessive voltage applied if your getting 17.7 output after the ecm reduces
it I would be curious what the voltage applied is. I guess you could fill up a library with the shi!!!! I havent
seen. but thats a new one on me. I have access to chrysler dealer connect Ill ck. that in the morning.and post
what I find. good luck

[Cory]

I seem to remember a Chrysler car that I battled once. I would monitor the voltages and unplug other sensors to see if or when your problem goes away. Are all the fuses good, I do a lot of electrical and have seen some weird stuff.

[DaltonTire]

i appreciate it guys, all advice is appreciated...

[steven kiser]

Ok, look at the cable ends on the battery. Are there melt marks from the cables being crossed? You may have to leek closely because if the final contact was made on the "donor" battery the burn may be hidden a bit. I still think that you're dealing with two critters here, the squirrel and the owner. Did a bunch of shade tree tech's get together with a case of bud and dig into this?

Obviously the battery voltage at the sensors is an issue. It's supposed to be 5v reference. I'm not sure if it's fed by the pcm or through an independent resistor. On older vehicles the feeds for the sensors were all fed through a common source. The harness that was damaged should be replaced plus like i stated before there may be other damage in other areas.

I would look at a schematic and see how they are fed. If it comes out of the pcm unplug the harness and check the pin in the harness for power. There may be a short in the harness that's feeding 12 volts to that feed. A sticky point here is that the harness that's unplugged may be the one feeding a relay that's part of the issue. I know i'm really confusing the issue here but with the harness unplugged the power supply to the short may not be activated. A crude example would be if the short is in the fuel pump circuit it would only appear if that was active. With the harness unplugged it wouldn't be and you'll start chasing your tail. What came first? the chicken or the egg? if there is a short to power in the harness it's obviously back fed into the pcm and trashed it.


I'm just confusing myself here but i hope you're getting the idea. I'm a lousy teacher but if you can put the information puzzle together i'm sure the answer is there. Wiring can be a bit confusing but it's not realy that complicated unless some one's been in there and muddled things up and you're dealing with the "unknown".

[mopwrforme]

Great point steven I would if you havent already skin back the wire in question about 6" from the ecm connecter
so you can solder and shrink tube it back togeather. then ck it it should give you your 5v after its isolated
if you still have 17.7v then stevens right ecm is trashed. if it is find your issue with the old ecm. cking pwr
applied and grds to the ecm us a headlight bulb to ck amps or curent flow. I think steven is right in that you
probably have a short to + on your 5v reff.