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Where does this wire from the firewall bulkhead connector go? ( see pics)

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6.2K views 12 replies 3 participants last post by  Motor City Rick  
#1 ·
I don't remember and can't find where this single brown wire from the firewall bulkhead connector goes. I looked at another truck and thought I had it, but when I got to mine, it won't connect there.
 

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#2 ·
Its most likely for an option that your truck does not have. When the build new cars and trucks, they use different suppliers to get some of the parts from, like wire harness for example. There are almost always wires and connectors that are not used. Yours maybe just that. Or it could also something after market that was added by a PO.
 
#8 ·
Its most likely for an option that your truck does not have. When the build new cars and trucks, they use different suppliers to get some of the parts from, like wire harness for example. There are almost always wires and connectors that are not used. Yours maybe just that. Or it could also something after market that was added by a PO.
Yeah, I didn't know there would be so many. I have a wire to the transfer case relay location, mine is a 2WD, one to the auxiliary battery relay location, which I don't have, and another one I can't recall right now. I expected maybe wires for power seats, which I don't have, but not those others.

Well, it's back alive now. All the lights work. The fuse doesn't blow. It didn't catch fire. The new headlights and front marker lights are installed. All the bent fins from bug strikes on the condenser are straightened. The exterior wiring ground points were cleaned. I got the replacement spare tire lowering tube installed. Now I'll start spending money I guess. I want to get some stock wheels or 16" so I can get some smoother riding 75 or 70 series tires instead of these stiff 55 series on 18" wheels. I need a new ignition switch because this one sticks. I just remembered I meant to take it apart when I had the column out to see if it's that simple problem with the little spring. $@#%!!!!!!!
 
#4 ·
In your pics, I could not see where the wire comes from. If your worried about the wire shorting out and maybe causing issues, IMO you need to figure out if it has power or not. A test light will be very helpful to figure this out. Try key off, key on, truck started, ACC on, ext. Does it get hot with the headlights on? ECT. I know, you wanted someone to say yea thats the wire for blank, but I also have a 97 C 1500, and see nothing like that under my hood the best I can remember. I will look again tomorrow and see if I have that same wire, and where it goes
 
#5 ·
Kenny,
In the white, upper part of the bulkhead connector in picture 2, that wire comes through at the top, far right (closest to the driver's side fender). I have disturbed the original routing, so it is very likely that on yours, that wire will go down and be under or behind something. It might be taped to one of the other larger groups of wires.
The white connector plug on the end is ~3/8" wide, kind of flat, meaning not as tall as it is wide, and has a single wide flat contact strip in it. It is a female connector.
 
#6 ·
It probably goes down and wraps under and connects under the brake booster where you can't see it. I had the fuse&relay center loose and the cruise control module out of the way, and still couldn't see anything. They are just finger-tightened into place right now, so I can remove them again easily.
 
#7 · (Edited)
If that chocolate brown wire connects to the middle outside row of the bulkhead connector, ...then leave alone. Just wrap it back up as not to get it snagged or shorted to ground. Don't cut or wrap it out of the way in such a fashion that a diagnostic tech can't find it.

It's used for complex tests through the ECM with certain VIN letters. Not something a consumer would use or understand.

Better stop poking with the wiring on such an older vehicle, stressing 22 year old wires /connections could cause future electrical problems.
 
#9 ·
I never did take a pic of mine, because I figured Rick answered your question as to what the wire was. Rick is a top notch tech. We all have our back grounds, and although I was an auto mechanic, at 2 new car dealers, I have been a welder for a long time. I kind of got out of the loop in auto training. Along with all the welding I do, I also do a lot of equipment repair work almost daily. Also a lot of hearing press work, but someone like Rick has training I do not, so when Rick said the brown wire is for testing, I am sure, thats what its for so I didnt take a pic of mine. I figured it was wrapped up in the harness.
 
#11 ·
Hey Kenny, ...I do TIG!!! Can't stand MIG!!! Or other types of "Snot Welding".
Love doing those precision bead welds that can be ground away to look like no seam is present. Look at the picture posted below.

This was one of my old UAW Skill Trade card requirements.

My option was, build a computer monitor stand (for my monitor) with dissimilar metals, machine precision fastener attachments within .01 tolerance to mount the monitor housing support assembly. 50% or more of the welds had to be hidden after a TIG bead is laid. Also couldn't buff or scratch any polished stainless steel surface for welding. Had to maintain polished surface, no burning to metals whatsoever. Able to handle 10 times the weight of the monitor lateral movement as to prevent the monitor falling over in a 10.0 earthquake (that requires a "MAST Table" which shakes the chit out of the clamped down base fixture for up to 3 hours to validate). If there is any cracks, weld failures, bent items, ...then you have to restart again with better materials and design. Not as easy as it looks.

Option B was to re-weld a sliced aluminum pop can to a level of no leaks or seepage.

Option C was welding "cast" exhaust manifold that had a hidden hairline fractures and know how to prevent the cracks from getting larger.
Final part was pressurizing the manifold to 10 psi. It must not have any leaks or porosity from the welding.

Took the easiest test to pass. Here is my weld test:
Image
 
#12 ·
I do a lot of TIG work. Love it. Stainless, inconel, monel, steel, and aluminum. I also still stick weld, and wire feed. Like you wire feed is my least favorite. I cant post my work. Our work has copy rites, or most of it does any way. I have been at this machine shop going on 3 years. Being a job shop you never know what is coming in the door next. Our biggest customer is an oil well service co. We get into a lot of high pressure, close tolerance work. There equipment sees extream pressures and torque. Then we have 4 bearing presses. 2 of those are 150 ton and a 300 ton so we get some big press work, along with the shade tree mechanic front wheel bearing work also. Its very diverse. Doing press work, we rebuild a lot of gear boxes. We also build donut glazers for most of the local donut shops. We dont turn down many jobs, but we do not do engine machine work
Your welds look good by the way.
 
#13 ·
I worked for super quality nuts. Everything had to be more than perfect in anything you did, ...or you went to dirty slimy dungeon and did chit work which was diesels and all their oily problems. From cars to super heavy duty truck teardowns - rebuilds.

That was our motivation to do things right the first time.

Barely avoided doing military Hummers and military support vehicles where everything is beat to chit!!!