Let's play "guess that wire!!"

[Cory]

First off I'm obviously new. I've been browsing, searching, and using the info on this forum for some time now and I have to say, I'm not sure what I'd do without it. You all have been a huge help already and I haven't even posted anything yet. Seems to be a wealth of knowledge on here.

Anyway, I have an '86 C10 short bed, originally a 305, but now has a 350 with a 700r4 automatic transmission. Since I've had it, I've gone through most of the wiring inside the cab and cleaned up a rats nest of extra wires from God knows how many stereos and whatever else. The good news is MOST of the wiring harness, inside and out is in fairly great shape with little to no hacks, just a lot of added wiring I've had to clean up.

My problem is, I have all sorts of wires and connectors under the hood and I cannot identify any of them. I am pretty fluent in schematics, as I use them from time to time at work, but none of the wire colors in the engine bay are really matching up on my schematic. It's the correct schematic for my year that I got off of this forum but there seems to be some wires left out on it. I'm ridiculously OCD and all these wires and crap hanging around the engine are driving me crazy. I'm trying to hook back up all of my original gauges as none of them work, as well as clean up the eye sore under the hood. Everything on the truck pretty much works and is in great shape, except for the gauges. I really just want to clean up all the loose wiring in the engine bay.

Before you ask, YES I have searched and searched, even on other C10 forums for the answers, and there's been a whole lot of topics on this, but nothing that really pertains to me. After spending another 2 hours tonight looking, I finally decided to just ask.

Here's the pictures:

1.....This looks like a light green wire. From what a researched, it sounds like maybe this is the temp. sender wire? Not sure though. The second picture shows where it goes into the firewall plug:

A


B


2.....This is another wire that looks a little darker green. It has a black connector on the end of it. The second photo shows where it looks spliced into the ac compressor wiring. The thick green wire in the second picture is going to the compressor, and the thin green one is the one in question. The THIRD picture is a black plug near the center of the firewall that both wires run to. Any ideas??

A


B


C


3.....The next wire is a black wire with green stripe that goes into the black terminal. This is on the left side of the intake if your standing at the front of the truck looking at the motor. It looks like a 2 wire terminal with just the black/green stripe wire going to it:



4.....The black wire with green stripe that I just talked about goes straight from the back of that black plug, right into this plug that also has what looks like a tan or brown wire with a black stripe. This is sitting a few inches behind the alternator, on top of the motor. Looking at the engine schematic, I don't see any tan or brown wires with a black stripe:



5.....OK the next wire appears to be dark green and has a pretty distinctive black plug on the end of it. It was laying across the evaporator I guess to get it out of the way. The second photo shows that it goes into that harness right above the transmission dipstick and then through the rubber grommet in the firewall. This is more towards the center of the firewall if you notice the red distributor cap to the right of the trans. dipstick:

A


B


6.....Ready for another? This plug is coming out of the firewall from the same grommet as the last wire I talked about, right above and behind the distributor. 4 wires, 2 of which are obviously light green and yellow. Again, from what I researched on here, I'm thinking maybe something to do with the ESC or something? I have no idea.



7.....Alright alright almost done. This looks like a vacuum switch mounted more on the upper left side of the firewall looking at it from the front of the truck. Wires obviously going in but it looks like someone cut the vacuum hose going to it. A mechanic who was servicing the AC told me it was probably for the torque converter lockup, but from what I've read on here, it sounds like the vacuum switch for that is more towards the brake booster on the firewall?



8.....OK last one. This has nothing to do with the wiring but while we're on the subject of disconnected crap everywhere, the hoses that run to what looks like a vapor canister (front right of engine bay looking from the front of truck) have been completely cut. Looks like 2 fuel lines (or vent lines) and maybe a vacuum line? In the second photo I'm holding the cut lines up, they are just laying over the front wheel well:

A


B


Any and all help would be awesome. I drive this truck every day and would like to get all my gauges going again and get all the other wires taken care of. Even if I dont need them, I NEED to know what they go to because my curiosity is killing me.

Thanks again!

[Captkaos]

I am going to go by numbers, so..
1 - Temp sensor wire
2 - AC compressor and fast idle switch to the carb
3 - appears to be a ground wire
4 - Looks like part of the Carb Accelerator pump wiring...
5 - Knock sensor goes to the side of the block
6 - Electronic Spark Control or ESC.
7 - This could be the trans lockup control, where do the wires go that is plugged in?
8 - Part of the vapor system, most of those lines went to the carb that came in the truck.



BTW, you are looking at this wiring diagram right: [size=78%]http://www.73-87chevytrucks.com/techinfo/7387CKMans//Wiring/ST_352_86_1986_Chevrolet_GMC_Light_Truc_Wiring_Manual_CK_10_30_Only.pdf[/size]

[Cory]

Thank you Captkaos. You are a gentleman and a scholar. I have a couple of questions though. In #3, what would that have been a ground for if it is in fact a ground wire? If it is connected to what looks like the accelerator pump wiring, would it be the ground for that? In #5, would I even need any of the knock sensor wiring if this is obviously not the stock engine and I don't believe there is any type of knock sensor on the side of the engine? In #6, I figured that plug was for the ESC but you confirmed that for me. Do I need this plug or wiring? I don't want to get rid of anything that could only give me the option of having the truck run better i.e. vacuum lines and such, but if it makes no difference with my setup, I want it gone to clean everything up. I would just like everything as stock under there as possible, with the exception of changing the engine out, anyway.

I will have to look at that vacuum switch in #7 and tell you where the wires go, hopefully I can look at it in a little while here and give you an answer.

And lastly the vapor canister in #8. Can this be removed since its obviously not being used? Would hooking it back up lead to better fuel economy or any other benefits? Or with my setup (350 crate) is it just useless?

P.S. the schematic I'm using is the one in the Tech Info section:
http://www.73-87chevytrucks.com/techinfo/wiring_diagrams/81-87_V8_engine.jpg

I looked on the link you sent me and its clearly different but the only engine bay diagram I see is for the straight six...?

As always thank you for the reply.

[Cory]

Here is a better picture of that vacuum switch in photo #7. As you can see the wires are going into that same harness and bulkhead fitting that the ESC plug wires go into...any ideas?

[nlauffer]

Just speaking about the last photo, #7, I thought that was the vacuum control for the ESC.  Just a quick look over, but in my opinion you can get rid of 4,5,6,&7.  I have removed all of these items on mine.  It is an 83, though, so I didn't have #4.  You will also have the ESC Control Box, or whatever it is called, under the dash behind the glove box if you follow the wires through the grommet.  If you remove those wires, don't remove the grommet or find another one that will fit, as the whole is quite large that it leaves. 

I have my truck dissembled right now and will try to take some pics of it, if I think it might help you chase those wires.

I know there are posts on here that show most of what you are describing, but I just didn't search for them, yet.  Try to search for ESC and see what comes up.

[nlauffer]

Also, I downloaded an entire service manual and some color wiring schematics from 67-72 website, I believe.  It may have been from here.  I'll check again and post the link.  The guy has a lot of them and all scanned.

[Cory]

That makes sense if #7 was the vacuum control for the ESC since the wires are going to what looks like the same area that the plug is. Does anybody know for sure? And if it is for the ESC, where is the switch for the converter lockup? By the brake booster?

That colored schematic might help out a lot as well.

Thanks again for the responses!

[Cory]

Captkaos, any word on if I am in fact using the wrong schematic? If so, where would I look on the ones you posted because like I said, all I saw engine wise was for a six cyl.

[nlauffer]

http://www.73-87chevytrucks.com/techinfo/7387CKMans//Wiring/ST_352_86_1986_Chevrolet_GMC_Light_Truc_Wiring_Manual_CK_10_30_Only.pdf

Here is a link.  It is in the Tech section under Service Manual link.  I still didn't find the link where I downloaded my manuals from.  I just did it 3 days ago.  I can send you the one for an 83 or 91.  I downloaded the 91 because it has some different ways of showing the wiring harnesses.  And for the most part, a lot of the wiring is similar.  Color changes I'm sure. 

Does your motor still have the original distributor?  If you have ESC and it is the original dist., you should have a plug with Br,W,Bl,&Grn wires that matches up to the larger plug you have.

In the wiring from ESC, through the grommet will possibly be 6 wires inside the cab, with only 5 coming through.  1 Dk Blue (maybe different on yours) will go to the knock sensor.  Br,W,Bl,&Grn go to the large plug.  The last one is pink/blue which should go to the fuse panel (ignition hot).

This is from my 83 manual and I don't know how much color change happened into 86.

[nlauffer]

Oh yeah, converter switch.  Do you have one that looks similar by the brake booster around upper left area?

[nlauffer]

Ok, I thought I was loosing my mind for a bit.  But, I found it.

http://67-72chevytrucks.com/vboard/showthread.php?t=545416 

Try this link, but read towards the top.  Right click the link and save as to computer.  Some of these are around 1500 pages.

[Cory]

Wow thanks for all the info nlauffer. The schematic I got off of the tech section for the engine bay was one page, and looking at the schematics on the link you sent, I am clearly missing a couple.

I don't have an ESC distributor anymore, I'm assuming that went away with the original motor. I will follow the wires you are talking about, all the way to the ESC box and more than likely remove the harness and box to eliminate a lot of that mess. That will take care of picture #5 and #6 right there.

Looking around my brake booster, there is one that looks similar. Its a little different but looks to be the same concept. I'm thinking that is the one for the converter by what I've read on this forum. Really not sure though...even if I figured out which switch was for the converter, would I still need it? I'm assuming its not hooked up but I could be wrong.

Thanks again for that last link and for the replies. I appreciate it!

[Captkaos]

What nlauffer linked are the exact identical to what I have in the tech section.

Also it list all of the engine layouts, and it is the actual GM manuals.

Unless you are still running a feedback carb, you can get rid of everything from 3-7, and 7 is the ESC sensor, you can remove it also.  Your lockup should be on the brake bracket.

[rich weyand]

Could the extra vacuum switch be the clutch cutout on the A/C compressor?

[Cory]

Captkaos I think my confusion was because the 6 cyl schematic is on the same one as the rest of them. I was thinking it would be on a separate page. I'm pretty sure I have it all figured out thanks to all of you.

My only remaining question is #8.  I have a 600 cfm Holley on top so I don't think that vapor canister would be of any use would it? Is that something I will need to hook back up or can it go as well? Either way is fine but I would like to take care of all the cut lines coming off of it by either hooking them back up or getting rid of them.

Thank you again for all the help.