Brown wire coming through firewall

[jbharkjr]

What are these wires coming through the firewall on the passenger side, rear corner of block, for? Specifically the brown wire by itself. There's one brown wire going to the clip which isn't plugged into anything and then there's a loose brown wire (going down in the picture). Trying to figure out what the loose one is for / goes to.

It's a 1986 Chevy C10.

[TKCR]

I have that on hanging loose also. I tried to go back and look at old threads to find out exactly, because I can't remember what I was told. But what I do remember, is that someone asked if I still had the stock engine, which I don't. The PO put a 350 in it, and so I was told the couple was no longer needed or used. But exactly for what, that's what I'm not sure of.

[jbharkjr]

Originally Posted by TKCR

I have that on hanging loose also. I tried to go back and look at old threads to find out exactly, because I can't remember what I was told. But what I do remember, is that someone asked if I still had the stock engine, which I don't. The PO put a 350 in it, and so I was told the couple was no longer needed or used. But exactly for what, that's what I'm not sure of.

Hmm, well I was assuming/thinking the loose brown wire went to a ground. I am in the process of replacing the 350 that was in the truck (not stock either) and I know the plug didn't go anywhere although I thought the loose brown wire did.

[jbharkjr]

Think I'm having either a battery issue, starter issue or ground issue.

Engine was turning over fine until I put the spark plugs in. Once I did that it seemed like the battery was dead. Very strained to turn over, if at all. Ground wires got really hot.

I had the loose brown wire connected to the firewall ground...think I'll un-hook that and leave the loose brown wire disconnected for now. Check all of my other grounds. And see if that makes a difference.

If not, guess I'll get my starter and battery checked out. The battery is only about 2-3 years old and the starter is even newer. Maybe a year old. BUT this is a new engine with slightly higher compression.

[TKCR]

I went out and looked, the brown goes to the distributer.

[jbharkjr]

Originally Posted by TKCR

I went out and looked, the brown goes to the distributer.

Really appreciate your help.

Where does it go on your distributor? The end of my Brown wire has the flat washer style terminal on it.

[TKCR]

Tried to get a good picture of it. I put the pointer on where it goes into the distributor.

[jbharkjr]

We must be talking about different wires...I do not think the one I am referencing would even be able to reach the driver side of distributor and if it did, I'm not sure how/where it would connect. Let me get some different angles to make sure we are talking about the same brown wire.

[TKCR]

Originally Posted by jbharkjr

We must be talking about different wires...I do not think the one I am referencing would even be able to reach the driver side of distributor and if it did, I'm not sure how/where it would connect. Let me get some different angles to make sure we are talking about the same brown wire.

From your 1st pic, your talking about the one brown wire that goes straight down from that bundle coming out of the firewall? the one with the connector not connected to anything. Well I went right to the same place, on my truck, and followed the brown wire over to the distributer.

[TKCR]

Here's a pic of mine, the loose plug is tucked behind the dipstick. There is a single brown wire, in that same bundle. I followed it over to the distributer.

[jbharkjr]

So we are definitely on the same page (thank you again btw)

So the only question I have left...how does it attach to the distributor? Is it a plug or a washer style terminal on the end of the brown wire?

[Tetanus Express]

How far down does the loose brown go to? The other brown that goes up out to the left of your first picture... Where does it go to now?

[Tetanus Express]

If you have have a one wire alternator disregard but if your still running the stock plug style alternator do you have a brown wire going to the back of it?

[jbharkjr]

Originally Posted by Tetanus Express

If you have have a one wire alternator disregard but if your still running the stock plug style alternator do you have a brown wire going to the back of it?

Yes there is a brown wire to alternator

[jbharkjr]

Originally Posted by Tetanus Express

How far down does the loose brown go to? The other brown that goes up out to the left of your first picture... Where does it go to now?

The loose brown wire is currently going into the back of block where the ground strap between engine and firewall goes. It seems to be a perfect length and fit.

[Tetanus Express]

Ok. So the brown wire that has I'm assuming an eyelet on it and is connected to the back of the head looks like it comes up to that plug that is loose?

The brown on the alt. can you trace it back to see where it is coming from?

Does the truck have working A/C or Heat?

[Tetanus Express]

If you have have a one alternator disregard but if your still running the stock plug style alternator do you have a brown wire going to the back of it?

[Tetanus Express]

Ok that was weird must have hit a wrong button or something? Lol. Don't know why it posted my last two posts again but anyway...

The brown wire that comes up and looks like it goes to a connector or is that a fusable link and then turns orange? If that is the case it may go back to the ignition side. Kind of hard to tell with out being in front of the truck and not knowing its history.

How long have you had the truck or if you've done any wiring on the truck or even worse has any of the previous owners done any hacking on the wiring? Which can really be frustrating to try and figure out. What they did and what they was thinking or the problem they were trying to fix.

[jbharkjr]

I'll get some better pictures of the wires and wiring harness that comes through the firewall. The brown wire, orange wire, etc are all separate wires completely.

On a side note, I added a ground from the alternator bracket to frame and also removed the mysterious brown wire from the back of the block and I was able to get the engine to turn over and crank.

I'll follow up with pictures of the wiring so maybe we can figure out what the wires are for. Beginning to think they were for the original engine and no longer needed.

Thanks!

[jbharkjr]

I think I need to add a ground also.

As of now, I have a ground strap between the firewall and engine. The Negative battery cable has a split with a small ground line going to the front clip and then the bigger gauge line going to alternator bracket. And the mysterious brown line is currently being grounded with the firewall ground strap.

Would it be ok/a good idea to install a heavy gauge ground wire from the alternator bracket to the frame?