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justinevert

HELP!! Re-wiring, something I don't Have a Clue At All

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Ok, now things get interesting,

Now that I have finish the front end rebuild, rear disk breaks fabrication, small block freshening, trunk clean up and now waiting on the head to be rebuilt, I have now started on the engine bay redo and rewiring.

In short, I know absolute SQUAT about, electrics. The only thing I know about them is:

1) How to put batteries in

2) How to change fuses

3) Know the difference between light and dark

4) Know not to stick my tongue on a 9 volt

5) That sticking a ket or penny in a plug socket is going to hurt

So far I have been able to pull the gear box, the pedal box, master cylinder/ brake booster, and ancillaries (coil, washer bottle, washer hoses etc,) and firewall blanket (good news there's no rust behind it). My game plan is to wire-wheel every square inch of the engine bay, prep and POR15 and repaint, and reattach everything accordingly with the wiring harness be replaced WITHOUT all the emission and EGR crap. Looking at the current state of the wiring there has been some damage from the rat tennants as well as serious splicing and rube-goldbarbing.

Before I did that though I tagged all the connections to use to compare to the new (well lightly used) wiring harness Now I have been able to remove the wires from the lights and horn, the fuse box connection (a nice place for a rat-condo by the way) but now I am stumped on how to be able to separate the wiring harness to fit though the two 25mm holes under the dash. There is no major connection set that separates the engine bay wiring from that of what is under the dash, it is all interwoven. I am in awe how they connected everything at the plant in the first place.

What I don't want to do is to cut the harness I think this would cause more harm and confusion but I am stumped on how to separate the wiring between the two areas. There are no major connectors on either side of the firewall (that are usually found in most cars) and there are connection that are too big to pass through the holes, it is the rubics cube of wiring.

Looking at the newer harness, it looks like there are 3 sections; one for the coils and distributor, sensors, the other looks like the main concentration where the fuses go and the third I don't know. I do have the color-coded wire schematic which is a huge help but trying to remove the old harness in it entirety is my biggest issue. I would like to compare the two harnesses and make sure that everything that has been noted can be transfere over as well to verify from the wire schematic that everything is where it should be.

Some of the questions I have so far are:

Pull the wiring from one side of the wall or the other?

Keep pulling wiring our from under the dash to see if there is any other connections ?

Do I continue to unwrap the covering tape until I find what I am looking for?

What is the best way in which to remove the wiring for the emissions/EGR without affecting the entire electrical system.

How do I install the newer harnes? Are there any tricks of the trade?

Should I do the wiring last after everything else is reinstalled or should it go first?

I am greatly apprehensive about moving forward for fear I am going to do create a bigger rats nest than what I found under the fuse box.

Where should I start?

My Sincerest Appreciation to those who can help me,

Justin

'75 02

Lola

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I'm not sure but I think the largest concentration of wire is at the

fuse box. At least on the '76. Just mock out the branches. One for

the lights, horn, A/C, one for the starter, temp sensors, one for the mag valves along the firewall, and a long one for the dist. points, and coil. The rest goesl through the firewall and under the dash. The multi-pin

connectors for the column switches and relays and instrumentation can be turned and the ends jammed through the holes in the FW. Never done it but that's about all I know! Good luck.

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I believe they installed harness opposite of how your are trying. they probally installed gas sender and tailights first, seatbelt alarm etc through holes in firewall. I don't think wiring at fuse box will fit through firewall.

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I believe they installed harness opposite of how your are trying. they probally installed gas sender and tailights first, seatbelt alarm etc through holes in firewall. I don't think wiring at fuse box will fit through firewall.

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Don't cut your harness!

I wrote this a while ago when I first joined the board. This should help with removal. More answers to your other questions coming in a bit.

...

Its probably a good idea to go ahead and cut the 2 firewall grommets. You'll want to be replacing those anyways.

There are 2 wiring harnesses in a 2002. You'll have the "Engine harness" and the "Body Harness" - these are joined together near the steering column on the body side of the firewall by three plugs (2 round 5-pin, and one square 3-pin, if I remember correctly) Make sure to disconnect these, as you'lll be pulling the body and engine harnesses out separately.

For the body harness, start at the rear with the Taillights and fuel sending lines, and pull all of that into the cabin through the hole over the left rear wheel. After that, disconnect all the seatbelt wiring (if your car has these, they are 2 sets of 2-pin plugs per seat, one large and one small) as well as the e-brake wiring. Pull all of this past the back seat bulkhead and out from under the driver's seat support, and leave it in the driver's footwell. (don't forget your defroster wiring too!)

If you rally want to get picky, you can lift the car up and disconnect the transmission wires, but that can be a pain in the ass. I just cut mine, and soldered new ends on later.

Pull the headliner down, along with the vinyl along the driver's A-pillar. Then disconnect your dome light, and run the wires out back through the roof to get them out. Its a good idea to either cut the spades off the end, or tape them up, as they can get caught in the roof panels sometimes. If you're not re-doing the headliner, cut the three wired coming down from the driver's a-pillar and leave enough leads to solder these back together later.

Start unplugging things under the dash:

- 2 plus on either side of the steering column

- large roud plug for gauges

- wiper & turn signal relays

- dash seatbelt warning light

- heaterbox

- passenger & driver door pin trigger

- cigarette lighter & headlights & defrost by gauges

- several ground wires

- 14ga wires @ ignition

Make sure you remember what goes where. Mark the ignition wires or take a picture before you disconnect them, so you know where they go later. This is where I cut my harness I was removing, since I added another harness in later. I left about 1/2" of each wire on the ignition so I knew what would go where later. There's a bunch of bent metal tabs that hold everything up against the firewall - make sure to get all of these out of the way, or you'll be tugging and swearing a lot. If there's a bunch of stereo wiring or jury-rigged foglamp crap in there, just leave it be for now. It will be easier to see what to cut out when its not stuffed in the car.

Don't worry about unplugging the heater box wires at the box itself (the 4 wires for three speeds and ground) these are attached to a different 2-pin white plug in the "body" harness of the car

Unscrew the doorpins and disconnect the wires from behind them. The passenger's side one is threaded up inside the dash. Cut the end off or tape it up so it, also, doesn't get caught.

Now go up under the hood and unscrew the fusebox. Disconnect everything from behind there (all colour-coded) and slide the connectors out of the oval hole one-by one. They won't all fit at the same time. Half of the wires and connections here go to the "body" harness and half to the "engine" harness. It should be easy to determine what goes where when you're digging through it.

There are also several wires that lead to random places such as the horn, washers, and distributor. Disconnect these and thread them back through into the cabin.

Also disconnect the grey plug that goes to your wipers. Thread this through the hole in the firewall.

Guide the fusebox plugs through the hole in the firewall last (again, one at a time - they need a good deal of room) towards the cabin, and you should now be done with the body harness!

The engine harness is much easier, especially if there's no engine in the car. Start from the front with the headlights and turn signals, and work your way back. Most things just slide off, and there arent really many tricky bits. your grommets from the headlights may still be good. If there are any grommets on this harness that are intact, leave them be. You'll be pulling this one out through the engine side of things, not the body.

There are a myriad of clips or bent metal tabs that hold things in place throughout the engine compartment. Remove these as you go along, but the bent tabs have a nasty habit of breaking. I just ground mine off and drilled the holes for the clips in their place.

Pull the three relays and voltage regulator off near the battery, and disconnect the 3-pin voltage regulator plug at the alternator. there is also a larger thick red wire that goes here and into the harness. Disconnect that too. The rest of this harness is pretty self-explainatory. Just unplug and work your way back to the firewall. There are several grounds around all over the harness. Make sure to remove them all.

When you're done, pull the smaller amount of the wiring inside the cabin (Ignition wiring, tach, 3 plugs that go to the body harness, etc) through the firewall and back into the engine compartment. You are now done with the engine harness!

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What is the best way in which to remove the wiring for the emissions/EGR without affecting the entire electrical system.

This should all be modular and not wrapped into the factory harness at all. Most of it is covered in blue (now faded to bluish-grayish-green) wire tubing. There are a couple of relays mounted above the brake booster bracket on the driver's side of the firewall. I believe you have to run a lead from the fusebox to the coil (+) side, but I'm unsure what fuse to run it from. Someone else could probably answer that better than I could, its been ages since I did it.

How do I install the newer harnes? Are there any tricks of the trade?

Make sure you buy new grommets for everything, even if they're generic auto store ones. You'll be thankful in the long run. Test things constantly and never tie down any wires with screw-down ties, you risk nicking a wire and grounding something out. Try to emulate the factory positioning and place all grounds at the same point if possible. Scrape paint away from ground connections. Clean all old connections with electrical contact cleaner, but replace them if you can.

Should I do the wiring last after everything else is reinstalled or should it go first?

I did mine first. If you're making a custom harness its easier to match the length of the wiring to your components (I did this for my MSII install) but for factory stuff you're probably okay putting the wiring in first unless you're planning on moving things around a lot.

I am greatly apprehensive about moving forward for fear I am going to do create a bigger rats nest than what I found under the fuse box.

Where should I start?

First, place zip-ties at all the junctions on the harness (where bundles of wires split off) and about every 10-12" along the harness itself. This will help it keep its shape, since you're going to want to cut off all the old wire wrap. Cut off the wrap, then leave the whole thing in a bucket of soapy water for about a day or so to get all the grease out of the connections. clean and dry as needed (it will still be pretty dirty after you do this, but its better than it was!)

Get a good multimeter, a paint pen or sharpie, your wiring schematic, and a lot of free time. Start at one circuit and test continuity and resistance from one side of the circuit to the other (say, headlight switch to fusebox, then fusebox to headlight plugs) then mark off the pins you've tested as "good" as you go along. do this for EVERY CIRCUIT. I know this sounds like overkill, but if you wrap up a non-tested harness and have to figure out why your left highbeam won't work, you'll be happy you did this.

If there's a break in the continuity, clean the pins and test again. If theres still nothing, start tracing the wires to find the break, and replace as necessary.

I find that a lot of the wiring under the hood gets very brittle, especially the alternator wiring, starter wiring and the ground leads, probably from all the amperage flowing through them.

Let me know if you need anything else, I'm happy to lend a hand (but no, don't mail me your harness!)

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