Guys, I need some advice from the ever wise C3 community. I have several wiring gremlins (thanks bubba) that I hope to eliminate through the replacement of my car's complete wiring harness. I also want to pull my engine to rebuild it and detail the engine compartment while it's out. My question is.... should I replace the wiring harness before I pull the engine to make sure everything works or should I replace it after I pull the engine when I can easily reach everything? My instincts tell me to replace the wiring with the engine in so I can make 100% sure everything works then pull the engine. I'm sure replacing the wiring will be easier with the engine out but I'm a bit worried about not immediately knowing that I've got it right through real time testing. What are the group's thoughts?

 

I did mine with the engine in, it's actually very easy.

Use only LectricLimited harnesses with the Doc Rebuild wiring chart.

http://www.lectriclimited.com/

 

I did mine with the engine out. 45 min for the engine and another 45 for the headlamp harness. That includes beer time.
Either way will be easy. The only part that took me time was going around the wiper motor because I had to loosen it up.

Just put in each new wire as you take an old one out so you don't have to go back and guess where something was. VERY easy.

 

scottw,

Did you rewire you're whole car? I'm also wondering since I plan to replace all the wiring, is there a logical order I should work in? Front to rear? Inside out?

 

I only did the front two. You have to disconnect the bolt in the engine compartment that releases the engine and headlamp harnesses in order to get the fuse box and main wiring harness off. (along with the two bolts on the corners of the fuse box on the inside of the car)

I haven't looked at doing the main and rear harness. Not sure it really matters which one you do first though.
When I did mine, I started at the fuse box connection and took a wire off the old harness and put the new one on at the same time. That way I didn't lose track of any wires. I don't think that is doable with the main wiring harness.

Nice looking car by the way.

 

After engine removal...of course. But, label every disconnected wire--both leads. Then, transfer the labels to the new wiring. That way, you will be able to easily note any wires that could be "different" on either the new harness or the old one. You may also need to save/swap some of the original connectors (hopefully not...they should be pretty brittle by now).

Good luck!

 

Replacing the harness then removing the engine and detailing the engine compartment is bass ackwards. How will you clean and paint the areas that the harness runs?

The assembly of these (any) cars is designed so that the guys on the assembly line with grade 8 educations can put them together. There are no two identical plugs used anywhere within vicinity of one another in the harness, if at all. There are very few connections that have a simple eye rather than a block connector and all of those on a black wire are grounds. The others go on the nearest live terminal (alt and starter). There are some flag type terminals near the horn relay and they go, you guessed it, on the horn relay.

It's pretty much plug and play.


Steve g

 

Steve2147 is correct....IF you 'assume' that all the wiring and connectors are the same as they left the factory. But, after 40 years, how good is that 'assumption'? Hence, the need to ID your connections. The last thing you want to happen is to yank all the wiring apart, then start reconnecting...only to find that "stuff" doesn't hook up right. Then, where are you????

 

Not in my shop. 45 minutes and first beer looking at the engine and considering pulling it.

Congratulatory beer after the engine is out and on the stand.

Third beer only after a trip into the house for the Necessary (affects of two beers) then getting the gook off the harness bolt, getting the bolt out, and unplugging the forward lamp and engine harnesses.

Job-Well-Done beer after the harnesses are out and another trip into the house.

 

I disagree. If the engine compartment isn't as it left the factory you are not going to bubba your new harness to fit what was done. You are going to debubbatise the engine compartment and make it fit your new harness. Nothing wrong with labeling all the connectors but in my opinion is redundant. By design the plug blocks will only fit one place in one direction. If you have a plug left over with nothing to plug it into all the labeling won't help you identify the missing part.

There are only 4 places you will find connections other than grounds that do not use a modular plug. The starter has two small eye wires, the purple one always goes on the stud nearest the block. The coil wire has a flag terminal, will be the only one exiting the harness near the coil and always goes to the + terminal on the coil. The alternator has one large red wire with an eye for the batt connection and the horn relay has is a junction block for power wires and have flag connectors. All the wires in the light harness except grounds are modular plugs. Same with the AC harness.

What you really need is an assembly manual. This will not only clear up any questions about connections, but will also give you the correct routing and clamping of the harness, something that observing the old harness won't tell you.It will also show you the correct bolts to use for your ground wires which Bubba may not have used.

If the op's car has the fibre optic light monitors you need to know that to replace the light harness involves disassembly of the dash and centre console to pull the optic tubes out.

We all have our preferred way of doing things. My preference with respect to the engine harness is to start the harness installation at the starter with the engine out and starter off. I install the wires to the solenoid and through the clip on the solenoid then install the starter to the engine which connects the ground wire (69) on the starter mount bolt. I then connect the coil wire and lay the harness on top of the engine and complete the installation once the engine is in (or the body back on). This way the only connection I have to do from under the car for is the batt cable to solenoid.

My observation has been that the more you can replicate the original assembly sequence, the easier things go together. It's designed that way. A lot of time is spent by engineers determining what order things should go together to minimize assembly line time. Even if the time isn't important to you it generally helps avoid those frustrating bolts that you can only move 1/16th of a turn at a time.

Each to his own, but that's my preferred method.

Steve g

 

We've shared our perspectives...the OP will do what he will.

 

I dont think there's a logical order. I did engine, front and then rear. The dash is last only because it's the most difficult.

 

Good stuff. Thanks guys for your input. Hope to be off and running on the project soon.

 

I replaced all the wiring in my '73 from front to rear. I suggest that you take lots of digital photos for future reference. Bubba didn't get to everything. Also, like was previously suggested, get both of the pictorial posters from Dr. Rebuild. The new wiring will be a bit of a puzzle at first, but these posters will make it oh-so-ez!

PM me with your email address and I'll send you some photos if you need.

Good luck,
John

 

JohnRR
I sure could use those pictures if you still have them. I do not know how to pm you.

 

I sent you a PM. Or you can call me....

John
7one7nine2six71six3

 

I just sent you a PM with my email address. Send me your and I'll email you a bunch of pics.

John