testing electrical
Thread Starter
Melting Slicks
Joined: Oct 2006
Posts: 2,193
Likes: 156
From: Navarre FL
testing electrical
ok guys and gals, im not the best with electrical so hopefully someone can help me figure this out. I have the engine and tranny removed (actually, they were never in it when I got it) for a rebuild. I have the majority of the project just about done but I have a few places here and there where I end up waiting on bits and pieces to arrive. Id like to try and start checking out electrical systems while I wait. Is there any way to get power to the main harness without having the starter and alt hooked up? I know I can trace the circuit and check continuity, but I would like to be able to turn things on here and there if possible...can this be done?
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
The main battery cable connects to the main engine harness at the starter and powers everything from there.
You can clamp the connections together and power it up that way. Be careful, it will make the alternator wire hot, tape it up.
You can clamp the connections together and power it up that way. Be careful, it will make the alternator wire hot, tape it up.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
All you need to do is connect the 2 red wires at the starter to the battery cable with a 3/8 bolt, insulate that with some tape, then insulate the output wire from the alternator. There's also a ground wire that comes out of the starter harness- hook it to the frame or anything that will give it a ground. Everything should work.
Thread Starter
Melting Slicks
Joined: Oct 2006
Posts: 2,193
Likes: 156
From: Navarre FL
what type of wires am I looking for at the starter? I just did a quick look out there and Im not seeing it right away. Im assuming they are a larger guage wire? This car was a bit of a mess when I took over so I guess I need help in identifying the main engine harness.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
In the harness that runs to the starter, there are 3 wires with larger ends- 2 are the power that feeds the car thru the fusible links, and the 3rd one is the ground. There are also either 1 or 2 wires that have small terminals on the ends- one of those is the "start", usually purple or purple/white and 10ga(?) that engages the starter, and the other runs to the + side of the coil for starting.
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Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,112
From: Crossville TN
Since you are asking for advice, I would advise you to check ALL of the circuits for correct continuity (that means that each wire is connected at each line where it is supposed to be AND it is NOT connected to any others) before you put any power to the system. Then, you can do a power check, if you want, but it would be unnecessary if all circuits are correct.
If you DO NOT check the wiring when powered up, the only [significant] downside is that you could have a poorly connected circuit which can not pass adequate current through it. This [minor] risk can be abated by doing a careful visual check of all terminations/connections in the harness.
If you DO NOT check the wiring when powered up, the only [significant] downside is that you could have a poorly connected circuit which can not pass adequate current through it. This [minor] risk can be abated by doing a careful visual check of all terminations/connections in the harness.
Thread Starter
Melting Slicks
Joined: Oct 2006
Posts: 2,193
Likes: 156
From: Navarre FL
Thanks for the inut everyone. I havnt had a chance to put power to it et, but the piece I was missing is that the starter harness extension is missing from my car. That is what really had me scratching my hear. Luckily I got a good deal on a box of used harnesses off fleabay a while back and there is a good one in that. That was one of those purchases I got "just because" and it was a really good deal, I figured if ny of mine were in bad shape I would replace them with those *** I went along...looks like it just paid for itself.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Check all the terminals in both sides of the starter harness. If they appear just a little dirty, clean them up or fight with them later. Corrosion is a really good insulator and causes resistance. Resistance makes heat- and that cooks the plastic connector.
Thread Starter
Melting Slicks
Joined: Oct 2006
Posts: 2,193
Likes: 156
From: Navarre FL
Thanks, Ill check all the plugs this week as well.
After a visual inspection to secure any loose wires I put power to it and so far so good. Looks like I need new flashers and need to check the headlight plugs for sure, no power to the stereo or hvac controls either. There are some spliced wires here and there that Im going to have fun chasing down in the wiring diagram, but having power makes it easier. Anyone know what the plug with all white wires on the steering column is?
After a visual inspection to secure any loose wires I put power to it and so far so good. Looks like I need new flashers and need to check the headlight plugs for sure, no power to the stereo or hvac controls either. There are some spliced wires here and there that Im going to have fun chasing down in the wiring diagram, but having power makes it easier. Anyone know what the plug with all white wires on the steering column is?
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,112
From: Crossville TN
Do you have fiber-optic system (68-71)? If so, there are some [little known] black plastic tubing pieces that fit behind each of the headlamps just inside the electric connectors. Those are there to focus what little light comes from the 'sealing nipple' on the rear of each bulb into the F/O strand that is imbedded in the connector. They also prevent stray light from entering the F/O strand.
Thread Starter
Melting Slicks
Joined: Oct 2006
Posts: 2,193
Likes: 156
From: Navarre FL
No fiber optics...78 model.
Since it is somewhat related...I also replaced the printed circuit for the speedo/tach. I noticed that the new one seems to be missing an opening for a light bulb. Doing a little looking around other vendors, it seems all of the neww ones are missing this cutout, at the bottom of the guage. What goes there and why is it missing on the new cicuit boards?
Since it is somewhat related...I also replaced the printed circuit for the speedo/tach. I noticed that the new one seems to be missing an opening for a light bulb. Doing a little looking around other vendors, it seems all of the neww ones are missing this cutout, at the bottom of the guage. What goes there and why is it missing on the new cicuit boards?
