Electrical Help

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pacuda59

pacuda59

pacuda59
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Can someone recommend a good book on automotive electrical systems for the beginner?

I'm trying to work out the electrical bugs in a 69 Cuda and have a lot more enthusiasm than experience.

Thanks
 
A "basic book" may not be all that much help. That's because every manufacturer has their own special way of labeling wiring connectors, etc. AND Mopar does a few things different than some others. The starting circuit is kind of a trick, and so is the wiper motor switching.


Very FIRST thing to do is get on eBay or other sellers and buy yourself a DIGITAL full service manual, for the reason that if you have questions, you can post screenshots of certain sections here for discussion, or you can blow up sections and print them for easy reading when chasing a problem.


................ and if you have the bucks, I'd get a paper reprint, too. Then ask questions here.

A lot of your questions are going to depend on..................

Do you have the factory harness?

For restoration, do you want to KEEP a factory style harness?

Or are you looking for the day when you rewire the car with an aftermarket harness?

MANY MANY of the bugs in these old girls are coming down to a few specific areas:

More and more guys find problems with the firewall connector, or bulkhead connector, where the major wiring goes through the firewall to the interior. These are getting old, corroded, and damaged from too much heat.

Original charging systems cannot put up with modern add --ons, like halogen headlights, stereo, fuel pumps, electric fans

Many of us "threw in the towel" and bypassed the ammeter, went to a voltmeter

Installing headlight relays, and other relays to run ignition, fuel pump, etc is a big help to relieve strain on the old harness and the bulkhead connector.

PLEASE be SURE to ask questions
 
To begin with, my background is digital hardware/software engineering and design. So I'm not trying to be a jerk or a know-it-all and my comment isn't meant to contradict anyone, but, older automotive electrical systems are not digital, I'm just trying to get you in the right direction. I know this sounds like I'm simplifying things, but, wiring/circuitry is only battery and ground. So given that, you really need the factory manual for wiring. Then find the system that isn't working. Begin there by tracing back towards the battery or ground that makes the item work. For instance, you're trying to figure out why a new and working light bulb doesn't light (key word working, a new bulb can be bad). If you have battery going into the bulb (and out the other side, means it's a good bulb) and it still doesn't light, then trace towards the ground and find where the ground is broken. If the bulb has no battery, then begin at the bulb, and trace back through each termination point to see where you see battery. Too bad you don't live near me and we could spend a few hours tracing a couple of problems. Once you get the idea on how to read the wiring diagram (and color codes) and then trace the circuit backwards and forwards through each termination and bulkhead you'll be on your way to a new career in frustration. I've spend hours on just one problem, so keep at it and use logic. Walk away when you get frustrated and come back later with a clear mind.

If you have just installed a new wiring harness, do not make the mistake that it perfect. I've found wiring issues with brand new harnesses. Use an ohm meter to make sure end-to-end continuity is correct. I once had a wire broken in the middle of a new harness and had to run another lead.
 
GT340 said:
.......................older automotive electrical systems are not digital,....................simplifying things, but, wiring/circuitry is only battery and ground.
Click to expand...


Sometimes, though, it's a little more complicated.

There ARE 'trick' situations where faulty circuits can cause unexpected results due to "backfeed."

For example, I don't remember the "trick" anymore, but someone on the www produced a procedure that they had evidently learned as kids. Left in the car, without keys, they wanted to listen to the radio. I believe it goes something like this:

You turn on the 4 way flashers, hold down the brake, and turn on the radio. These circuits all interact in such a way to backfeed the radio.

Other little tricks involve stuff like dual-filament bulbs that are internally shorted together. This causes stuff like a turn signal will flash all 4 lamps, and turning on the park lights either blows the fuse, or lights all 4 lamps, and then the turn signals won't flash.

THE BIGGEST problem I keep running into with guys cars are the BULKHEAD CONNECTOR, VOLTAGE DROP in the ignition harness (along with headlights) and poor grounds due to rust.

Secondarily, switches and connectors get old, as do the fuse box clips and connections.

An of course in this day and age we ALL think (or maybe do) need a larger alternator

TRUE story. Back in the days "we all" were using 4537's (landing lights) on our 4x4's (AND my RR!!) a guy I knew bought a pair, mounted to the front bumper of his 60's Ferd pick'emup. NO LIGHTS. He finally came into the store, and I went out with a test lamp. The front BUMPER which was bolted directly to the frame, was NOT grounded to the frame due to rust!!!
 
Wow,thanks for all the detailed information!

I picked up the Cuda in November and haven't done too much over the winter. I've decided this summer will be 'electrical summer' dedicated to finding learning and fixing multiple problems.

Among those problems.....

Interior under dash light
Install Map light switch
Fix trunk light.
Install vintage radio
Fix Temp and fuel gauges.

I've recently invested in a multimeter and have figures out how to test bulbs and switches. After that, I'm lost.....
 
67Dart273 said:
Sometimes, though, it's a little more complicated.

There ARE 'trick' situations where faulty circuits can cause unexpected results due to "backfeed."
Click to expand...

No kidding. Just in my Duster schematics there are many common sources of battery. Recently I had quite a time with a blown fuseable link that took way too long to find due to me not paying attention to the original problem and assuming that I was correct in the direction I took.

And, you're right, a high majority of problems can be found in the older corroded connections in the bulkhead connectors.

When I restored my car I stripped it down to bare metal shell and had it painted. With your experience in automotive wiring you know what a pain it was with all the grounds that I connected on the body due to painting the car. It was a real education in properly grounding a cars wiring system. When you build a new engine and paint it, be sure to properly sand all the grounding points on the engine to bare metal or you will experience some grounding problems on the few ground connections needed on your engine.
 
shout if can help. rewired my 68 cuda from scratch, made a rough diagram of what i needed and made my own loom up,you gotta break it down into circuits and not look and the whole picture! basic voltmeter a must, plenty of help on here, regards nathan, wales uk
 
pacuda59 said:
Wow,thanks for all the detailed information!

I picked up the Cuda in November and haven't done too much over the winter. I've decided this summer will be 'electrical summer' dedicated to finding learning and fixing multiple problems.

Among those problems.....

Interior under dash light
Install Map light switch
Fix trunk light.
Install vintage radio
Fix Temp and fuel gauges.

I've recently invested in a multimeter and have figures out how to test bulbs and switches. After that, I'm lost.....
Click to expand...
fuel guage has to be a matched ohmage as that of your sender in tank, my original one in dash was poo, i went autometer i think.another prob i had was the fuel pipe from sender in tank was a source of an earth from the electrical sender in tank,ie had to have a decent earth path, this had given me probs,most problems <as somone mentioned> are crusty earth points to car body and poor connections, these get hot and melt etc.some of my wiring cables had fried halfway through and looked ok each end, even gave continuity but would not like any real current going down there,also scotchblocks,twisted joints, my bulkhead connections fried but them its had 40 years of crap british weather.
 
I recommend a book by Jim Horner, Automotive Electrical Handbook. It is an HPbook ISBN - 0-89586-238-7. I bought the book because I met Jim at a car show and he was interesting to talk to. So I found his book. It has plenty of pictures and schematics about all the various electrical systems on a vehicle. It is a good resource for doing from scratch wiring for street rods and kitcars, or doing maintenance.
 
I recommend you email Rick Ehrenberg at Mopar Action. Ask for a list of relevant back issues and hunt them down.

They'll cover not only theory but practical operation and much-needed mods. He can recommend several good books as well.
 
First; grounds, you can't put enough redundant grounds in these cars. Bypass that dam ammeter, it doesn't tell you antyhing to begin with. I'm charging(how much? I'm sucking too much voltage into the dash. Mad bypass.

Then transister volt reg. Then ohm those dam grounds again.

That 4 way flasher is tied into your turn signals, and will cause pain. Again, rear light grounds will cause insanity.

And the turn signal switch; just a touch of figuring that thing out, after several hackers have been there. Also, that switch- don't tighten the screws- put some locktite on them. Don't crank them down.
 
You turn on the 4 way flashers, hold down the brake, and turn on the radio. These circuits all interact in such a way to backfeed the radio
Click to expand...
.


That was me.
Just for old time sake I tried that trick out again on the Dart just now. It didn&#8217;t work. However, I have made several modifications to this car&#8217;s wiring harness adding relays, performing a Mad amp gage bypass and others. The back feed path has been plugged I guess.
 
Sorry for the delay....stomach flu!

Again, thanks for all of the great information! I've been scribbling notes as I go through this post by post.
I've downloaded the Beginners Guide to Automotive Wiring from one of 63 Dartman's links and it's been very helpful in understanding wiring diagrams.
My next challenge is to utilize the multimeter in my diagnosis of the problems I described above.

Stay tuned......
 
slantsixdan said:
Get the Peterson and Stockel books described in this thread.
Click to expand...


Get these books! I spent a total of $14 and that included shipping and handling for both books and they are both hardcover. Amazing amount of info in these books. Both are used but the condition of them is extremely good for books over 30 years old. Can't say enough about them.
 
When I upgraded with a Ron Francis Wire works system, they send out their catalogue.

Good information in the catalogue on the importance of grounds. Might be worth it to get one sent to you as well

And like already said Mad Electrical site has many good articles
 
i did the MAD ammeter bypass and rewired the charging system and installed a volt guage and now i know exactly what my charging system is doing and i love it.
 
Hey, pac, you have been handed a bunch of sources for basic/advanced information. But let me tell you, I have found the best source to be these guys here on this site. Learn the electrical theory first, then ask questions here. Have specific questions? Ask questions here. I learned aircraft electrical systems before I learned automotive electrical. Learn the basics; you can then apply that info to specific problems with DC circuits.

To quote the founder of Faber College, "Knowledge is good."
 
FISHBREATH said:
To quote the founder of Faber College, "Knowledge is good."
Click to expand...

Yabut Faber ALSO had to clean a dead horse out of Dean Wormer's office

animal-house-horse.jpg
 
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