New Wiring challenges

66furys

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I have not yet found an accurate wiring diagram.....have ordered yet another one.....assume that perhaps the correct 66 manual should have one. Not there yet. So, with my 55 year old classic, the shankers have been active on the wiring....you have never seen such a mess including melting, fire, open wire ends and household wire connectors.....so finally realized it will need complete overhaul. So, one of my recent interesting findings relates to how to protect the car with some type of fuse. I want to bypass the ammeter, and run the alternator feed direct to battery and will use a 70 amp maxi fuse. Then, I am thinking what size fuse to use for the car wiring. So, I begin by thinking about the headlites, that is my rant of the day. I have the dual headlites on the 66 fury, meaning there are six filaments on during high beam. So, six times about 60 watts give me round about 28 amps. So, I light up the circuit with a small 16 ga shunt with clips, and light up the four beams....voila it works. But, my question here is this. How in the world am I running 28 amps thru a small 16 ga wire for a minute or so, with no great heating problems. I want to protect my circuits with something like a 50 amp fuse for the ignition meaning the whole car. But, am not understanding this. If I tried this with a 120 or 240 volt circuit with this much current, I would burn the house down. I also run an EV charging cable with set up at 24 amps, and the 10 gauge wiring gets hot during charging. I am losing what hair I have left.
 

Rubatoguy

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Have you measured the current though the wire? Since 16ga wire is only rated for 13a, it would seem that there may be something off in your calculations. I always thought that the high beam and low beam filaments lit separately. FYI, it is common to add relays to headlights to provide more power to the lights and eliminate sending the headlight voltage though the switch. This link might be helpful: Daniel Stern Lighting Consultancy and Supply Lastly, you can safely have an amp meter in your car. Google SHUNT for more info.
 

live4theking

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You might save some of your hair by reaching out to these folks for some harnesses. They may have some that are not listed as well. EvansWiring.com : Product Catalog

Of course you can do the amp meter bypass, I would use the appropriate fuseable link for the gauge of wire you select. There is a great threads by @cbarge for doing this and adding relays for the headlights.
 

66furys

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Thanks for great comments guys. I did not measure, since my junk only goes to 10 amps, and my clamp on is AC. So, I am going by the six filaments that seem to avg about 60 watts, at this point. I have purchased the Painless wiring harness, and am fighting now to figure this out, before I begin the replacement. So, am reviewing things like the power in front harness for headlights, the tail harness and what is what, the connector for the turn signals, and on it goes. About half way thru my work before beginning the install. I did a simpler one on an MGA, with two fuses. I did use relays for the headlights and horn on that one......sooo the look at the current for these headlights. Thanks so far.
 

1970FuryConv

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Sorry about the melted wiring harness. Somebody had no clue.

I agree with the ammeter bypass. Usually, a fusible link is recommended, not a 70 amp fuse.
Also, after the bypass, the ammeter does not read properly, so a voltmeter is recommended.
I did the bypass in a 1970 Fury, but a 1966 Fury should be generally the same procedure.

I generally don't like aftermarket wiring harnesses. Calling someone like Murray Park or Wildcat Auto Wrecking would be the way I would go. I'd buy a clean factory wiring harness out of a junkyard car and repair as needed. Saves a lot of time over a universal wiring harness. However, more than one way to do anything. Best of luck.

Murray B. Park - Used and NOS Parts for Chrysler, Imperial, Dodge, Desoto, and Plymouth
Wildcat Auto Wrecking | Mopar Parts | Classic Car Dealer
 

jimmyessbee

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Wire gauge isn't just about amps. Volts play too. You can run much more amperage through a 16 gauge wire on 12 volts than 120. While 28a is more than should be run, I've got no doubt it would run a while. Probably get warm. And you probably don't have quite as much wattage as you think. Here's a link that shows wire gauge sizes for 12v including length of wire in calculations. Wire Size Guide Chart
 

CBODY67

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When Painless Wiring originated, it was mainly focused on street rods, where you did the complete wiring harness yourself, BUT used OEM-quality wire and connectors rather than "aftermarket" with variable quality and such. Unless they have a specific ready-made harness for what you need, it can be very challenging to use one of their kits to repkace a full factory harness, by observation. MUCH better to start with a good salvage yard harness from a similar car (make, model year, model, engine, etc.) that you can lay out and see where everything might go before doing any work to swap the harnesses.

One main difference between the aftermarket wiring kit and the factory harness is that the OEM harness can use one feed circuit to feed several things. Which means wiring junctions and such to make that happen.

Good luck,
CBODY67
 

66furys

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A couple of good points. I will have to think about power thru a wire vs current, which I have always thought was key to size. However, you are right that there is certainly more energy at the higher voltage. Hair hurting. Also, thanks for points on painless vice OEM. Not sure I ever make the right choice in life. I will say that my biggest challenge has been an accurate diagram. I have ordered another, since several I have found so far are bad, including from a major research firm for repairs. So, am battling with trying to go wire by wire and move along. But, appreciate the help.
 

CBODY67

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Personally, I have found the wiring schematic in the Chrysler factory service manual to be quite good. At first, it was "just a bunch of lines", but after I started to get farther into it, it was very informative on many levels. The only ones which might be better are the "full-size foldouts" that Ford used in the middle 1970s and so, where you laid the unfolded (several times unfolded for each harness!!) on the core support, side to side, and then started to see what went where.

ONE thing Ford tended to do back then, compared to GM and Chrysler, was only have about 6 wires through the bulkhead connector, THEN those wires branched out behind the instrument panel with inline fuses, wiring junctions, and circuit breakers "many places" behind the instrument panel. By comparison, GM and Chrysler had MANY wires in the bulkhead connector and also use it to contain several relays/circuit breakers in one neat location, with the multitude of colored and colored-trace wires going to their appointed locations. Each method has its plusses and minuses, by observation,.

In high school physics, I better understood volts and ohms, with the "Watts" measure of power or power consumption being on the fringes of my understanding. Except for the brightness of light bulbs. Volts and ohms I could readily measure with a meter and work from there. "Watts" was more abstract, to me. FWIW

Sometimes, by observation, we make things harder for ourselves in how we approach projects and problems. In many cases, we want to "start from ground zero, anew" rather than employ seemingly-easier approaches. In this case, starting with a universal-orientation Painless Wiring kit rather than a used, salvage yard (for the close-match harness) harness. BUT also being cognizant that seemingly minor differences in vehicle engine options can make a huge difference in the wiring (as in LA vs B/RB engines) under the hood.

In dealing with wiring harnesses (at the OEM level), it becomes evident that what we consdier to be "a harness", underhood harness in this situation, is really comprised of SEVERAL smaller harnesses. Forward lamps, wipers and washers, basic engine, charging system, air conditioning, and a few others. Each of them is usually specific to a particular model and model years, BUT very similar in most aspects. The parts books specify these things, but the FSM wiring schematics lay it out graphically.

Using the factory part numbers on these harnesses can be a starting point, BUT if there is ONE difference between two harnesses, it can be as minor as one harness having ONE wire which is longer/shorter for that one model year, due to a difference in how that ONE wire is routed. Or perhaps one harness has provisions (connectors and wires) for an accessory your car might not have. And these differences, no matter how small, will generate a different part number for the two harnesses.

For a time in the later 1990s, GM got smart with their light-duty pickups and built ONE harness that went everywhere (as to options on the vehicle). To add a keyless entry system, just plug in the transmitter/controller to the harness, in existing connectors. Program it and DONE! No additional wiring needed. Made things much easier at the dealership level!

We had one customer who added a keyless entry system to his new pickup, then complained that the power locks would not work. Our tech discovered that the aftermarket kit had caused the lock actuators to fail because of the way the kit wiring was done. So we replaced the actuators under warranty, repaired the wiring (unhooking his kit), and informed the customer that his kit had caused the failure. Then, it came back a few months later with the same situation. No warranty that time!

Just some thoughts, observations, and experiences,
CBODY67
 
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1970FuryConv

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A couple of good points. I will have to think about power thru a wire vs current, which I have always thought was key to size. However, you are right that there is certainly more energy at the higher voltage. Hair hurting. Also, thanks for points on painless vice OEM. Not sure I ever make the right choice in life. I will say that my biggest challenge has been an accurate diagram. I have ordered another, since several I have found so far are bad, including from a major research firm for repairs. So, am battling with trying to go wire by wire and move along. But, appreciate the help.
Did you download free service manual or wiring diagram from www.mymopar.com ?
 

Big_John

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I have the dual headlites on the 66 fury, meaning there are six filaments on during high beam.
On low beam bulb, there are two filaments as you know. When the low beams are selected only one filament works. IIRC, it's about 35 watts. When the high beams are selected, the other filament is lit.... Not both.

Some relay systems will light both filaments in the low beam bulb, but it's at the cost of life of the bulb.

The FSM is really the most reliable place for a wiring diagram. About every other offered is generic at best and some I've seen are just a bunch of colored lines. Hint: print out the wiring diagram and use high lighters to mark the wiring circuit(s) you are working on. Look at the wire numbers for the size.

I've never used one, but from talking to people and reading a lot of threads on here, Painless is the wrong name.
 

66furys

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I will review the free downloads.....I have become jaded about anything free lately, but will take another look. Thanks. I did take a second look at my headlight wiring.....black for low beam upper, and red for both up and down. But, I may have jumped the gun thinking that both filaments were on during high beam.....I think I am agreeing with you that there are only four. Thanks.
 

66furys

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So, a bit of an update on my attempt at a new harness. Have spent several days.....I am old, going thru the new to me diagrams from the service manual, and also from a classic wiring diagram....some help on big issues. I am finishing up my attempts to define exactly what wire colors and actual circuits exist in the car, OEM. Also, am going thru the new harness and both ohming and identifying what goes where, with labels for install. Finally coming together and most of my attempts to ohm the harness have been good, have had a few surprises, due to unclear manual and no wiring diagram for the new one. Want to be as sure as possible before begin install. I will clean off the OEM bulkhead connection block, and mount new fuse block on that. Will find a place to drill firewall for forward harnesses. But, after a lot of diagrams, a lot of notes on how things are connected, finally getting closer. I also want to get some of the classic loom material to cover the exposed wire harness, esp in engine bay. I may add a note in the electrical section on wire crimpers, that are crap IMO. I have about five types, and should design my own. Also, not sure anyone has some thoughts on the replacement of the turn signal connector. This thing only has about eight slots, but they used some strange type of terminals. I am not sure I can resurrect the connector as is, so would like to just replace with a similar spade type...easier for me than some of the pin types. I may just connect the seven wires separately with spades. Appears the spades on the main switches can be managed, and I will clean up the small pin connectors on both gauges and speedo. One final thought here....does anyone know where the voltage regulator for the two gauges is hidden....am guessing in the gauge cluster I sent out....but the new diagrams point this out.
 
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