New Wiring Harness Options

[TroyCo]

So I had what appeared to be the dreaded ammeter short out/ melt/ fire to my engine harness and bulkhead. What is the best way to go for replacing those bulkheads/ harnesses? I noticed Painless has a kit, but not sure of the best way to go, factory repops or a more modern designed kit?

 

[LocuMob]

Evans wiring can make you a new harness, you may need to send your harness in, as they may need to reuse some of the connections.

Or be like me and part out a bunch of cars so you have extras. Still best to have new wiring, but I have originals to use as a pattern if I decide to make my own, or send to the Evans.

 

[CBODY67]

The Painless kits are universal in nature. In other words, "cut to fit" rather than "plug 'n play". Good quality stuff, just not a direct plug-in situation for an OEM application.

CBODY67

 

[Ross Wooldridge]

I hear lotz of good things recently about Bill and Rose Evans, but it can be expensive.

 

[TroyCo]

I was looking at the Painless harness, but I'm not sure I want to wire the entire car. I need to investigate to see if any interior wires were damaged as well. So far the bulkhead and the engine harness appear to be the only casualties. The ammeter is definitely getting 86'd, I can tell you that. Is it best to bypass the rest of it, or gut it altogether?

 

[Ross Wooldridge]

Just bypass it. That way the main power wiring that would have run to it can safely remain in the engine bay, and leave the gauge in the dash unconnected. Protect it with a new fusible link - buy a roll of 14 AWG fusible link wire (cheap at Napa), and make your own.

Search ammeter bypass here on the site for instructions - but basically you're just joining the red and black wires together as if they were at the amp gauge. Just do it in the engine compartment for safety.

 

[Mike66Chryslers]

If your only problem is the main power feed wires, I recommend just replacing those. Look up the "MAD conversion". Lots of message threads here discussing it.

Basically you run a new heavier-gauge wire from the BAT post on your alternator over to the big stud on your starter relay, which doubles as the power distribution point for the entire car. Then another wire from the relay stud, through a hole in the firewall, to supply power to the interior. Install fusible links inline in both wires and a grommet where it passes through the firewall. Wire-wire connections should be crimped with non-insulated butt connectors with dual-wall heat-shrink over them.

 

[Gerald Morris]

If your only problem is the main power feed wires, ....

Wire-wire connections should be crimped with non-insulated butt connectors with dual-wall heat-shrink over them.

SOME wire splices need to be twisted, soldered, THEN double insulated w heat-shrink and rubber tape. For 90% of the splices though, your suggestion works well enough. I like 3M Scotchlok wire nuts for wire joints that might be revisited. I DON'T recommend any lesser wirenuts though, at all.

 

[Mike66Chryslers]

SOME wire splices need to be twisted, soldered, THEN double insulated w heat-shrink and rubber tape. For 90% of the splices though, your suggestion works well enough. I like 3M Scotchlok wire nuts for wire joints that might be revisited. I DON'T recommend any lesser wirenuts though, at all.

I used to solder automotive electrical connections, but after a lengthy discussion with Bill Mounteer on the relative pros and cons, I no longer believe that automotive wiring should be soldered. And IMO wire nuts have no place in automotive use ever!

 

[Ross Wooldridge]

I agree in a general sense @Mike66Chryslers , but note that there soldered unions in the dash harness, which the factory calls welds. Perhaps there's a difference. Regardless, they're done without flux, which is the problem, since it can contain acid, and it can make for problems down the road (pun intended). Soldering at a crimp connection is generally a no-no, due to the flux issue.

I agree that wire nuts such as the "pinch and snap" type are no good, but a proper fully insulated wiring connector such as a small terminal block with cap is OK, in my thinking, and hence, done right, a good nut and bolt union with proper ring ternimals and lockwashers under nuts, with the whole shebang properly insulted should suffice.

My wagon had two such "previous owner" unions under the dash, and I've owned it 25 years, and who knows how long they'd been there before, but they were properly done and hadn't budged or corroded.

 

[jake]

I am in the process of rewiring my car now and went with this kit. A little overkill, but well built and heavy gauge wire. I am not a purist so not having correct wire colors does not matter to me. I just want the piece of mind that it is not going to burn down on me.
Highway 22 Plus Universal Wiring System

 

[Big_John]

So I had what appeared to be the dreaded ammeter short out/ melt/ fire to my engine harness and bulkhead. What is the best way to go for replacing those bulkheads/ harnesses? I noticed Painless has a kit, but not sure of the best way to go, factory repops or a more modern designed kit?

From what I've seen, the Painless kits are named wrong.

They basically convert your wiring harness to a GM style because the rest of the world seems to think that it's better, but it's just not. Unless you are really good at doing electrical work, I'd stay away from them. Probably decent quality for their price point, but it's still just a bunch of wire and a fuse block with some instructions. If you've wired a car before, you'd probably be OK. From what I've seen the generic harnesses don't have all the accessories either, so now you have to do patch in your old wiring or make new. IMHO, more work than it's worth.

If the existing harness can be repaired, that's a good way to go, but replacements from the vendors listed is probably the best at this point. Many times I hear of problems like yours and they can often be traced to some bad aftermarket add-ons, bad replacement wiring, loose/bad connections, worn insulation, and/or someone has deleted the fusible links that protect the wiring. A new, correct harness will stop that nonsense from happening again. If you'd like, the ammeter can be bypassed easily under the hood, but again, the proper protection of a fusible link has to be added.

That's my two cents.

 

[TroyCo]

So I've had time this weekend to check things out, the harness had only one wire that burned up, going to the transmission harness, strangely enough. The bulkhead connector is melted where the main power wire passes through, so that's getting replaced as well as the other harness connectors. I decided to replace the entire engine harness with a new one that has the electronic ignition wiring added to it. The old wiring had all that stuff crudely spliced in, so it would have inevitably have been a failure point for sure. Ammeter bypass is also underway.

 

[Mike66Chryslers]

I agree in a general sense @Mike66Chryslers , but note that there soldered unions in the dash harness, which the factory calls welds. Perhaps there's a difference. Regardless, they're done without flux, which is the problem, since it can contain acid, and it can make for problems down the road (pun intended). Soldering at a crimp connection is generally a no-no, due to the flux issue.

I agree that wire nuts such as the "pinch and snap" type are no good, but a proper fully insulated wiring connector such as a small terminal block with cap is OK, in my thinking, and hence, done right, a good nut and bolt union with proper ring ternimals and lockwashers under nuts, with the whole shebang properly insulted should suffice.

My wagon had two such "previous owner" unions under the dash, and I've owned it 25 years, and who knows how long they'd been there before, but they were properly done and hadn't budged or corroded.

By "wire nuts" I'm referring to the type commonly used in household wiring, which I'm pretty sure is what @Gerald Morris is referring to as well. Save those for household wiring.

I've never picked apart a wiring harness to find the factory welded connections, since they rarely fail and aren't a cause for concern in our cars. To my understanding:
- They are actually welded connections where the wires are pressed together and heated until they melt together themselves, not soldered. These would be done in a factory, likely with equipment that generates localized heat quickly, so the surrounding wire insulation isn't burned.
- They are only used in the interior behind the dashboard, not underhood, so relatively protected from the elements.
- They are wrapped in a copious amount or harness tape, and attached at various points behind the dashboard, so not subject to much vibration.

In addition to the flux, soldering heats-up the insulation making it hard and brittle close to the connection, and makes a very rigid spot in the wiring which cannot flex. If there is any vibration in the wire, it is more likely to break beside the soldered joint.

OTOH, a crimped connection with dual-wall heat-shrink is electrically and mechanically sound, well-sealed against the elements and is slightly flexible in case of vibration.

In a nutshell, those are the pros and cons that convinced me that crimped and heatshrinked connections are the best way to make automotive wire splices. I'm not talking about connectors or terminal blocks which may need to be disconnected, only splices where two wires need to be joined together (hopefully) permanently.

 

[TroyCo]

From what I've seen, the Painless kits are named wrong.

They basically convert your wiring harness to a GM style because the rest of the world seems to think that it's better, but it's just not. Unless you are really good at doing electrical work, I'd stay away from them. Probably decent quality for their price point, but it's still just a bunch of wire and a fuse block with some instructions. If you've wired a car before, you'd probably be OK. From what I've seen the generic harnesses don't have all the accessories either, so now you have to do patch in your old wiring or make new. IMHO, more work than it's worth.

If the existing harness can be repaired, that's a good way to go, but replacements from the vendors listed is probably the best at this point. Many times I hear of problems like yours and they can often be traced to some bad aftermarket add-ons, bad replacement wiring, loose/bad connections, worn insulation, and/or someone has deleted the fusible links that protect the wiring. A new, correct harness will stop that nonsense from happening again. If you'd like, the ammeter can be bypassed easily under the hood, but again, the proper protection of a fusible link has to be added.

That's my two cents.

Despite the engine harness being what it was, the rest of the wiring in the car is largely unmolested. Which is fortunate. The only add-ons being the tach I added and a 3 gauge set I've yet to install, all of which have no wiring spliced into the original harness. I hate wiring, so whenever I can find something plug and play (preferably stock) I go for it. Also, the fusible link on the other harness was intact. These among other reasons are why I always add a quick disconnect on the battery and carry an extinguisher in any old car I buy.

 

[Ross Wooldridge]

By "wire nuts" I'm referring to the type commonly used in household wiring, which I'm pretty sure is what @Gerald Morris is referring to as well. Save those for household wiring.

I've never picked apart a wiring harness to find the factory welded connections, since they rarely fail and aren't a cause for concern in our cars. To my understanding:
- They are actually welded connections where the wires are pressed together and heated until they melt together themselves, not soldered. These would be done in a factory, likely with equipment that generates localized heat quickly, so the surrounding wire insulation isn't burned.
- They are only used in the interior behind the dashboard, not underhood, so relatively protected from the elements.
- They are wrapped in a copious amount or harness tape, and attached at various points behind the dashboard, so not subject to much vibration.

I have picked them apart before, and all you say is correct, but there is a solder medium in there as well. Since the heat is high as you surmise, that probably does away with the need for flux. Not sure how that works, but there is definitely solder of some kind there.

In addition to the flux, soldering heats-up the insulation making it hard and brittle close to the connection, and makes a very rigid spot in the wiring which cannot flex. If there is any vibration in the wire, it is more likely to break beside the soldered joint.

OTOH, a crimped connection with dual-wall heat-shrink is electrically and mechanically sound, well-sealed against the elements and is slightly flexible in case of vibration.

In a nutshell, those are the pros and cons that convinced me that crimped and heatshrinked connections are the best way to make automotive wire splices. I'm not talking about connectors or terminal blocks which may need to be disconnected, only splices where two wires need to be joined together (hopefully) permanently.

I agree, and you outlined the issues much better that I could have.

 

['66 Fury I]

Soldering without flux is, at least in practical terms, impossible. The flux allows the solder to flow into the joint and adhere to the material. The proper flux for electrical soldering is "rosin" (aka "resin"), which is made from pine pitch. Other fluxes will cause corrosion and compromise the connection. Heat shrink can provide vibration and strain relief. I have soldered connections that have been in service for 30 years- some underhood and uninsulated. LC
PS the word "flux" by definition, means "to flow".

 

[Ross Wooldridge]

Agreed - and this where I think the high heat element plays a role in the factory wire "welds" compared to what's available to the DIYr, and becomes as you say, impractical.

 

[Gerald Morris]

To my knowledge, there was but one weld in the old C bodies, in the power/ammeter loop at a junction of 3 conductors. Welded copper oft is "brazed" together with, a brass medium. I suspect the factory weld though might have been a true weld. I don't know and cut it out to re-arrange the junction, with no harm 5 years ago.

3M wire nuts are rated for commercial, industrial and yes, automotive use, but VERY FEW OTHERS are, and not recommended or used by myself. If the joint is permanent, I usually solder it if its not practical to terminate. I use split bolts with rubber and friction tape for fusible links as that allows them to be changed out easily in situ if needed. This protocol is deemed adequate for industrial high voltage wiring, but it is bulky.

I should score some of the heat shrink crimp terminals and butt splices too, as there are at times places for these, and they're certainly better than vinyl. If a terminal needs serious protection, I heat shrink them as a rule. Good heat shrink has some mechanical strength, though I'd not recommend RELYING on that.

 

[TroyCo]

So here's what I'll be up to while I'm waiting for a new engine harness: I get to re-pin the bulkhead and add these new terminals to the other harnesses. Fortunately it's not a lot of wires on this old car. Thanks to National Mo-Parts for the goodies.