Fried part of my wiring harness

[Mark1972]

My car is a 2 door 1970 Plymouth Satellite 318 auto. The engine is a 1969 318. I bought a new alternator for it a month ago, and asked for a 1969 unit because that's what the engine was. I figured better for mounting. It's a 2 field alternator. There is the battery wire, a dark green wire, and a dark blue wire. The latter are push on style. I was not aware that things changed in 1970 regarding wiring. So I hooked things back up as they were, with the dark blue wire closest to the battery connection, and the green wire further away. After getting all lights and stuff working the last 2 days, I finally turned the key in the ignition to the on position to check other accessories, and the dark blue wire melted immediately. It melted only between the alternator and the soldered splice. No other wires were effected. I have read that there is no difference between the two FLD's as to which wire goes where. But I've also read different. So I'm confused. The dark green wire went to the regulator along with a dark blue wire. The dark blue wire that burnt was spliced, with one going to the ignition ballast, and the other meeting the green wire in the regulator. Damn I hope I've explained that fairly clearly. No fuses blew. What could have possibly gone wrong?

 

[Xp29h]

Schematic -a
http://www.mymopar.com/downloads/1970/70BelvedereGTXSatelliteRoad RunnerA.JPG

Schematic -b
http://www.mymopar.com/downloads/1970/70BelvedereGTXSatelliteRoad RunnerB.JPG

These might help you out I hope. Follow your wires make sure they go where supposed to.
Good luck!

 

[Mark1972]

Well that's a better wiring schematic than I have. Thank you for that. According to that schem, it was wired correctly. I'll trace the rest of the wires in the morning and make sure everything is correct. Hopefully something will become obvious. I dont want to burn any more wires. Thanks again.

 

[Xp29h]

I might be way off, but take a look at your ammeter too and those wires. Those can cause a ton of issues!
Be slow and methodical as you look and search.

 

[72RoadrunnerGTX]

Ammeters don’t cause problems, lose or high resistance connections do. You can’t run a single field wire, pre-1970 alternator on a ’70 and up dual isolated field/electronic regulated wired car.

 

[Mark1972]

Ammeters don’t cause problems, lose or high resistance connections do. You can’t run a single field wire, pre-1970 alternator on a ’70 and up dual isolated field/electronic regulated wired car.

It is a dual field alternator. I checked up on this first thing when I got it. Apparently it is common for new replacement pre 1970 alternators to come with dual field attachments. According to the previously linked schematic, it was wired correctly. This is why I will start from scratch tomorrow.

 

[72RoadrunnerGTX]

No such thing as a pre-1970 dual Insulated field alternator. You indicated you bought an alternator for a '69, should have a single field terminal. What is common these days is to find a brush kit for a ’70 and up alt on a pre-1970 alternator, appearing to have two field terminals. Problem is one won't be insulated from the case. Pull the two field spades connections off the alt, check for continuity from the terminals to the alt chassis. Should NOT be ANY continuity to the case from either terminal.
You indicated the blue wire burned, that’s the ignition run side of the field circuit, that indicates a dead short at the alternator.

BTW, you can run a ’70 and up insulated dual field alt on a pre-’70 car, with mechanical regulator, but you have to ground one of the field terminals.

 

[bm02tj]

check with your Ohm meter to see if they grounded one brush as you did order for 69

 

[Mark1972]

I just did an ohms check on both poles. The lower one in the photo without the hole in it tested 0 ohms, the other pole tested 4 ohms. So knowing that, what change do I make to the wiring or should I go back and get a proper 1970 alternator?

 

[72RoadrunnerGTX]

That’s a later square back alternator, with insulated field terminals, should electrically work on any ’70 or later application. However, again there should be NO continuity from either terminal to the alt case. From the picture, it appears your fiber insulating washer that should be under the screw head is missing. Upper one appears to be present. The mounting screws should not be touching the terminals. If you just bought it, take it back and get one that is assembled correctly, take your multi-meter with you if you have to.

 

[texas69bee]

Voltage regulator for 69 and earlier

PowerMaster round back with a dual field. If used with a 69 voltage regulator then one field has to be grounded to the case.

70+ dual field squareback

70+ voltage regulator

 

[Mark1972]

Omg, I never even saw that washer missing. My neighbor had some insulated washers and gave me a couple. Now I'm getting no continuity on either pole. Can't believe I didn't see that. I'm going to replace the wire that burnt and try again. I'll give NAPA a call Monday morning. Thanks again for the help. Maybe sailing would have been a better hobby to take up in my late 40's, lol. Then again I probably would have sunk the boat.

 

[Nacho-RT74]

This alternator althought roundback, is setted up to 70/71 dual field and elect reg. Rear case accepts both setups. The hole on right side is to fit the grounded brush without prong to be installed earliers single field systems

To the OP... as mentioned, the alt was modified to be used with single field mech reg setups, removing the fiber washer and even installing a metallic washer in place. That's a valid procedure to retro fit squarebacks on earliers setups but I allways advice cut the prong of the grounded brush to save from the short you got, because earliers setups even using just one wire and is green, these green wires drives positive on earliers setup, while on lates drives negative. The green wire just indicates is the source provided by the regulator, which was changed from positive to negative when elect reg came out.

The bad luck made you plugged the blue wire ( ign system source from RUN circuit at key ) straight to the grounded brush. If you were installed wire backwards, you have got full fielded alt but no wires burnt

 

[Mark1972]

Well it's good to go now. Got a new wire in place, and the proper insulated washer on. No more short. This removes a heck of a lot of stress. Just thanks again to all who responded. Everytime I'm on this forum I learn something that I can then pass on to others who may have the same problem. Actually joining my local Mopar club this week. Long overdue.

 

[texas69bee]

This alternator althought roundback, is setted up to 70/71 dual field and elect reg. Rear case accepts both setups. The hole on right side is to fit the grounded brush without prong to be installed earliers single field systems

To the OP... as mentioned, the alt was modified to be used with single field mech reg setups, removing the fiber washer and even installing a metallic washer in place. That's a valid procedure to retro fit squarebacks on earliers setups but I allways advice cut the prong of the grounded brush to save from the short you got, because earliers setups even using just one wire and is green, these green wires drives positive on earliers setup, while on lates drives negative. The green wire just indicates is the source provided by the regulator, which was changed from positive to negative when elect reg came out.

The bad luck made you plugged the blue wire ( ign system source from RUN circuit at key ) straight to the grounded brush. If you were installed wire backwards, you have got full fielded alt but no wires burnt

Nacho-Rt74... As I stated under the pic, the brush would have to be grounded to the case. This is simililar to what the OP accidentally did. Is there something different about the hole to the right compared to where it is at with the fiber washer missing?

 

[Nacho-RT74]

well, the roundback with a grounded brush on the right hole for mech regs ( single field ) won't have the left side brush with a prong. The grounded brush won't have a prong so would be imposible to connect... these will be the correct alts up to 69. Neither have the plastic brush housing/isolator. Brush is inserted straight into the aluminium alt case

There are several other roundback alts to the 70/71 period without the grounded brush provision, and just with both isolated provisions

I'm just remarking these different options from how they look.

 

[Bogey]

Wow, thanks to all for the documentation and all the detailed description. I just went through this exact scenario and can't thank all of you enough.