DEAD 1972 plymouth valiant

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thomas cox

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Driving back home last week and as soon as I put my lights on the car bucked and misfired. The voltmeter went all the way to the right and everything shut off. The next day looked and found the blue fuseable link was burned. replace link and when I turn the key nothing . not even a click. Going to replace the voltage regulator and the ballast resistor. Can anyone help. Battery is fully charged.
 
Please do not replace anything until you do some troubleshooting. Likely the LAST things you need is either a VR or ballast

You need to do some "stuff"

1...Wander over to MyMopar and download the 72 Plymouth service manual, which is FREE Also download from the wiring section, the 2 page aftermarket wiring diagram. These are not always as detailed or as accurate, but can be easier to follow

2...If you do not have, get yourself a basic multimeter and a 12V test lamp, and either some alligator clip jumper wires or at least alligator clips to make a couple.

Next, read this article. You do NOT need to do this "mod" necessarily, but read the article so you are aware of the why how and what. And there is a nice diagram there of the main power distribution in these girls

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

amp-ga18.jpg
 
Now you say, you "have nothing." What exactly does that mean? Do you have interior lights? Do the headlights/ tail lights work? Does ANYTHING work?

If the answer is no, refer to the diagram above. The main power distro comes power from the battery, to the starter relay 'big stud' which is a junction point. From there the fuse link feeds into the bulkhead connector (the big RED ammeter wire) to the ammeter and through it, out on the ammeter BLACK, and to the under-dash WELDED SPLICE. This splice branches off and feeds the HEADLIGHT SWITCH, the IGNITION SWITCH, the fuse panel HOT BUSS, and back out through the bulkhead connector (large BLACK) to the alternator.

Your troubles are likely........the fuse link you replaced is not making contact.........the bulkhead connector terminal(s) are bad, the ammeter terminals/ the ammeter is bad, the welded splice is AFU.

It also could be that "something failed" and is the reason the fuse link blew open. It might be that something in the alternator / field wiring/ ignition system/ other has caused that problem. IT MAY HAPPEN AGAIN

One thing you can do to prevent a short from causing further damage is to insert a large wattage bulb in series with the battery round. Use such as a stoplamp, or old hadlamp. The car will not crank, start, or run, but this will limit current flow and prevent "smoke"

Since you say the failure occurred when you turned on the lights, the FIRST thing I would check is the dimmer switch area. Since it is mounted to the floor, look for something broken/ bare wires/ a possible short in that area The headlights are NOT fused. They only have a breaker in the headlight switch, and it certainly is possible the main link would blow before the headlight switch breaker
 
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67Dart273 said:
Please do not replace anything until you do some troubleshooting. Likely the LAST things you need is either a VR or ballast

You need to do some "stuff"

1...Wander over to MyMopar and download the 72 Plymouth service manual, which is FREE Also download from the wiring section, the 2 page aftermarket wiring diagram. These are not always as detailed or as accurate, but can be easier to follow

2...If you do not have, get yourself a basic multimeter and a 12V test lamp, and either some alligator clip jumper wires or at least alligator clips to make a couple.

Next, read this article. You do NOT need to do this "mod" necessarily, but read the article so you are aware of the why how and what. And there is a nice diagram there of the main power distribution in these girls

Catalog

View attachment 1715638988
Click to expand...
Thanks for the info.
 
thomas cox said:
I already had a voltmeter guage on the dash replaping the old guages. its an ammeter. Could that guage be burned up?
Click to expand...

That's why you need to make some checks and yes

Also we need to clear up here. Do you still have the original ammeter or was it replaced by an aftermarket ammeter or did you remove it and replace it with a voltmeter?

Also, BE CAREFUL. Disconnect the battery ground. If you still have an ammeter, those are high current connections and you can burn stuff down. If you replaced the ammeter, the original big red and big black must be bolted together (and taped) which had originally connected to the ammeter
 
I would start at the bulkhead that goes through the firewall. Look for burned connections there. The hot wire to the ammeter goes through there and if there is a short will melt that connection immediately, seen it dozens of times...
 
disconnect battery positive, run a 10 foot wire back from postive lead to a DMM - in (audible) continuity mode and start probing the path with the positive red probe, start at the fusible link and then to the bulkhead connector, etc. No chance of sparking anything like this but there are many ways to trace a circuit.
 
67Dart273 said:
That's why you need to make some checks and yes

Also we need to clear up here. Do you still have the original ammeter or was it replaced by an aftermarket ammeter or did you remove it and replace it with a voltmeter?

Also, BE CAREFUL. Disconnect the battery ground. If you still have an ammeter, those are high current connections and you can burn stuff down. If you replaced the ammeter, the original big red and big black must be bolted together (and taped) which had originally connected to the ammeter
Click to expand...
 
Run a high gage cable from the alternator output stud directly to the battery through a fusible link and bypass all the b.s. Everything else is asking for trouble.
 
jos51700 said:
Run a high gage cable from the alternator output stud directly to the battery through a fusible link and bypass all the b.s. Everything else is asking for trouble.
Click to expand...

Well at least FIX THE PROBLEM before you do so
 
67Dart273 said:
Well at least FIX THE PROBLEM before you do so
Click to expand...

Shoot. My mistake. I forgot to preface my reply with, "don't FIX THE PROBLEM. JUST run a wire blah blah blah."

I'll try to be more concise next time.
 
LOLOL. Well I've run into this. The thing won't work so let's rebuild it and introduce 16 additional problems, while not fixing the other one. Used to be an amateur radio operator, we called him the "golden screwdriver" and that was NO compliment. He would scan the Portland papers for estate sales, then go talk the widow out of a Great Big Bunch of ham gear, then part it all out and sell it. And when something did not seem to work as he expected, he would immediately "golden screwdriver" it. Of course he never told this to prospective buyers.

I damn near hit him once at the Tacoma "hamfest." Came up to me wanted to "bury the hatchet." Yeh, I'll 'bury the hatchet', all right.
 
I'd like to cut all those wires out from the bulk head and splice them together. then no bulkhead to deal with. has anyone ever done this..
 
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You could. It is simple, if you are careful, to make a plate the same pattern as the connector. This will allow you to snap the plate in place using the factory gasket and clips. Punch a hole, find a big grommet. You might be able to buy them from the aftermarket wiring joints like Painless, etc

Be sure to use a big enough grommet with enough stretch that you can add wiring later, like a tach wire, etc, whatever.
 
67Dart273 said:
You could. It is simple, if you are careful, to make a plate the same pattern as the connector. This will allow you to snap the plate in place using the factory gasket and clips. Punch a hole, find a big grommet. You might be able to buy them from the aftermarket wiring joints like Painless, etc

Be sure to use a big enough grommet with enough stretch that you can add wiring later, like a tach wire, etc, whatever.
Click to expand...
 
thomas cox said:
I'd like to cut all those wires out from the bulk head and splice them together. then no bulkhead to deal with. has anyone ever done this..
Click to expand...
i have. mine had a few melted cavities.
tips,
A: have a factory manual
B: double check someone hasn't re-routed something and that all the wires are in the right place
C: learn to read the manual before you start cutting
D: pull the front seat and put some packing blankets on the floor

i unplugged everything on the engine side and popped out the cavity fitting from the firewall. that way i had working room. i did one at a time. i used THESE style butt connectors with a double layer of shrink sleeve over each splice. use GOOD crimpers. i use sta-kon pliers for this style connector but there's others out there. i also removed wires i no longer needed and added a few new ones. everything worked first time. you need to workout how you want to seal the hole too. at the moment i just have a block off plate i fabbed since i moved where the harness goes into the engine side.
i am going to redo mine. i want to re-route the main harness under the fender and get a cleaner look, but just removing the plug is not that big of a deal.
of course if you ever have a problem you might be cutting instead of unplugging something to fix it...

good luck
 
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