'72 Valiant has no power

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72valiant

72valiant

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Hello everyone, hopefully someone can help me get my trusty '72 Valiant running again.

I went to crank her up a couple nights ago and noticed the dash lights and outside lights seemed brighter than usual. When I put her in reverse the lights got noticeably dimmer. Right then the car just cut off on me. Now the lights won't even work. When I turn the ignition I get absolutely no response. I hadn't drove the car in about a week and it was dark, when I cranked it I thought I saw a spider web near my head but in hindsight I'm wondering if it was smoke I saw in the dark instead.

I cleaned the battery cables and the battery itself tests as good still. The car has the 318 small block if that helps.

I'm wondering if it's the fusable link and if so how do I find out for sure?

Thanks for any help.
 
sooo many ways to go here. could be voltage regulator, could be a bad ground. fusible link , you should find a wiring diagram for your car. usually it is coming off the wire from the battery. might need a VOM meter to trouble shoot.
 
Sounds like your regulator went bad because the lights got bright first.
 

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Still no luck so far. I replaced the voltage regulator and that didn't fix it. I had the battery checked out and it seems fine. I then used a test lamp on both sides of the fusible link and it seems good too.

I have a wiring diagram saved somewhere. I've never used a VOM meter before. Any idea if the cause would most likely be in the engine compartment or behind the dash?

I've had the Valiant since '97 but I'm a real amateur with fixing wiring issues. Any help walking me thru this is greatly appreciated!
 
Does anything "at all" work? "No headlights" or anything else would most likely be "in descending order"

Bad battery cable connection. See if you have power at the big starter relay stud

Bad fuse link. From the stud, follow it to the bulkhead connector and probe the terminal in the connector

Bad connection right in the bulkhead connector. Pull it apart and inspect

Bad connection(s) at the ammeter. Have to get up under the dash. Remove battery ground, reach up in there and "clip" an alligator clip onto the red ammeter terminal, hook the battery back up and see if you have power there. Wiggle the ammeter connections.

Last, most rare, but "can" happen is the factory welded splice in the black ammeter wire. This is a few inches from the ammeter in the black lead up behind the cluster

READ please, this Mad article which also has a simplified diagram of primary power

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

amp-ga18.jpg


I the image above, which is simplified, follow along. Follow the red cable from the battery to the starter relay stud. From there the fuse link goes into the bulkhead (RED)

The fuse link and bulkhead connector are your first two suspects

From there the red goes up to the ammeter, your next suspects

"Out" the ammeter on the black, one black goes back out the bulkhead and back to the alternator. "Before that" note the "WELDED SPLICE" This branches off and feeds the ignition switch, fuse panel, and headlight switch


Go to MyMopar, and download a free service manual for your car, or as close as you can get

http://www.mymopar.com/index.php?pid=31

Electrical is section 8

http://www.mymopar.com/index.php?pid=109

Also at MyMopar are third party wiring diagrams. These are sometimes simplified, and sometimes leave certain connectors and options out

http://www.mymopar.com/index.php?pid=24
 
Put a turbo on it. Gobs of power.

Ok, Ok, I'm sorry, I just couldn't resist.

Here's my take on it; Theres a short somewhere, or an open, possibly at the battery-clamp, that triggered the VR to send the alt into a frenzy. Meanwhile, the FL ruptured, and the ignition died from electron starvation. You cannot trust a voltmeter at the FL. If just a tiny remnant of copper completes the circuit, a voltmeter will read it. Give it a tug. Use two hands, one on either side of the flag.
If at any time you smelled burning plastic, look to the bulkhead connector, or the back of the ignition switch.
If I'm right go look for the short, before you hit the start button.Dell provided the magic which almost guarantees a solution.
If I'm wrong, try boostnit. NO, NO, kidding. If I'm wrong, the hunt is on........
Back to you, Dell
 
LOL AJ you been drinkin again?

I would absolutely suspect (bright lights) that something in the VR or alternator was the initial cause. You can leave the VR unconnected until you begin to get things "right" again
 
Oh boy, you just won't let it go with the worms, already.
You guys are the best.

Hey OP, bring it over to my house, I'll trade you for a good running 80 Volare. A slant 904.I'll throw in a couple of used VRs, and a known good alternator. The body is well used and probably could be brought back to life, by someone with a desire to do so. But she sure runs good!

OK, kidding again!
 
I'll look at it again and try the things suggested as soon as I'm able. The lights indeed do not turn on. When I turn the key there is no sound whatsoever - nothing seems to work. The light on my voltage tester lights up if it touches the battery, both sides of fusible link light up as well, but I can't get any reading from the fuses in the fuse box.
 
No horn, dome lights, brakes, anything? Anyway, listen to 67dart273. One of the better informed electrical guru's. I had a bad bulkhead connecter on my old 71 Swinger. Everything would go blank if that came loose, but you could see where the connector had overheated at one time. My best advice would be to eyeball wires, looking for anything melted or doesn't look right.
 
72valiant said:
I'll look at it again and try the things suggested as soon as I'm able. The lights indeed do not turn on. When I turn the key there is no sound whatsoever - nothing seems to work. The light on my voltage tester lights up if it touches the battery, both sides of fusible link light up as well, but I can't get any reading from the fuses in the fuse box.
Click to expand...

"Preliminary quick checks"

Turn on the light switch, and wiggle the engine bay side of the bulkhead connector. If that does not bring results, "reach up" under the dash and wiggle the wires on the ammeter
 
I reached up under the dash to wiggle the ammeter wires to find that they were both charred! I'm not sure if it's the positive or the negative but the inner wire has burned completely off the terminal.
 
There is no "positive or neg" they are both HOT. Red is battery "coming in" and the black feeds off to loads in the car, as well as "coming from" the alternator.

Read through that Mad article I posted, there's a lot of "good stuff" in there. The melted ammeter they pictured looks EXACTLY like some I used to see up here on pickups with snow plows.

"Stuff that can go wrong" with the ammeter and immediate area:

The molded wire ends themselves can fail down inside the insulation, get loose and "make heat"

The nuts can work loose or "been left loose" and make heat.

the ammeter itself. Construction varies over the years, but basically it's a pair of studs inserted through the brass shunt. This is not welded, and some years is not even exactly riveted. Rather, the whole thing depends on the compression of the nuts to "press" the whole thing together and make contact.

If something loosens..........well.........

Unless "you are married' to that ammeter this might be a great time to do the "Mad mod" and do away with it.

There is a thread on converting voltmeters to fit into the cluster in place of the ammeter:

http://www.forabodiesonly.com/mopar/showthread.php?t=119480

There's three pages, read through them, This covers several cluster styles
 
I've finally been able to find time to work on her. I took the dash partially out and here's a pic of what happened. That "Mad Mod" looks really interesting but I'm gonna have to find time to do that later down the road. I'm hoping to just clean this mess up and reconnect everything. Hopefully she starts after that.
 

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Reconnect? Not gonna happen. Your ammeter is fried. It may have failed / shorted right there in the cluster, or may have gotten loose and heated up the wire. There is VERY likely to be other damage. I urge you to inspect the harness carefully for damage

One serious consequence of overheated / melted wiring is that it OFTEN melts inside the taped harness "somewhere" and melts into other conductors. This can have "interesting" as well as "smoky" effects.

Depending on "what else" is or is not damaged, you might bet by specifically with those two wires of cutting them back to "good wire" and splicing them together.

PLEASE bear in mind that these old girls were UNDER protected, "fuse wise"
 
Ok, I'll attempt to splice the two wires together. I just hope I'm not getting in over my head. I'm not real experienced with wiring and electrical work. The terminal that the red wire was connected to is really loose. I'm guessing my problem started there.

I'm gonna go inspect the harness and look for signs of other damage.
 
Trace those ammeter wires through the whole harness along the cluster. I had a 69 Valiant that fried the wires and melted through many others in the bundle. I ended up rewiring most of the dash to clean it all up. :violent1:

But after that, everything worked fine and I stopped blowing alternators and regulators every 6 months.... :banghead: :D


PS: you can download a copy of the 72 Plymouth Service manual here:

http://www.mymopar.com/index.php?pid=109
 
I spliced the two wires together and put the dash back together. She cranked right up! I've driven her around the block and down the interstate a ways. Everything that was working before seems to still be working now (except for the ammeter of course). Thanks for all the advice. It's been very useful! I'm glad she's running again.
 
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