I've got a nagging intermittent electrical problem with my 73 Valiant.

First, I should note that my battery is fine, alternator working great, regulator OK as well. The Valiant is my daily driver, but I'm only 3 miles from work, so it doesn't get much exercise except on weekends.

Last week in driving home from work, I noticed that the ammeter would occasionally dip well into the discharge (-) side of the scale, but would usually bounce right back after just a few seconds. I usually have the radio on during my commute, and I noticed that when I used the turn signals, the ammeter bounced into the discharge range AND THE RADIO CUT OUT COMPLETELY FOR ABOUT TWO SECONDS! ????

OK, so I played around with it over the weekend. Couldn't find anything wrong, and also could not get it to repeat the problem. Everything seemed back to normal.

That is until this morning. I park in an underground garage, so as I enter the garage I have to put my headlights on. And as I already mentioned, I have the radio on all the time. So radio is blaring away, and my nice, bright headlights are searching out a parking spot. I find one, and as I put it in reverse to back in, here's what happened: headlights got noticably dimmer; radio cut out for two seconds; and ammeter drops way down into the discharge (-) range.

As soon as I'm in the spot and shift into park, everything goes back to normal: the radio was actually already back on before I was fully in the space, but the headlights jumped up to normal brightness, and the ammeter goes back to normal, which is a whisker to the charge (+) side.
I let it idle in park for a minute or so, with no further problems.

Any ideas on what the heck is going on? I thought maybe there is a short somewhere in the upper steering column, and it sometimes shorts out, like when you put her in reverse. And since it doesn't happened consistently, that seems to make sense to me. But is there maybe some kind of electrical connection, wiring or switch on or near the transmission that could be shorting out from the reverse gear linkage? And whatever might be the cause, why on earth does the radio go out for two seconds and then come back on?

I'm open to any suggestions as to how to track this thing down.

John Gnorski
73 Valiant

Are you sure about the regulator???????

I had a flakey regulator and occasionally the amp meter would jump around. It would be discharging, then decide that it shouldn't be discharging and would really charge to make up for the discharging, then it would be fine for awhile.....

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I've seen regulators start to intermittantly go bad; suddenly stop for a short time, then start up again. It took about 6mo to stay bad long enough for me to identify it.

When alternator brushes get old, they can start making intermittant contact. I've also had alternators break and short out inside intermittantly.

A short could be large enough to pull the voltage below where the radio can operate, but be small enough to not burn out the fusible link. Just loosing the alternator output would cause the ammeter to drop to discharge, but not normally pull the voltage so low the radio quits.

An open in the wrong space can also make the alt quit charging, but again, the radio would seem to indicate the voltage is goes way low.

If the radio lost its ground, it would quit too, but that is very unlikely in your model, as it mounts to steel and can ground through the antenna too.

I would do the following in this order:

0) W/ the engine off, turn on the radio and the headlights for 10 min and measure the voltage.

If the radio keeps going, you know that you're not just loosing your alternator output momentarially; it must be worse. If the radio quits, you've got a (slightly) bad radio that is unusually voltage sensitive (and probably has an internal regulator going bad) and you might just be loosing your charging. In this latter case, your radio probably will quit entirely sooner or later.

1) Remove, inspect, & clean the ground connections on the regulator; they can make intermittant contact and often corrode a little.

2) Remove, inspect, & replace the alternator brushes - you can do this easily from the outside. Look for broken plastic insulators that hold the brushes. If the brushes have more than, say, 50K miles, or look worn, I'd replace them.

3) Unplug, inspect, & clean the bulkhead connector. That is the #1 place for mysterious electrical glitches to appear. Look for any sign of corrosion or overheating.

4) Unplug, inspect, & clean the ignition switch connector under the dash. Look for overheating and scorch marks.

5) While you're at it, pull & clean each and every fuse - even a tiny oxidation layer slowly building up over decades can make for big problems. Often, just unplugging and replugging in the same fuse makes odd problems disappear for another decade.

Intermittant problems are tough to track down; you just have to keep alert for clues.