PULSING EVERYTHING

[POWWAG]

What I’m suffering from is a pulsing electrical system. At lower RPM the amp gauge acts like a tach and everything brightens or dims with RPM. On the freeway at constant RPM the needle swings back and forth, the head lights act like cop pursuit lights.

These symptoms were the same before and after switching to the blue electronic voltage regulator. Wiring, connectors, and amp gauge appear to be in excellent shape. The alternator tested good at the parts store. Everything’s grounded to everything.

My 77 did the same thing years ago, cleaning connectors and a new amp gauge did nothing to fix it. After having the alternator tested (good) I put a new one on anyhow and presto bango all fixed. I don’t get how it can bench test good and still be the problem.

I’ve read all the MAD stuff about amp gauges and I don’t think any of that is the problem I’m having. I should be able to disconnect the 10ga. from the alt. and run a temporary 10ga. from the alt. to the starter relay as a test. The red 10ga. though the amp gauge should feed the system.

I’m going to go put the alternator off the parts truck on there to see what happens.

Don

[POWWAG]

Different alternator same symptoms!

Don

[wideblock]

bad dimmer switch, bad headlight switch??? mine did this with the fancy electronic regulator everyone recommends. after hours of hair pulling, cussing, and throwing things, i went and bought a good old trusty cheap @#% simple electronic replacemnet from napa for the mech regulator. problem solved. seems the new regs (fancy ones) are geared for more amps, the lower amp alternators dont supply the power needed to keep the fancy schamcny reg working smoothly. so i went back and put the fancy reg on and wired the truck for a dual field 80amp alternator, now i dont have any issues with wireing or chargeing

[POWWAG]

The whole electrical system is pulsing not just the lights. I'm waiting to here from Jeffc as he has guru status and has run one of these regulators for years. This is the Mopar performance electronic regulator P/N 3690732 for the old single field alternators.

I still think it’s an alternator issue. Same symptoms with the old breaker point regulator, I thought the new regulator would fix this.

My 77 acted the same (dual field alt. and reg.) and an alternator was the problem.

I’m stumped! Is it time to go to a new one wire alternator?

Don

[Jeffc]

Don,
I have a fealing that your on the right track,
but trey may have something, a weak alt can
check out but still be bad, bad shorted cell
in the battery could also be part of the problem.

Have you pulled your fuses one at a time and
seen if it make a differance?
A ground wire (or internal fault) that should not be can do this.
Since you have dealt with the most common cause,
poor grounds, that is the next step, checking
for grounded wires that should not be.
Have you checked for voltage drop from
alt to battery?
Even with EVR (one or 2 wire alt) you can get a little neddle swing, but should not be enough to notice much.

[66patrick]

I have a similar problem with my '66 Coronet. Once I start the car, the AMP gauge goes clear to "C". If I'm driving, the gauge goes way over to "C", unless I have the lights and fan on, then it stays more to the center. BUT, at an idle, I get the pulsing electrics, too. The alternator checks at 45 amps (stock), every ground is good, battery is good (13.6V), and I have the DC electronic ignition and blue regulator. My old '67 Polara wagon (383, bone-stock point ignition and old-style regulator) did exactly the same thing as the Coronet.

Obviously, something is going on somewhere.

[wideblock]

the big thing to take into consideration is most parts stores check the alt unregulated. they just spin it and see if it puts out, no load, no reg, and basically inaccurate. all it tells you is that the alt puts out. well, you already know that. weak diaodes, or a faulty contact in the alt will make it be very irratic under load. this will also confuse the regulator in its duties. you have already tryed 2 different alts, im assuming you know for sure the second one worked as it should befoire you put it on as a comparison. so i would say you have a wireing problem, or you still have a bad ground. id try the fuse box idea. pull one at a time and see if any of them make a difference. this may at least get you in the right circut. if it does no good, ohm out the wires from your alt to the rest of the truck, make sure they are all good, all the connections are clean and tight, and everything is grounded as it should be, if not better. id still be suspect of the regulator, it doesnt take much to fry them. im not saying the reg is the source of your problem, but may have been effected in a bad way by the problem. jeff is not the only guru here as many of us have faught electrical demons with the help of the site and without. hell, one of mine turned out to ultimatly be effected by bad trailer wireing way out at the back bumper. same exact symptoms you describe. you have got a wire somewhere telling the sytem you need the power, or you got a bad alt or reg that just isnt listening to thew system saying enough is enough. wish i was there to see it in person, but im not, so i say go over the truck, wire by wire if you have to. youll find the issue im sure. and when you do, youll probably dop like i did and go "why didnt i think of that before".

[POWWAG]

I was grabbing some lunch/ checking email before checking grounds and connectors again. I even sanded the paint off the new VR at install so the ground cable from the block made good contact.

Here's some good reading I found last night.
http://www.imperialclub.com/Repair/Elec ... oltage.htm

I'll find out what's causing this before it frys my electronic ign. and post the fix. Any further clues will be gladly excepted.

Don

[Jeffc]

Back when I frist installed the 2 wire system in 65 car
the new rebuilt alt I got darn near fryed my system, turned
the key on and it started smoking wires, took the alt
back to the store, they tested it and said it was OK
(I had already tested it and found one of the field posts was grounded to the case somewere inside, AH HA!!) and handed it
back to me, I told them I would not take it back and wanted anouther one, they said NO!! I said "BS" you got a voltage meter? I will show you what is wrong with this one!! and pull anouther one so I can show you the differance>> Kid dropped he's jaw when I showed him and I walked out with a new alt......... I should of just asked for the money back, hope that they didn't just stick it back on the shelf...

[POWWAG]

OK here’s the latest! Not running I’m getting 12.6v at the battery and 12.6v at the alternator. At an idle 13.6v at the battery and the alternator. Running it up to 1500+ it’s pulsing between 14.5v and 15.5v to 16v. This seems like normal voltages (except the pulses) from what I’ve read.

I did find an interesting thing when checking connectors, the nipple of the 10ga. from the alt. broke off flush. I drilled out the connector and ran the wire thru soldering it. This did not make any difference.

Pulling fuses made no difference which reinforces my thinking it’s all in the charging system.

I’m back to the alternator. Trey might have it with the thing not putting out enough juice to allow the VR to make up its mind.

Back to the books…..Don

[wideblock]

have you looked over your harness don?? on my 65 i went thru 3 alts, 2 regs, and a few tools in the next door field before i finally found the culprit. i had a brake light wire that had rubbed thru the insulation on the frame rail. this was telling my system it needed more juice whether it did or not. i placed a piece of card board between the bald spot and the frame and fired the truck up just to check, and my guage jumped up to the c side, then settled out in the middle nice and steady. i small piece of heat shrink, and i was back in bussiness. but this was after 3 days of checking everything i just knew was the problem. just a side thought, since your reg is new and the alt tests ok.

[POWWAG]

VICTORY!!!

Not running: 12.6v at the battery but only 11.6 at the feed to the VR. Started back from the VR, fuse panel OK, pulled the ign. switch and found resistance. Extra switch I had checked out OK, installed, started up, went to charge and settled down just like it should.

In conclusion skoady switch contacts was telling the VR more juice.

Thanks for the help guys…..Don

[Jeffc]

VERY COOL, HAD A FEELING THAT IT MIGHT BE SOMETHING LIKE THAT.

Just a matter of following the leads and crossing off
what checks ok.......