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On my 65 W300

You guys were a great helping me fix my clutch problem, so here's an electrical question.

My voltmeter reads about 13v but pulses slightly.
When I turn on the lights it pulses a lot more and the dashlights pulse and the headlight brightness changes.

So where do I start looking to fix this?

I had the same issue with my 71. It turned out to be the "voltage regulator" Which is located on the firewall. I would start by replacing that.

If that doesn't work, you could have a ground issue. There should be a ground wire running from one of the bolts on the voltage regulator to the block, make sure it's still intact.

IF you have the time, run a new ground wire from the cab to the frame. Run a new ground wire from the block to the frame.

Try the voltage regulator first, I'll bet that's the issue. I do recommend grounding also.

Good luck and keep us posted!

Check your grounds. The engine block to firewall ground, ideally, should
not connect using one of the V/R bolts. Take your V/R off the firewall
and scrub up the back of it [and the firewall] to ensure good grounding.
The "pulsing" may indicate a shaky V/R. If it helps, you can also go to
http://www.marksmopars.net and ask Mark about a bypass check on the V/R
and, if the V/R is junk.... he knows the part number for a Filko V/R that
I can't seem to locate. I'm sure more will follow from other folks.
John

welcome to the dodge problem!! i have cleaned, replaced, and added grounds all over my truck. new VR, new alt., all new cables and even went as far as to crimp new ends on all the wires. what did this accomplish??? no more pulsing, but shes still going dim at idle. i just chalked it up to the nature of the beast and live with it.

Speaking of alternators.... if you're having troubles with yours and it
doesn't bench test adequately..... stick with the stock amperage or as
close to as possible or you'll run the risk of cooking wires.
John

sounds like you may have lost one of the diodes in your alternator

John, I pick up an electronic V/R from Jegs to replace the breaker point style V/R on my 67. It is a Mopar part and the price was good. I have not installed it yet as I had to go to Albuquerque on this job right after I got it. Jeffc turned me onto the part number.

Later.....Don

Hobcobble wrote:Speaking of alternators.... if you're having troubles with yours and it
doesn't bench test adequately..... stick with the stock amperage or as
close to as possible or you'll run the risk of cooking wires.
John

Tend to agree with John to a point on this, the 35 to 40 amp
alt's these trucks came with is under kill, the stock wiring
up to the 68 will handle a 65 to 70 amp alt just fine and not
cook wires, the later trucks are able to handle the 100 amp
jobs stock.

The elctronic voltage regualtor that Don brought up is
part #312-p4529794 for the 68 and earlier one wire
alts, needs no modifcations, plugs into the stock wire harness.$19.99
at Jeg's. I have been using one on my 66 for years.