Voltage Regulator?

[dakota farmer]

Hey Guys just had a question about voltage regulators. I have a 93, and every other month my lights go really bright then burn out........ So my question is where is the voltage regulator and is this my problem. On my 91 the voltage regulator is back above the motor on the firewall......but not on the 93..... Just curious on what i need to do. When my 90 voltage regulator went out it fried almost everything. JUst don't want that to happen again. Thanks

[PToombs]

The regulator is a function of the PCM. Strange problem, haven't heard of that one. Have you checked your grounds? They are a comon problem on these trucks.

[dakota farmer]

call me ignorant but what is the PCM......tonight on the way home from the farm the lights would flicker...... I just don't understand what is going on>>>> which grounds do I need to look into. Thanks for the help!

[Mark Nixon]

The "big" one to look for is the ground from the battery to the core support.
There is another ground right behind the head on the firewall.
I'd also look into the main charge wire connection from the alternator, which is the larger single-wire connector next to the battery.

When stuff starts blowing due to over-voltage, it's usually a bad connection somewhere in the charging circuit, usually at, or near, the battery end, or the alternator end.

Fortunately, we don't have to worry about ammeters on the Cummins trucks.
That would really bite.

Mark.

[dakota farmer]

Thanks alot for the help. I will look into that tonight. I know that their are some loose stuff on the battery. I am just worried that I am going to fry something if I don't take care of this now......because "knock on wood" everything works as of right now. Thanks Again.

[PToombs]

The PCM is the Powertrain Control Module. Fancy name for a computer. It's in the fender behind the battery.

[dpuckett]

DIg around here or on other CTD websites- there is a way to bypass the computer, and have a standard volt reg, but you have a constant check engine light.

[Billy Boy]

I ran into a problem tonight, and my guess is that it is related to the voltage regulator. I drove about three hours on the highway in the dark and in the rain tonight with no apparent problems. When I got off of the highway, I noticed a "sulfur" smell and assumed it was the local sewers overflowing from the downpour we were getting. When I pulled in the garage tonight, I popped the hood and the battery was smoking pretty good. I let the truck idle and checked the voltage across the battery - appeared to be about 14. I have pulled the ground off of the battery for now. I am planning to replace the voltage regulator this week, as well as check the charging circuit like Mark has suggested. Does anybody think this may not be the problem? Any other ideas?

Also, online NAPA lists two available regulators with two very different prices:
The Mileage Plus Electrical (MPE VR38SB) with a price of $14.99 and the Echlin Ignition (ECH VR38) at $41.99. Price-wise, the Mileage Plus is my first choice, but would anybody recommend the other one based on experience?

Thanks for the help.

[Richie O]

It is just 2 different lines of product. The echlin is the better quality. Still most likely made in china.

[Billy Boy]

It is just 2 different lines of product. The echlin is the better quality. Still most likely made in china.

I figured they were the same product but one might be better than the other...just wasn't sure if the echlin was worth the extra $25...especially considering they are both most likely Chinese quality!

[peobryant]

It is just 2 different lines of product. The echlin is the better quality. Still most likely made in china.

I figured they were the same product but one might be better than the other...just wasn't sure if the echlin was worth the extra $25...especially considering they are both most likely Chinese quality!

Our auto stores around here generally give the more expensive unit some sort of warranty. I'd see about a warranty, and if neither one of them have one, go for the cheaper regulator.

[Billy Boy]

Our auto stores around here generally give the more expensive unit some sort of warranty. I'd see about a warranty, and if neither one of them have one, go for the cheaper regulator.

Good advice, that's what I was thinking too. I think that is the route I will go.

[Mark Nixon]

I've found in the past that if you have a loose connection in the charge circuit, espcially on the trucks without an amp guage, the intermittant connection will fool the regulator into overcharging AND, on a stock voltmeter, it may not even move the needle.
An ammeter has a constant load state on it and shows every little connectivity issue in the charging state of the battery and electrical, but also is problematic in that it loads the hell out of wiring.

Your connectivity issue can be as simple as a bad ground, to as complex as a partially burned alternator winding, or diode.
I've even known a stripped nut on one of the alternator field wires to cause charging issues.

On dual battery applications, a calcated plate will cause an over charge state and you wouldn't know it until you got that rotten egg smell.
The truck will run, start and act fine, you just get "that smell" of a hot battery.
In short, the bad battery will take out the good one by means of overcharging it.
By the way, a calcated plate in a single-battery system can do the same thing.

The computer may very well be bad, but a fine tooth comb on the basic connections, plus a spin on a quality alternator machine won't hurt any.

Mark.

[cumminsfreak86]

I had a problem with the lights flickering so I replaced the voltage regulator. After that I discovered that my battery had been overcharging with that regulator and the battery was drained. Also my alternator was going out. So I charge the battery up and put a new alternator on tonight. I find out that I'm still undercharged with the new regulator. I then hook up the old regulator in combo with the new alternator and I'm overcharging again. I'm now thinking I just got a bad regulator. The lights have stopped flickering but, as I said before, I'm still undercharged. I only paid $15 for the new regulator so Im going to get a new one tommorow.

I don't know if this will help but it might give you an idea of how to narrow your problem down. I will let you know if the new regulator fixes my problem tommorow.

[Billy Boy]

Thanks guys. I replaced the voltage regulator with the less expensive one. I checked, sprayed down with cleaner and tightened the grounds off of the battery. I found what I hope was the source - a wire lead off of the positive terminal of the battery that had cracked under its coating and was down to just a strand or two of the wire holding it together.

I drove it around a few times for a half hour or less locally - long enough to get it good and warmed up - with no obvious problems. Yesterday I drove it home for three hours and everything seemed good (knock on wood!) Seems to have fixed it for now, hopefully there will not be any future problems.