4amp draw- high pitched whine from engine compartment- ignition off

[gluaisrothaii]

Hi Ken,

That is correct. I connected the brown wire to get rid of the flashing test sequence with the ignition on, but not started. There is more info here: http://dmctalk.org/showthread.php?12181-DMCH-alternator .

Thanks! Read through that....weirdly I do not have the flashing test sequence. I wonder if there's a new rev of the regulator.

Best,
Ken

[dmcnc]

Alternator would be annoying. It's brand new from DMCH. 300 miles. Whine was there with the engine off.

Just to clarify- alternator is topping battery off easily while driving, and running the lights etc, and the vehicle runs just fine. When turned off there's (sometimes) a real 4 amp electrical load that is depleting the battery. Something like a stuck relay. Whatever is consuming the power makes a high pitched whine in the engine compartment and doesn't show any signs of doing anything useful with the power.

I had the same issue with the DMCH alternator - it's more of a high frequency noise the engine was off. It killed a battery or two before I figured out it was the alternator. I would either get it replaced or go for another option.

[gluaisrothaii]

I had the same issue with the DMCH alternator - it's more of a high frequency noise the engine was off. It killed a battery or two before I figured out it was the alternator. I would either get it replaced or go for another option.

Wow! Thanks for that. I'll give them a call right now.

Ken

[gluaisrothaii]

Looks like the feed through the #191 bulb in the panel results in a 3 volt signal to the +L line on the alternator. Playing around with a potentiometer I was able to pull the alternator regulator online with a 0.4 volt signal- that's a low as I could go with the pot I had on hand (turned all the way down with a 1.5AA battery as the supply). It might come on with less that that. Seems like the alternator might be a little sensitive to something like a bad ground holding the voltage up on that feed line...

[Patrick C]

I had this EXACT problem with my DMCH alternator this fall! I went out to the garage and could hear a high pitched whining coming from the engine bay. I tried a lot of troubleshooting, but the whining noise seemed to go away on its own, but I’m not confident it’s gone for good.

[Michael]

For what it's worth when my DMCH alternator quit a few weeks ago it had a whine to it but it still charged at higher rpm. Low rpm was nothing. (I don't recall hearing any noise when the engine was off however).
I doubt I will never buy another alternator as long as these local guys rebuild it like they did this one. Almost 15v on the gauge at idle and in almost 11 years and 3 alternators I have never had the confidence to run the AC at night because with lights and ac fans, I would go into single digits.

My advice (which I followed from another member) is have yours rebuilt by a reputable place. Try to find a rebuilder that uses American components and has been in business for some time.

My rebuild cost $90.00 and it came back cleaned looking brand new and with a new pigtail.

[Bitsyncmaster]

Thanks! Read through that....weirdly I do not have the flashing test sequence. I wonder if there's a new rev of the regulator.

Best,
Ken

That is interesting that the DMCH unit now does not flash the error code (If sense is no hooked up). I wonder if DMCH is stocking a new alternator or if the manufacture changed the regulator.

[gluaisrothaii]

All,
Issued resolved- seems like a problem with the new alternator. DMCH replacement was sent and installed; all is good. Great service from DMCH! No more whining from the alternator with the ignition off.

Best,
Ken

[CFI]

All,
Issued resolved- seems like a problem with the new alternator. DMCH replacement was sent and installed; all is good. Great service from DMCH! No more whining from the alternator with the ignition off.

Best,
Ken

Lol, great service? Great service would have been sending a quality alternator the first time around

[Patrick C]

I wonder if this is a known flaw with the DMCH alternator. If mine is still doing this in the spring when I pull it out of storage, I’ll have to contact them for a replacement.