Voltage drop
- Thread starter O3 pharoh
- Start date
fastblackmerc
Everything Marauder, LEDs & HI
Do you have under drive pulleys? If so, you need to up the idle speed about 200 RPM.
Your alternator might be on the way out. Any FLAPS or Sears auto center can check your charging system for free.
Check all the connections from the battery and all the grounds on the engine and body.
Rockettman
New member
"Under drives"??
Does this mean you have them? Or you want them? If you want them with a voltage drop problem...you're going the wrong way. It'll get worse! This can be corrected with your tune (presuming you have a tune in the car).
If you've done the above mentioned already, and you're still having the issue; then you've got a problem that needs to be addressed.
Just upping the output of the alternator to compensate, is really not resolving the issue.
Does this mean you have them? Or you want them? If you want them with a voltage drop problem...you're going the wrong way. It'll get worse! This can be corrected with your tune (presuming you have a tune in the car).
If you've done the above mentioned already, and you're still having the issue; then you've got a problem that needs to be addressed.
Just upping the output of the alternator to compensate, is really not resolving the issue.
MyBlackBeasts
T242 - Ricer ricer
Under drives will ake the problem worse. Voltage drop is not normal. I recommend diagnosisng the problem and repairing it vs. trying to deal with the issue. If you deal with it, the actual problem will finally fail and you might get stranded... :shake:
No under drive pullies, I have a tune but still drops. Can the fake voltage Gage when stopped and AC, lights on I am down by 12 sometimes 10. Everything dims. I will try idle speed today. If alternator going is there a recommended replacement with clutch pulley? Thanks. Sorry for delay been wrapped up with work.
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RF Overlord
73 is the best number.
Only the oil pressure gauge is a fake...the voltmeter is real.
Paul T. Casey
Senior Member
If you notice this at low rpm's only, like at a stop at night say, it may be only a battery problem. If you notice it at all speeds, it's probably an alternator problem. I've had the u/d's forever without the bump in idle rpm, and have no major issues. I get the voltage drop, but that doesn't bother me. May slightly shorten battery life is all.
RF Overlord
73 is the best number.
Maybe not even that...Mary's had underdrive pulleys on Phoebe since 2009 and she still has the same battery we bought her with in 2007. I have no idea how old it is.
Battery tests fine, the AC draw is the worst, just noticing that it is dropping more than usual. That's why is was wondering if the under drives would free up any extra power to compensate a bit. Or maybe just a larger alternator pulley for more belt surface area? Not sure where to go with it.
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Spectragod
Willing to meet up half way
Under drives won't make it charge better, it will be worse, your alternator will be spinning slower.
What was the battery tested with?
Does the car put out 14+ volts @ idle, what is the voltage with a load on the system?
Is there a differential in voltage between the positive on the battery and the positive on the alternator?
If the unit is putting out volts, then it's time to make sure that it is producing amps as well, you need both to run the car and charge the battery.
That info is needed first before changing anything.
RF Overlord
73 is the best number.
^^^what Spectragod said^^^ All of it.
Underdrive pulleys free up extra power by slowing down the accessories, including the alternator. That's the opposite of what you want. If anything you would want a smaller pulley on the alternator to spin it faster, but I think you need to have the underlying problem fixed first.
Phoebe has underdrive pulleys and we had the idle in drive bumped 100 RPM to compensate and there's minimal voltage drop, even with the stock alternator, so you have some other issue going on.
Underdrive pulleys free up extra power by slowing down the accessories, including the alternator. That's the opposite of what you want. If anything you would want a smaller pulley on the alternator to spin it faster, but I think you need to have the underlying problem fixed first.
Phoebe has underdrive pulleys and we had the idle in drive bumped 100 RPM to compensate and there's minimal voltage drop, even with the stock alternator, so you have some other issue going on.
jus2rel
New member
Don't know if this helps?
But I probably spent over $2000 on batteries, alternators, and parts to try and fix my voltage drop. Same thing was happening to where it would drop to 10 sometimes and the lights would dim badly at night. It would also random spike to 16-17 sometimes and it really worried me. It was to the point where I would drive somewhere, get out, get back in and my car wouldn't start like a dead battery. Would jump it and it was fine for a month or so and happen again. It drove me crazy for 3 yrs but I was determined.
I finally took it to a shop that specialized in car and boat electronics. First they sold me an alternator like everyone else said, then as soon as I left the shop it did it again.
So I returned it and they saw it was still taking place. They spent the next 6 hrs going wire by wire to find the problem. After checking all the grounds for shorts and all the hot wires for draws, it boiled down to either the computer or a wire that ran directly from the alternator to the firewall. I forget what it was called but I can take a picture to show where it is. It runs directly from the alternator connection to inside the car. They ran a new wire and voila!!!
They changed that wire and I have never had a problem since.
But I probably spent over $2000 on batteries, alternators, and parts to try and fix my voltage drop. Same thing was happening to where it would drop to 10 sometimes and the lights would dim badly at night. It would also random spike to 16-17 sometimes and it really worried me. It was to the point where I would drive somewhere, get out, get back in and my car wouldn't start like a dead battery. Would jump it and it was fine for a month or so and happen again. It drove me crazy for 3 yrs but I was determined.
I finally took it to a shop that specialized in car and boat electronics. First they sold me an alternator like everyone else said, then as soon as I left the shop it did it again.
So I returned it and they saw it was still taking place. They spent the next 6 hrs going wire by wire to find the problem. After checking all the grounds for shorts and all the hot wires for draws, it boiled down to either the computer or a wire that ran directly from the alternator to the firewall. I forget what it was called but I can take a picture to show where it is. It runs directly from the alternator connection to inside the car. They ran a new wire and voila!!!
They changed that wire and I have never had a problem since.
Picture would be great! Would love to check it. At idle I sit well at 14 or so. But any accessories on and it dips. Dips bad in gear versus neutral, and worse with lights on. Add AC and wipers I'm down to ten and sometimes looks like it will die and end up in neutral bring Rpms back up. Never have trouble starting (hope I didn't just jinx that! ) thanks for all the input, would really like to put this problem behind me.
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Zim Hosein
Senior Member
+2 on wanting a PIC since the way you described the wire path, it "might" not be part of the "Big 3," which solved similar issues for other members in the past.
Thanks in advance! :beer:
Spectragod
Willing to meet up half way
Have you hooked up a DVOM and measured the actual voltage, or are you just going by the gauge in the car?
jus2rel
New member
Here is a picture of the wire that caused me electrical headaches for over 3 years. Its the green wire that was spliced in at the alternator and re-ran. Every time I told a shop the symptoms, they all said alternator or bad grounds. Yet, it was a break inside the insulation of the previous wire that was causing all the problems.
After replacement, no more issues and its been almost 3 years.
After replacement, no more issues and its been almost 3 years.
Attachments
Spectragod
Willing to meet up half way
Did a shop do that work? If so, while it may have fixed the initial problem at hand, butt connectors and wire begging to be chafed with no loom under the hood are problems that will cause other issues.
Otherwise, good find.
fastblackmerc
Everything Marauder, LEDs & HI
I was just going to say that.
jus2rel
New member
Again, it boiled down to that wire or the computer and I was prepared to spend the money to replace the computer if it would have solved the problem. He told me what that wire was for but I don't recall.
Thankfully they solved the problem. Replaced the wire, while although spliced, it works great and never had an issue. I have spliced may wires in my day and seldom had problems. If a problem does arise I know exactly where to look.
Thankfully they solved the problem. Replaced the wire, while although spliced, it works great and never had an issue. I have spliced may wires in my day and seldom had problems. If a problem does arise I know exactly where to look.
Spectragod
Willing to meet up half way
I have spliced many wires in my day as well, just not with butt connectors in an environment that is subject to moisture and grease (both of which conduct), soldering and heat shrink is recommended, worse case, use heat shrink butt connectors & loom over the new wire.
Still..... good find, I am sure it will help someone.