GMS626

Voltage Low When Headlights And/or Heater/ac Turned On With New Batter

22 posts in this topic

I just replaced the alternator and battery. When the engine is running the volts are at 13.80V - 14.05V. When I turn on the headlights the volts drop below 12.50V. When I turn on the heater the volts drop below 12.50V When I turn them both on the volts go down below 11V. With either on seperately or togather when the RPM's are raised the voltage drops even lower. When Everything is turned off again the voltage slowly climbs back to 13.80V - 14.05V. The voltage will not go back up unless i turn everything off, it just keeps dropping. When the RPM's are raised with everything off the voltage stays at 13.80V - 14.05V. I replaced the battery negetive cable and grounded it exactly where the original ground was on the transaxle. That had no effect. I started looking for other grounds. I found one ground by the engine coolant resevoir that is a junction with 4 wires connected into a plastic retainer grounded to the fender, I cleaned and refastened it. Under the plastic battery mount I found another ground that the bolt would not move from being so rusted so it popped off the car and brought a fist size chuck of rotted fender with it, it is now clean and regrounded somewhere else. I am still have the low voltage issue. I cannot find anything in the wiring schematics to begin a thesis on for a probable cause. I have followed the harnesses and still cannot come up with a positive i.d. on a cause. Whether it be in the engine compartment or inside the vehicle. Does anyone out there have any idea where or what is the cause? Thanks!

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New alternator and battery? It's possible you got a bad alternator, you'll have to test that separately.

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New alternator and battery? It's possible you got a bad alternator, you'll have to test that separately.

I will but I hope not, it is an AC Delco. Thanks!

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on my old 2.0 probe which is the same drivetrain, it did the same thing when i had multiple draws on the system. it never had the juice to run alot when just idling. i always just assumed they used too small of an alt stock. you could always upgrade to the 140amp alt maniac motors sells for our car. its less then 200 bux, and like 50 amps more then stock. it shouldnt have any issues at all powering everything, plus even more.

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on my old 2.0 probe which is the same drivetrain, it did the same thing when i had multiple draws on the system. it never had the juice to run alot when just idling. i always just assumed they used too small of an alt stock. you could always upgrade to the 140amp alt maniac motors sells for our car. its less then 200 bux, and like 50 amps more then stock. it shouldnt have any issues at all powering everything, plus even more.

Thanks, that sounds interesting! I am hoping that for now it is just a short somewhere. I had to do the waterpump too and of course the timimg so I am lowish on funds.

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Heres another question. Does the voltage regulator in the alternator control itself or is it controlled by the PCM/CPU? Could either of those two be faulty? I see in the wiring schematics just about everything including the heater and headlights is connected to the PCM. If not I guess I am going to assume that the electrical harnesses on the engine are bad because after a week now I have covered just about everything. Today I double checked the harness that goes from the alternator to the battery/main fuse box, everything there is ok. Tomorrow I wll try to remove the enitre harness for the headlights, I see that there is other wires along that harness connecting other various thingies. A defective new alternator would charge the battery after a drain or not at all? Slowly or fast? Thanks!

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It's the VR in your alternator, and it's probably failed.

It's not controlled by the ECU, it's built-in to the alt.

The alternator is new (remanufactured). But that is making alot of sense after going over just about everything else. Today before doing anything else I will take the car up to Auto Zone where I baught the alternator and have the battery load tested along with the alternator I baught from them. Thanks!

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I had a similar problem. Anytime i'd roll down the windows, push the brake pedal, turn on the ac, whatever... anything electrical, it would seem as if there was too much load on the electrical system.

I replaced the IAC, added two additional ground wires and upgraded the battery to 750 CCA.

There are other posts in here referring to the same issue, but this is the info I got from them and it worked for me.

Fixed. No problems since.

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I had a similar problem. Anytime i'd roll down the windows, push the brake pedal, turn on the ac, whatever... anything electrical, it would seem as if there was too much load on the electrical system.

I replaced the IAC, added two additional ground wires and upgraded the battery to 750 CCA.

There are other posts in here referring to the same issue, but this is the info I got from them and it worked for me.

Fixed. No problems since.

"IAC", Idle Air control Valve or something else? With the grounds you made, they came from the battery negetive? I am having a hard time finding solid grounding locations, so where to ground to is going to be important because right now I am stil using the one on the battery negetive to transaxle. So what I am understanding is to add two more grounds to the negetive battery terminal and ground them in seperate locations equaling three total seperate solid grounds with six or eight gauge wire? Thanks!

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Yea. First... It's my understanding that the Idle Air Control adjusts your idle when a load is put on the egine ie... turning the ac on, lights, power windows, etc...

It automatically increase the rpms just a bit so that you don't feel a loss in your idle. Typically there is a spring inside of the IAC that either get's stuck or breaks. Some of the members here have taken theirs apart and cleaned them and they worked fine. I had an extra $60 so I just bought a new one.

Second: Correct, two separate ground wires coming off your negative post on your battery. I actually went with 6 gauge as that is whats already on from the mfr. Home depot sells it for $1.10 a foot. I got 4 feet of wire and 4 (qty.) - 6 gauge circle ends (6.99). I took the 3 foot section and ran it to the pre-existing ground connection on the trans. underneath the air filter box.

I took the 1 foot section and ran it to the chassis right next to the battery. Drilled a pilot hole and put it in with a S/S screw and washer. There is one guy here who has pictures of how he did it. Here's the link to his post and pics.

http://www.mazda626....__hl__mazredman

Hope that helps, it worked for me. Here is the original post:

http://www.mazda626....ctrical-system/

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Gilly,

I am going to use your suggestions tomorrow. Today I was able to drive the car to Autozone since it was daylight but I drove without the heater (Booooo!). They thankfully exchanged the alternator with another one just to be safe and of course it had no effect except that when everything is off it now sits at 14.50V up from 14.05V. I can buy more parts when I get paid but tomorrow I will be able to clean the IAC, and make the two new grounds. I am not opposed to another new battery that is larger if it will fully correct the issue but that will have to wait until next week. So I am hoping that cleaning the IAC and making the two new grounds will produce results enough to get closer to resolving the issue. I appreciate everyones responses. Thanks a bunch!

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Well to be honest with you, if you have a 650 CCA battery it should be fine.

But, yea. Clean out your IAC, add those ground wires (cost you about $10 bucks). That should do it. Be sure to check those other posts (links) I gave you, for cleaning the IAC. As I said, I just replaced mine outright. The cleaning of it is more involved and a couple of guys on here have some good information as to how to clean it properly.

Good Luck with it. Let us know how it turns out.

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Yesterday I removed and cleaned the IAC valve. Doing so removed the Voltage drain issue. I have yet to make the two new grounds but I am still going to even though everything looks good because I cannot run the blower on level four. For some reason turning the fan to four causes a severe drain still. Other than that, with the lights on and heater and radio I am running at 14.50V. Thanks Gilly for the help. I really appreciate the advice. Same for everyone else. Without the help I would have been still staring at my motor in the freezing cold garage wondering what to remove and reconnect next.

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I honestly think the problem was with the original alternator.....14.05 V was too low and Autozone wouldn't have replaced it unless they thought so too! Now that you're at 14.5 (which is about where it should be) everything is better. As far as the heater drain I'm sure I have a TSB on that somewhere and will see if I can find it.

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I honestly think the problem was with the original alternator.....14.05 V was too low and Autozone wouldn't have replaced it unless they thought so too! Now that you're at 14.5 (which is about where it should be) everything is better. As far as the heater drain I'm sure I have a TSB on that somewhere and will see if I can find it.

I did have some question why the first new one ran at 14.05V and the second new one ran at 14.50V But the serious drops and continuing depletion of charge did not go away until I cleaned the IAC.. The car acted the same with the second new one on every test until I cleaned the IAC. But thanks for the advice. Now I just have a problem with an over load because when you put alot of load on the charging system the belt starts squealing real loud. I turn off the heater and it goes away. Thanks!

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Tighten the alternator belt maybe? Mine had the same issue but I found out from a local Mazda mechanic if you don't use OEM Mazda belts they come loose easily.Two bolts to tighten it,very very easy job.

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I took it for a test drive the other day and the water pump alternator belt broke, and it was squealing again. I had the heat and the low beams on. I baught a new one and did the tension according to the specs from the "Haynes" manual. Everything works good now, except that when alot of load is put on the alternator the belt starts squealing but the Volts stay up in the mid 14V. So I have decided that for now I can just drive the vehicle while keeping the load on the alternator down a bit. At least its major suffering is over because before I cleaned the IAC like Gilly said to do and make the new grounds I couldn't even drive the car. So thanks again guys for the help. Much appreciated! When I have more money I should be able to solve the remaining issues.

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belts dont squeal because of a load being placed on them. belts squeal because there old and degraded, or there too loose, too tight, or one of the bearings in one of the pulleys being bad.

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belts dont squeal because of a load being placed on them. belts squeal because there old and degraded, or there too loose, too tight, or one of the bearings in one of the pulleys being bad.

A bad bearing induces an unusually high load [beyond the design value] on the belt, so it slips, producing the squealing sound. Friction is indeed a load.

Mono brings up a good point, though. Have you considered that perhaps it's not the alternator that's the problem? What if some other accessory on the same belt is causing the belt to slip, so the alternator stops spinning [or slows down]?

For example, on the V6 models [would have to check my 4 banger to be sure, as I rarely have needed to touch that car], the A/C compressor is on the same belt...if you turn defrost on, the A/C compressor runs [to dehumidify]...and if the a/c clutch is sucking down too much power, you will strain the alternator....or if the compressor bearings are bad, or the compressor vanes are jammed, and it will put a large load on the same belt as the alternator, and possibly slip around the crank pulley....

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belts dont squeal because of a load being placed on them. belts squeal because there old and degraded, or there too loose, too tight, or one of the bearings in one of the pulleys being bad.

A bad bearing induces an unusually high load [beyond the design value] on the belt, so it slips, producing the squealing sound. Friction is indeed a load.

Mono brings up a good point, though. Have you considered that perhaps it's not the alternator that's the problem? What if some other accessory on the same belt is causing the belt to slip, so the alternator stops spinning [or slows down]?

For example, on the V6 models [would have to check my 4 banger to be sure, as I rarely have needed to touch that car], the A/C compressor is on the same belt...if you turn defrost on, the A/C compressor runs [to dehumidify]...and if the a/c clutch is sucking down too much power, you will strain the alternator....or if the compressor bearings are bad, or the compressor vanes are jammed, and it will put a large load on the same belt as the alternator, and possibly slip around the crank pulley....

Good points! The only two items on the smaller belt are the water pump and alternator. Alternator is brand new and the water pump was removed and inspected and was found to have zero faults. I had baught a new water pump when I went to do the alternator but when I removed the old one I physically inspected it and compared its movements to the new one out of the box and there was absolutley no reason to replace it. The shafts spins freely and without restrictions. There also was no play or any hint of any malfunction in the shaft. I could not bring myself to replace a perfectly good part.. That water pump probably has alot more miles on it. It pretty much seems new all around.The other larger belt has the Power Steering Pump and A/C compressor. I baught the belt to bypass the A/C crompressor since it is broken anywho. So that one is just the Power Steering Pump. My origianl thought was it was the A/C compressor but the bypass belt had no fix for the squeal. So that is why I am leaning towards the overload on the Alternator because everything is 100%. And if the Power Steering Pump is slowing down why is it doing it when the car is in Park? So however I did start the motor with the Power Steering belt off and just the Alternator and Water Pump and that is how I came to that theory because it was squeaking. The same squeak. Unless there are two identical ones. Thanks again for the replys. I got to drive the car today to and from college. With the lights on and the heater on "1". But it was nice to drive it again. And it was on the freeway! Thanks!

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