idle speed - Toyota Nation Forum : Toyota Car and Truck Forums

SuLLiVaN88 · 06-07-2010, 06:57 PM

so i have noticed that when my car is at the light idling i notice my volt meter drops. now it only happens when i have the ac on and is normal when its off i took some pics
here is idling at the light rpm

and my volt meter reads

then if i bring the idle up to

and my volt meter reads

and i notice my blower kicks down noticibly since there is an extra draw on the alternator
what do you guys think?

Rabbitbunny · 06-08-2010, 12:45 AM

I'd check the connections first. Use an ohm meter, you should be under 0.8 Ohm from the battery to where it connects on both.

90 GP · 06-08-2010, 05:14 AM

Autozone and Advance usually do charging system checks for free for piece of mind. From the guage indications even with the drop it still appears to be in the normal range. I assume you have headlights, a/c and blower running and all three create a load on alternator. I would say everything is operating as it should.

SuLLiVaN88 · 06-08-2010, 10:20 AM

Quote:

Originally Posted by 90 GP

Autozone and Advance usually do charging system checks for free for piece of mind. From the guage indications even with the drop it still appears to be in the normal range. I assume you have headlights, a/c and blower running and all three create a load on alternator. I would say everything is operating as it should.

ya ac and blower, no headlights tho. this morning i was driving it with the blower on 2 and it never did it. at the light my idle was like 700 then the radiator fan would kick on high speed and the idle would adjust up to like 950/1000 rpm. i know that my blower motor resistor is sort of bad since 3rd speed doesnt work. is it possible when its on the 4th speed it is pulling more power then it should?

90 GP · 06-08-2010, 12:01 PM

The 4th speed(high) on blower does draw the highest ammount of current. Add to that the blower resistor probably increases that load with the one speed out due to a bad connection/corrosion of one of the coil connections inside.

RED91SR5 · 06-08-2010, 12:11 PM

Quote:

Originally Posted by 90 GP

The 4th speed(high) on blower does draw the highest ammount of current. Add to that the blower resistor probably increases that load with the one speed out due to a bad connection/corrosion of one of the coil connections inside.

From what I recall, 4th (high), bypasses the resistor altogether and draws current directly from the fuse panel (battery/alternator). This is why the fan will work only on high when the blower resister goes bad.

You might have some corroded wiring in the car causing a drop in voltage, it is 20+ years old now. The drops you indicate do seem normal for a car of this age but you might want to take it in a have a diagnostic of the charging system done. Perhaps it's time for a new alternator.

SuLLiVaN88 · 06-08-2010, 01:14 PM

ya im not too terribly concerned with it but i will go have it checked out since it is free

SuLLiVaN88 · 06-11-2010, 10:46 AM

alright i took it to checkers yesterday and did a charging system test. it was 13.95 w/ no load and 12.93 w/ loads

RED91SR5 · 06-11-2010, 11:50 AM

Quote:

Originally Posted by SuLLiVaN88

alright i took it to checkers yesterday and did a charging system test. it was 13.95 w/ no load and 12.93 w/ loads

12.93v sounds a bit low under load. It might drop to there for a moment when everything is turned on but should go back up to 13.5~14.7 ish under load.

Before you go replacing an alternator or battery check that your grounds are all good and not corroded. You can also go to any parts store and buy extra ground straps and add them from the block to the chassis and battery negative. This might help. Other than that I'd say your alternator is on the way out.

SuLLiVaN88 · 06-11-2010, 05:22 PM

Quote:

Originally Posted by RED91SR5

12.93v sounds a bit low under load. It might drop to there for a moment when everything is turned on but should go back up to 13.5~14.7 ish under load.

Before you go replacing an alternator or battery check that your grounds are all good and not corroded. You can also go to any parts store and buy extra ground straps and add them from the block to the chassis and battery negative. This might help. Other than that I'd say your alternator is on the way out.

it only drops that low when idling and everything on but when driving it charges correctly according to the gauge. but when i have everything on and i only have the blower on 2 it never goes low on the volt meter which is why i wonder if the blower motor resistor is a suspect.
someone above had said they think the high speed by passes the resistor but i have heard from other people that it does not..

is 14 volts a normal charge amount with no load on the alternator?

RED91SR5 · 06-11-2010, 07:41 PM

Quote:

Originally Posted by SuLLiVaN88

it only drops that low when idling and everything on but when driving it charges correctly according to the gauge. but when i have everything on and i only have the blower on 2 it never goes low on the volt meter which is why i wonder if the blower motor resistor is a suspect.
someone above had said they think the high speed by passes the resistor but i have heard from other people that it does not..

is 14 volts a normal charge amount with no load on the alternator?

It "should" be just over 14volts even under load and at idle. I say should cause with a 20+ year old car the old wiring can cause a bit of a drop but in your case it sounds to low.

The blower fan on high DOES bypass the blower resistor but only on high. I have the wiring schematics if you like. Don't mistake the blower fan relay in any wiring diagrams for the blower resistor.