Dim Idiot lights, new battery, tested alt.

[Waffles]

Hey, so I've got the dim battery, coolant, and brakelight problem, as well as dim headlights at idle.

I've already read a bunch of threads about this problem, but none of them helped, as they all said to replace the alternator, and I took it to the local parts store and it tested out fine.

The battery is under 3 months old and holding a good charge, and the alternator is also only less than a year old, i replaced it when my original one died while i was driving.

 

[stevo911]

Im guessing you got a sound system installed? Or a aftermarket starter etc...Something is draining your charge if you turn the idle up it will fix it for a bit but you need a stronger alternator. When the garage tests it they test it under minimal load you need a alternator that will give out a stronger charge so it can cope with accessories. If you got an amp or something unplug it ill bet your problems will stop.

 

[stevo911]

Coolant and breaklight turn on to indicate the alternator is charging and your battery is holding less then 14 volts. Hook a multimeter up to your batter when this is happening whatever number it reads is what your alternator is pushing if its less then 14.4 the garage is wrong and you need a new alternator.

 

[Mitsu RacerX]

I bet when u rev it up the meter drops. Mine did the same thing and come to find out the ALT. was going bad..When u stress the diodes out it drops and will not charge 14.4..

 

[luv2rallye]

You either have a very large draw that the alt can't handle at idle or the alt is bad. Auto store alt testing is near worthless. Only a shop that repairs alts tests them properly.

But do this:
Stop engine and with everything off measure battery voltage (should be 12V or higher). Start engine and measure battery voltage (should be around 14.4V within 0.5V or bad alternator). Now turn high beams on and again measure battery voltage with them on (should still be around 14.4V within 0.5V or bad alternator).

 

[Defiant]

Hey, so I've got the dim battery, coolant, and brakelight problem, as well as dim headlights at idle.

I've already read a bunch of threads about this problem, but none of them helped, as they all said to replace the alternator, and I took it to the local parts store and it tested out fine.

Their testing is inaccurate. Your alternator is not up to snuff. What is your voltage across the battery terminals at idle?

And don't dare hint that you don't have a digital multitester. They're five bucks at the grocery stores these days. And none of us miss the days of a $300 Simpson meter.

 

[Waffles]

No system, everything electrical is stock. 90 amp alt. with no draw other than headlights, and it's dim at idle. Damnit! I just bought this thing.
The store tested it and said it was good so i doubt they'll give me any kind of warranty.

And yeah, I do have a multitester, it was reading 14.2 at idle with no drain, then it dropped down to 13.3 when i turned the little old rear defrost on, which is why i pulled it and got it tested by the parts store as they would have anyways when i asked for warranty or anything...

 

[stevo911]

It definetly dead even 14.3 is a fail parts store shouldnt pass until it hits 14.4-14.5. You could always turn your idle up for a short fix but its a dead alternator.

 

[Waffles]

It definetly dead even 14.3 is a fail parts store shouldnt pass until it hits 14.4-14.5. You could always turn your idle up for a short fix but its a dead alternator.

Gah. Alright, time to go yell at some parts store retards.

 

[stevo911]

Ask them while they are benching it if they have a way to add a load to it. That way theyll see it drop like you did when adding the defroster.

 

[waterman412]

yea mine was very similar after like a week after havving the car. i got a new alternator and it was fine