All my idiot light come one as if the alternator was bad intermittently. The alternator is good. I have dataloged voltage on my haltech and it dosen't drop below 13.5. When I start the car they come on, and then go off as I begin to drive. Durring full throttle acceleration, they come on. I have an efan but there is no correlation between it being on and the lights being on.

I have relocated my batter, but I did it right.

3/0 ground wire battery to block 2 gauge ground near battery 2 gauge power wire to fuse, switch then to starter then to distro block feed efan main power and haltech.

4 gauge back to battery from alternator fused in both ends.

BTW I had it set up like this for a month before the lights started coming on.

Thanks...

 

This is a turbo??? S4 or S5???

I'd say you have a bad connection between the alt and the car, or the battery and the car, but without a voltmeter's reading it would be hard to say.

 

Thanks for the reply its a 90 base model with a 13b-re, haltech E8, etc.

I used the 13b-re alternator.

Voltage stays around 13.5 all the time. I check all the connections. everyhing seems good.

I think the circuit that senses voltage to light up the idiot light may be bad.

heard of this before?

 

Ok I need to retract some of my previous statments.

First the lights are comming on because the voltage is to high. 1round 14.5 volts as high as over 15.

Next what would cause this, a bad alternator is obviously a possibility, but could other wiring also cause it.

How would I test it?

Thanks

 

anything above 14.5 is bad.

Yes, you need to check the alt wiring.

 

Checked the alternator to battery wire, its good.

The second plug, is it the voltage refrence and ground refrence?

 

The small two wires, one is for voltage referance, the other is for reporting that the alt is on/running.

 

So if I check the refrence voltage being provided and find that its identicle to whats bieng put out then I know the alternator is bad right?

If the refrence voltage is lower for some reason then that would indicate a problem somehere else in the electrical system and explain why the alternator is putting out so much voltage. Why doesent the alternator get its refrence voltage internaly?

Is the second wire to the alternator "for reporting that the alt is on/running." used by the alternator to determine how much voltage to put out in any way?

Thanks

 

yes

How could it tell that the battery needs charging if it referanced itself.

NO, it is to report that the alternator is working. It is what triggers the alt failure relay on a S4 and the idiot/warning lights on a S5.

Ground if the alt is not working, 12+ volts if it is.

 

Could be a bad voltage regulator. It's probably internal... like inside the alternator itself. If that's the case, alternator needs to be replaced.

 

I thought that an alternator had a pre set voltage (14 or so) and it used the refrence voltage to detrmine if it was either under or over that voltage.

Unless there is some circuitry between the refrence wire and the battery, isn't it allready refrency itself, as the alternator is directly connected to the battery?

Thanks for all the input, I guess I will read up about this in the FSM and online.

 

Just wanted to give an update for this incase anyone finds this in a search. Problem turned out to be the refrence wire plug had a bad connection. Was causing 15+ volts. Replaced with spade terminals and back to normal.

 

My 90 FC vert started to light up all the warning light and the voltage shot up to 15+ last night . I stoped and it came back down , but the moment I tried to drive it would go back up and it looked like I had hit the high beams on the headlights without doing anything every time the voltage would go up . I first thought it was the alt. or the volt regulator but now I'm not so sure after reading that all that it could be is a bad connection on the refrence wire plug. I'm gonna get the alt. tested first and go from there.If anybody has some imput please let me know. Roloracer.

 

If you simply get the alternator tested the will likley tell you its good. First re seat the plug, try the car again and see what the voltage is. If it was really loose than you should be good if not, replace the plug.