Getting cold out, voltage drop happening

[beaconhillkilla]

Hello everyone, It just started dropping below freezing here and I've noticed that at idle my battery, ABS and brake lights all light up. This happens both when I have driven the car for both short and long (1.5 hours on freeway) periods of time.

My initial thought is that my alternator is starting to give up the ghost. I believe the previous owner installed a new one sometime in 2012, but auto store rebuilds failing aren't unheard of. I'm running a yellowtop optima for a battery that was purchased new in 2011 so I highly doubt that's causing any sort of issue.

I'll have access to my tools Saturday so I can pop the alt. out and run it down to O'ReillyZone to have them bench test it. I'm just curious as to why all of my dash lights less the CEL come on, am I right in my assumptions?

[cj91legss]

I think it's just the weather. I have this pos 85 nissan pickup I use for work and it's battery light was flickering yesterday on my way to home depot. It too has a reman alternator only a year old.

[ACVWguy]

Sounds like an alternator failing to me. I bought an AutoZone alternator three years ago with the lifetime warranty and have had to replace it no less than 4 times. Everytime they start to fail the dash lights start to flicker. When they finally fail, the ABS, battery, and brake lights all stay lit solid. And if it helps, all of the alternators failed in cold or wet weather.

Parts store reman alternators are garbage.

[Legacy777]

Those dash lights come on because they are supposed to. There is a circuit with those lights and a circuit in the alaternator. If it fails to produce 12v or the voltage drops to ground, current will flow and those dash lights will light up. As I said, this is by design and to let you know if the alternator is having issues.

[91Beater]

I would check for corroded wiring and grounding. As things expand and contract with temperatures, corroded connections make intermittent problems. Check the voltage at B+ terminal at the alternator and make sure the voltage feedback sense is hooked up so that the alternator knows the voltage at the battery and regulate accordingly.

Check the voltage between B+ and positive post on battery.
Do the same between alternator frame and negative battery post.

You're gonna do it in 2v or 200mV range.
The readings for each should be as close to zero as possible.

Check the voltage between + post and sense terminal. This should always stay within a 10mV or so. The alternator attempts to regulate to a set point based on what it reads on the sense terminal, so a flickering expected if this one is jumping around.