99 Q45t brake and battery light on, WHY???

[Shonn]

Ok so I own a 99 Q45t with about 117k on it. Runs fine. Except for this intermittent brake and battery light thing. I searched and found what I suspected it to be, the alternator. BUT, when I had both the battery and alternator tested the tests came back good. They're both in working order. The alternator is charging like it should and the battery has good voltage. I've went to a couple places to check it out. One of which was an actual Infiniti dealership. But of course the lights weren't on when i got there. lol. So what are your thoughts on what it could be? I checked the brake fluid level and it's fine. But would that cause the battery light to come on as well? The only thing I could think of is that my passenger side foglights housing is broken. So maybe water got on the light or something and is shorting/grounding something out. The other thought would be a bad ground but it seems fine to me. Ugh, if someone could possibly shed some light on this it would be much appreciated. Thank you.

-Shonn

[BuckPennell]

I don't think I'm any help, but I have a 99 Q45t that does the exact same thing from time to time. It's been happening off and on for quite a while, never has actually caused a problem, so I don't worry much about it. I'll be keeping an eye on your question to see if someone has an answer.

[Shonn]

Someone suggested I change my brake fluid. Because it looks pretty old and gunky. So the float maybe getting stuck or something, ionno. But yea, definetly keep an eye out for a solution.

[maxnix]

Never let any fluid get "old and gunky" unless you want to replace the system it supports. ABS is very expensive, not to mention master cylinders and brake caliper piston seals.

The OP should check brake fluid first, but I am betting on battery/alternator.

[Shonn]

well like i stated. I ran a couple charging system tests and they all came back fine. Both alternator and battery are fine. Sooo, ionno.

[maxnix]

OK, please quantify "good voltage".

[Shonn]

Well I pulled the negative battery cable off when the car was running. Annnd it stayed on. SO, I now know it's not the alternator but something else. The car seems to run fine, but those lights are friggen annoying. Any other ideas?

[Q451990]

That is a very bad test for your alternator. The electronics are not designed to run on voltage that's not buffered through the battery!

The brake and battery lights double as low voltage indicators. Keep in mind that it's possible to have an intermittant issue with your alternator - so it's a good idea to keep a voltage meter in the car if you want to check it while the lights are on.

At the battery terminals you should see about 12.5VDC at rest, and about 14.4VDC at idle.

Heath

[Shonn]

Only thing is that i've tested the battery and alternator at a couple places already and both of there instruments said the exact same thing. Everything is fine. So there has to be some other underlying issue that someone is aware of. I hope.

[qship96]

Battery and alternator are 2 parts of the complete charging/storage SYSTEM- the third being the wiring/connections between the two......look for shorts,dirty or loose connections,animal chewed wires,etc

a multimeter with voltage/ohms function can tell you alot about the FLOW of electricity if used by a trained operator.

[BadQ45t]

Okay, so here is what you do. Replace all your fluids, do not dump them, flush them. Then buy a new alternator and a new battery, then report back. Your being really dumb with this, excuse my blunt take, but just get new everything and see where your at. A 13 old alternator is not running like new even if it is still working well (my 97's has 94' and mine is fine) but you should just replace the obvious and never let any fluid get gunky EVER if you want a future with this car.