While driving my car has these lights turn on every once in a while then disappear, I know my cars battery and alternator are both good for sure as I had them both checked multiple times. What else could it be?

 

Did you check the voltage while the light was on? Is your brake fluid at the proper level?

This is where I'd start.

PS. Must you tease us with your outside temp!?@#

 

The light only comes on while driving so i havent had a chance to check to voltage, I will check the brake fluid level

 

Might need one of those cig ligher volt meter devices. Getting voltage at the cig lighter is not fully accurate. It will be slightly lower than at the battery but should be enough to give show if it's in the proper range or not (13.8 - 14.4 V or so).

 

When you have the battery light, as well as a brake light at the same time it usually means the alternator is failing. Just because it tested good when tested, doesn't necessarily mean there is not a random fault with the voltage regulator.

 

I figured I would ask in a old thread. My issue with my charging system is driving me nuts. I have the lights come on and go off at time. When the lights come on its when the alternator seems to stop charging at its around 11.8 volts. Then periodically it starts charging at 14.3 and rest around 13.6. It will flip and flop on and off charging. Had battery tested, alternator tested and passed of course. I took the alt off and took it to a alternator repair shop and they ran it for an hour and passed. I replaced the belt since it had some belt burn residue on it just in case. My terminal are clean and tight and I have upgraded wires for my audio system and I checked all connections. I also run 2 agm batteries and all seems to test out. One battery is a year old and the other is about 6 months.
So I'm guessing something isn't right in the regulator of the alt? Just bite the bullet and get a new one? I'm not missing anything to check am I?

 

I would take out the extra batteries and see if you still have the problems on just the oem batt setup.

 

Thanks I forgot to add that in my original post. I have disconnected it from the car

 

With your setup, do you have any grounding wires that are bypassing the battery current sensor?

 

What sensor would you be referring to?
Nothing is bypassed. The factory ground wires are still present. I just added additional 0 gauge along with the factory wires. It's like those grounding kits some use. Just bigger and to go along with the existing wires. All lugs are silver tinned and all connections are clean and tight. I took my volt meter and double checked all my grounds as well.

 

The negative battery cable connects the battery to the car frame. This cable passes through a current sensor which monitors the flow of current to/from the battery. The ECM uses this signal and, with the IPDM/er, controls the output of the alternator/voltage regulator.


Being that you added wiring (likely.bypassing the sensor) and batteries, it is possible the current sensor is not getting accurate readings which is throwing off the error. Some have had problems with grounding kits while others swear by them. YMMV.

I'm not saying this is your problem, I am just trying to brainstorm and throw some ideas out there. There are only 5 pieces to this puzzle (6 with battery) and wiring.

 

Thanks for the info I'll definitely check it out. It's just so wierd that's its been fine for a year then now I'm having issues. I'll definitely check the sensor and undo the stereo grounds and power upgrades just to rule them out. It's possible that sensor is faulty. If the system doesn't charge with the stock set up and the sensor is good I reckon something isn't right in the regulator that the alternator place missed.

Edit..
Thanks again. With further research about knowing about this sensor. It has been a problem adding upgraded wires. Some times it's not instant and some never notice it since the system still will charge. It doesn't charge at the full 14.x but at 13.x
I was thinking in my old school thinking of stereos and didn't even think of looking into the FSM about sensors with these cars

 

wow I replaced my ground cable and didn’t even think this lil sensor was important omg I replaced two alternators and been car less for like 2 weeks I’m ah go run my ground thru this sensor right now hopefully it maintains charge now I could not get my battery to hold charge let’s see if this works

 

Had tested my alternator myself and by my mechanic both passed I recently replaced a o2 sensor (bank 1 sensor 1) and this same issue started about a day after changing the sensor

 

I know this is an old thread but Im down the battery/brake light rabbit hole and have already replaced alternator and battery so in addition to verifying those are functioning properly I am looking into other electrical issues like bad grounds and voltage sensors/regulators. Did this end up working for anybody?

My car has tanked like 4 alternators and several batterys - trying to get to the source of the issue instead of repalcing alternators and batteries and hoping it will work for a period of time as clearly there is a severe underlying issue. Any input is greatly apppreciated!