1999 Ford Ranger XLT - Dashboard Battery Warning



Couple days ago while driving on the highway, my battery warning indicator turned on and noticed that the battery guage dropped towards the low side but not completely to the bottom. The dashboard lights dimmed also. I slowed down to pull over to the side of the road and the indicator went off and lights came back on to regular brightness.

Now over the past few days, the indicator light will come on typically when I go over 40MPH and the guage always drops. I had battery and alternator tested and both came back fine. I cleaned the posts and connectors on the battery for corrosion.

Last night as I was driving down the highway, battery indicator still on of course, the car lurched as if I hit the brakes, all my warning lights came on (ABS, Airbag, Battery etc.). Pulled over and it came back on. Had to pull off the highway and drive home on the side streets all the time keeping it under 40MPH.

I checked and put a little water into the battery as it was a little low but not bad. Text drove it and still the same problem. I am fresh out of ideas at this point. Any help would be appreciated.


It’s not a battery failure waring light, it is an alternator failure warning light. Your alternator is failing. Fix or replace it now. Soon you will be left stranded, and soon it will kill your battery and you’ll need to replace that too. (As the voltage drops due to the faulty alternator, it causes the various electronic systems [SRS, ABS, …] to start failing.)


Yes Agreed it could be the Alternator failing.

It also could be the belt tensioner has failed as well…& the belt could be bad, I’d replace it if has any kind of miles on it…Also the Idler bearing , couldn’t hurt to look at it as well.

Are you loosing coolant or oil?? might be loosing fluids on the belt making it not grip as it should.


Thank you. For future reference, why would the alternator test that it was ok if it is failing? Also, how come under 40MPH it rarely comes on if at all?


I will look into that. Fluid levels are all good and no leaks anywhere that I can see. I have had no squeaking of the belts or anything of that kind.


Your brushes are failing, and the springs don’t have enough force to keep them in good contact at high speeds anymore.


Thank you very much. I took it out and had it tested and it failed. I suppose it is an entirely different test than the first time since they took a tester out to my truck and hooked it up to the battery.

Thanks again for the help.