battery light comming on/off - vehicle voltage seems fine - Ford Ranger Forum

granger · 08-24-2009, 09:50 AM

Hi Everyone, thanks in advance for any help..

i have 2008 Ford Ranger 4.0 4x4 72000km, bought new last year..

the other day driving on the highway random dash lights started coming on and off, the abs, e-brake, airbag, and battery light would alternately flicker on and off... eventualy that stoped happening and now all that happends is the battery light comes on for a bit then goes off.. usualy when it comes on, all the gauges completely stop working... it has never lasted for more then 1 minute. i havn't had the chance to test the voltage WHILE the propblem is occuring.. but when the vehicle is idling i get steady 14.2V at the battery and at the cig lighter outlet, even after i turn on headlights on, interior lights and everything i can think of it goes down to about 14.1V. when the engine is off i get 12.9V.. i checked the alt belt to make sure it wasn't slipping and it seems fine... sounds like a bad ground to somewhere to me... not sure how to check that

something interesting is i changed the oil 2 days ago and droped a bti of oil in the alternator by accident.. i also cleaned the inside of the engine bay with spray cleaner and paper towels.. but i have checked everywhere i cleaned and nothign seems wet or loose... coincidently the issue started right after this.. Any thoughts????

Thanks.

Bill · 08-27-2009, 04:06 PM

Would think something is going goofy in the alternator. The alt light circuit puts power to the bulb and grounds in the alternator to complete circuit and hence light is on. As alternator charges, the former ground circuit becomes powered up and hence the bulb having power on both side of it, cannot light, (no current flowing). It might clear itself but if under warranty let them handle it.

granger · 08-28-2009, 09:58 AM

Bill, you are absolutely correct, the problem has been resolved now. i rigged up my voltage meter to a cigarette lighter plug so i could monitor the voltage as i was driving.. as i would accelerate and get into the high RPMs the voltage would spike up to 16-18V and the dash would turn off with battery light.. i beleive their was some sort of high voltage surge protector built into the dash. the issue was with the voltage regulator, which is built into the alternator... i bought a replacement at napa autoparts and installed it 2 days ago, problem fixed, truck running great since!

Thanks for the help.

Bill · 08-28-2009, 12:16 PM

Good to see you have it going, from your troubleshooting techniques I don't think you needed my advice, but glad to thro in my $50.00 worth.

08-24-2009, 09:50 AM	#1
granger Junior Member Join Date: Aug 2009 Location: Canada Posts: 2	battery light comming on/off - vehicle voltage seems fine Hi Everyone, thanks in advance for any help.. i have 2008 Ford Ranger 4.0 4x4 72000km, bought new last year.. the other day driving on the highway random dash lights started coming on and off, the abs, e-brake, airbag, and battery light would alternately flicker on and off... eventualy that stoped happening and now all that happends is the battery light comes on for a bit then goes off.. usualy when it comes on, all the gauges completely stop working... it has never lasted for more then 1 minute. i havn't had the chance to test the voltage WHILE the propblem is occuring.. but when the vehicle is idling i get steady 14.2V at the battery and at the cig lighter outlet, even after i turn on headlights on, interior lights and everything i can think of it goes down to about 14.1V. when the engine is off i get 12.9V.. i checked the alt belt to make sure it wasn't slipping and it seems fine... sounds like a bad ground to somewhere to me... not sure how to check that something interesting is i changed the oil 2 days ago and droped a bti of oil in the alternator by accident.. i also cleaned the inside of the engine bay with spray cleaner and paper towels.. but i have checked everywhere i cleaned and nothign seems wet or loose... coincidently the issue started right after this.. Any thoughts???? Thanks.

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08-27-2009, 04:06 PM	#2
Bill Member Join Date: Feb 2009 Posts: 79	Would think something is going goofy in the alternator. The alt light circuit puts power to the bulb and grounds in the alternator to complete circuit and hence light is on. As alternator charges, the former ground circuit becomes powered up and hence the bulb having power on both side of it, cannot light, (no current flowing). It might clear itself but if under warranty let them handle it.

08-28-2009, 09:58 AM	#3
granger Junior Member Join Date: Aug 2009 Location: Canada Posts: 2	Bill, you are absolutely correct, the problem has been resolved now. i rigged up my voltage meter to a cigarette lighter plug so i could monitor the voltage as i was driving.. as i would accelerate and get into the high RPMs the voltage would spike up to 16-18V and the dash would turn off with battery light.. i beleive their was some sort of high voltage surge protector built into the dash. the issue was with the voltage regulator, which is built into the alternator... i bought a replacement at napa autoparts and installed it 2 days ago, problem fixed, truck running great since! Thanks for the help.

08-28-2009, 12:16 PM	#4
Bill Member Join Date: Feb 2009 Posts: 79	Good to see you have it going, from your troubleshooting techniques I don't think you needed my advice, but glad to thro in my $50.00 worth.