Intermittent batt light

[Leroy88]

Ok here goes, 02 7.3L PSD. One new batt, one replaced in january. Alternator replaced with new one one month ago. On startup at cold idle no light reading 14v on batteries +/- .02v. When driving at some rpms , it varies, the light will flicker on and off. Brought alt to store tested twice and passed. Ideas?

[bigcountrysg]

When does the light come on. Is it at idle?

Also when replacing batteries you should replace in pairs. Replacing one at a time only causes the new battery to prematurely wear out. Also it can cause the alternator to fail prematurely to.

[Leroy88]

Ive only seen the light at idle two or three times. Upon first start up of the day at idle no light. When accelerating it flickers on an off from as low as 15mph. Depending on cruising speed, it may be strong steady glow or may lightly flicker. I saw constant glow at 60mph and 45mph this a.m. Then I stopped at a red light and it went off. Upon accelerating it came on, reached 45mph cruised for a min or two and went off conpletely the rest of the way to work 5miles roughly. Got to work, stoped to scan in, acceled into yard and no light. Parked and idled for 20min no light.

Yes I know you should replace in pairs but cash is tight so one thing at a time, not gona buy another new batt if its 6months old and still perfect.

[dzldawg59]

I just joined the forum for this reason. I installed am aux fuel tank and electric pump. Just after that I got the "flickering" battery light. I took the truck to Autozone and there computer found the a bad alt. Changed alt, problem continued. re-tested alt at AZ. Alt tested good. Had batteries tested (Sears DieHard) Tested good. Battery light is now continuous. Sears did an alt test and found that the alt was only putting out 9 volts. Next plan is to pop the small plug on the alt (as seen in another post) and see if the light goes out. Then back to AZ for another alt test.
Stay tunes...

[nccatfan]

Checked ground connections?

[dzldawg59]

I just joined the forum for this reason. I installed am aux fuel tank and electric pump. Just after that I got the "flickering" battery light. I took the truck to Autozone and there computer found the a bad alt. Changed alt, problem continued. re-tested alt at AZ. Alt tested good. Had batteries tested (Sears DieHard) Tested good. Battery light is now continuous. Sears did an alt test and found that the alt was only putting out 9 volts. Next plan is to pop the small plug on the alt (as seen in another post) and see if the light foes out. Then back to AZ for another alt test.
Stay tunes...

[dzldawg59]

I just pulled the 2 wire plug of the alt and the light went out. Plugged it back in the light went back on. That tells me it's an alt issue. back to autozone.

[dzldawg59]

Autozone tested the alternator and said it wasn't putting out what it should be and gave me a new one. No more battery light. Leroy88, try pulling the 2 wire plug and see if it turns the battery light off.

Thanks for all the help guys,

Mike
02 xl 2wd crew, 7.3, de-restricted exhaust.

[jbeasts10]

Originally Posted by dzldawg59

Autozone tested the alternator and said it wasn't putting out what it should be and gave me a new one. No more battery light. Leroy88, try pulling the 2 wire plug and see if it turns the battery light off.

Thanks for all the help guys,

Mike
02 xl 2wd crew, 7.3, de-restricted exhaust.

glad to see you got your problem fixed