battery light on...?

[charny74]

my battery light has been coming on and off for the past 4-6 months and it is staying on longer now in the past few weeks. i havnt check my battery reading yet with the truck off but i take it this means either the batteries or the alternator are going bad. How could i find out if the alternator is going... or is there another component that i am neglecting to consider. I dont have my owners manual so i cant look in the trouble shooting area. Thanks for any help

[jbdawson]

Measure the voltage with the engine running. Should be 13.5 to 14 or so. If lower than 13 probably alternator problem.

[Ford_Forgotton]

999 times out of a thousand, battery light = bad alternator.

Bad batteries can take out your Alt too, so when you put the new ALT in, have your bats tested to make sure they dont ruin the new alt.

replace batteries in MATCHED pairs only.

[charny74]

well now im dumb founded. checked the right side battery and got 14.1 or so volt reading. i guess ill check the other as well but i would think its all the same. That was with the truck on. There is a wine coming from up front and i figured it was the alternator going... im gettin wurse fuel milage than normal so i figured it was giving more resistance to the front belt this effecting milage... now i feel like im back to step one but i still have that darn light on.... what the heck

[Ford_Forgotton]

You may be getting 14.1 VOLTS, but you may not be getting full AMPERAGE.

Checking one battery is the same as checking the other so long as both batts are still in the truck. They are paralleled.

But, as I stated above, 99 times out of a 100, its a bad Alternator if the BAT light is on.

[IndianaDave]

[ QUOTE ]
999 times out of a thousand, battery light = bad alternator.

[/ QUOTE ]

Listen to what he said. Change your alternator.

Do not drive your truck again until you do or you'll be asking "what is the best battery to buy and why" next.