Alternator...no, battery...no, starter...no,...then why wont my truck start?!

[Phoenix]

Sorry for the long winded question but I want you guys to know the facts...


My battery light came on about 3-4 weeks ago and for 4-5 mins then went out. Not 10 mins later the truck shuddered to a stop. Being as how the batteries are only a year or two old, I deduced that it must be the alternator. But I had a local battery/alternator shop test just be sure. They came to the same conclusion. I replaced the alternator with a 200amp from a reputable alternator company off eBay. That was 3-4weeks ago. Everything was working perfectly until yesterday. Went out in the AM to crank the truck and got nothing but click,click,click.

Took the batteries it to AutoZone to have them checked. They charged them fully and I put them back in my truck. Truck starts fine but I wanted to make sure I didn't get a faulty alternator so I immediately drive the truck to AutoZone to have them run an alternator test to check the voltage. Pushing out 12.38volts. Test concludes that the charging system is good. I drive back home and don't go back out for the rest of the day.

Fast forward to this morning, go out and try to crank the truck....same click,click,click. All of this within 12 hours. Full batteries to completely drained. What gives? Nothing was left on. I don't think this is a fuel issue.

[Raul@Stealth Automotive]

you have something drawing the power.. this happened to me as well.... for me it ended up being the passenger heated seat... it shorted out and was staying on all the time and draining my batteries overnight

best thing to do is take it to an electrical guy and have him hook up his meeter and check for a draw.. if there is one just slowly start pulling fuses and disconnecting things until the draw goes away.. then you know its that whats pulling the power..

-Raul

[gunther_01]

I'm not sure on these trucks, but 12.38 volts is not enough if the truck was running. Mine has two batteries (I imagine yours does too) and at that voltage you are barely doing anything electrical charge wise. It should be closer to 14volts while running.

Put a volt meter on the batteries while not running. Write that down... Start the truck, check voltage.. There should be at least a one volt rise if not more.

A bad alternator can drain batteries also.

[russf]

12.38v is not enough! You should be seeing atleast 13.5v, put a DVOM on the main battery and check voltage at idle, then try at like 1500rpm+ should be over 13v. Also check with grnd lead on alternator case and positive lead on positive post of alternator and see what that is putting out. If it's not over 13v you got a bad alternator or regulator.

[ianstew]

13.5 is what is needed to charge up well, 12.3 is too low.replace your alyernator.....

[fordoffroader101]

how many volts should it read when your cranking it over? because mine reads about 10.1 volt when i try to start it.

[Phoenix]

Well, my alternator read 12.38 volts during the AutoZone test but I forgot the put the negative cable back on the main battery during the test. Would that make a difference in the voltage reading for the alternator?

[djanzen]

Originally Posted by Phoenix

Well, my alternator read 12.38 volts during the AutoZone test but I forgot the put the negative cable back on the main battery during the test. Would that make a difference in the voltage reading for the alternator?

Was the truck running when you had the cable off?? if so you might have just wrecked your new alternator!

[Phoenix]

yes it was, but the problem started before the charging system check.

[quequeg37]

anything below 12.6 volts is considered a dead battery. Do yourself a favor ad steer away from the car part chains and find a good mechanic or shop that deals with 6.0's regularly. Trust me your life will be better off if you d. Auto techs generally don't know the specifics of these trucks or any trucks for that matter