2002 F350 7.3 alternator??

[LuvNMud]

I have a 2002 F350, dual battery single altenator. Last night, it wouldnt start, had to jump start it.. going home, the abs light was on and my stereo was completely off... I am pretty sure that is the computer reserving battery power for essential use... when I got home, I disconnected the neg bat cable on the drivers battery while running.. nothing changed, leaving it disconnected, I went to the pass battery, unhooked neg and it died immediately.. In my early years, that meant the alt was bad, is that still the case? with the truck off, both batteries read 12.7 to 12.8 volts...with the truck running they both ran 12.44

I plan to take it to Autozone in the am to get everything checked, but, thought i'd ask here to see if I can get a good answer first.

thanks!

[zambonimaxx]

The disconnection of the grounds will kill your truck no matter what. With the volt-readings that you are giving though i would say its safe to say that your alternator is dead. If you want have autozone check too, but out trucks are known to eat through batteries and alternators. Is it the original alt? Mines a re-man at 120k

~Phil

BTW

[LuvNMud]

Originally Posted by zambonimaxx

The disconnection of the grounds will kill your truck no matter what. With the volt-readings that you are giving though i would say its safe to say that your alternator is dead. If you want have autozone check too, but out trucks are known to eat through batteries and alternators. Is it the original alt? Mines a re-man at 120k

~Phil

BTW
<----thanks

Not sure if its original or not, I have had it about 1 1/2 years, it has 330k or so miles.

thanks for the quick reply... I wondered if the old way of testing the alt would still work...

[zambonimaxx]

No the old way would only work with mechanical injection. All the new computer systems need battery power in order to run, which is why a bad alt is a large issue with the trucks, they can cause all sorts of gremlins, as well as shutting the truck off completely.
~Phil

[ridiculously_necessary]

test them all. its probably your alternator, but could be a battery with a dead cell. i had tha that happen. the bad battery tested fine with a multimeter but failed the load test.

[GETPHILTAFISH TOW TRUCK]

I was looking for info on why my ALT goes out every year or two and saw this and I have to disagree I just put a new alt in and started the truck, lifted both negatives off and it ran fine. I did this same test after I charged the battery with the old (bad) ALT and it died as soon as the second wire was removed. I feel this is still a valid test. I have a 2003 7.3.

I think My ALT issue is that I have been using AUTOZONE units which I used in a pinch and since they have the lifetime warranty. So be it. I just need to install a AMP and VOLT gauge to know when I am going to have problems.

[LuvNMud]

well, Alt was def bad, replaced it, about a week later, both batteries died... so, replaced those too.. not sure if age just got to em or if bad alt killed em, but, all gooder now

[LuvNMud]

Originally Posted by GETPHILTAFISH TOW TRUCK

I was looking for info on why my ALT goes out every year or two and saw this and I have to disagree I just put a new alt in and started the truck, lifted both negatives off and it ran fine. I did this same test after I charged the battery with the old (bad) ALT and it died as soon as the second wire was removed. I feel this is still a valid test. I have a 2003 7.3.

I think My ALT issue is that I have been using AUTOZONE units which I used in a pinch and since they have the lifetime warranty. So be it. I just need to install a AMP and VOLT gauge to know when I am going to have problems.

The guy at autozone said some vehs, it will kill the computer if you remove the cables while its running.. he said he knew mits was bad about it but wasnt sure what other vehs might have issues.. I know i'd be pretty ticked if my battery cable went back and I had to replace computer because of it. Bet next veh I buy I double check before I try that one! I too ended up with an autozone alt as Oreillys alt test machine was out of order, but, like you, as long as its warranted for life all well I too will be installing a volt and amp meter