I got a duesy for the experts. Im new to Fords so im still figuring it all out and need a little help please.

I have a 2000 F250 V10. I bought it not to long ago and she has never given me a problem. Until i wasn't paying attention and hooked my battery up backwards.

Only for a few seconds. The truck was not started and i immediately removed the cables and put them back properly.

Right after i was driving to town and noticed the battery gauge was at 18 volts. I went straight to auto zone for a test. Popped the hood and the battery was boiling hot. Battery tested good, alternator passed but the guy said the starter failed.

Not really believing that i decided to head home to do some research. I noticed the battery gauge climbing high again so i pulled over to let things cool. Figuring i hurt the battery i had the brilliant idea to start the truck and disconnect the battery and drive home on the alternator only.

I went 4 feet and died.

Hooked the battery back up and cranked the motor but it would not even try to fire.

I broke out the ol dumb phone and did a bit of reading (a lot right here on the forum). Then called my uncle who is a master mechanic.

He explained that i possibly depolarized the alternator by positively grounding it. It damaged the regulator so it was throwing out as many volts as possible causing the battery to over charge. By disconnecting the battery all the extra voltage went into the electrical system and fried something

I was able to narrow the problem down to one 20 amp fuse , location 5 in the power distribution box under the hood. It is for the pcm, fuel pump, relay coil MAF sensor and injectors.

I don't even have to crank the engine. The fuse blows instantly when the key is turned on.

Has anyone else done this? Ideas as to where to start looking?

Thanks for any and all help

 

1. Disconnect battery negative cable.
2. Connect ohmmeter between F5 load side terminal and the battery negative cable and verify short exists.
3. Disconnect the named loads one at a time until the short indication goes away to see if you've damaged the PCM, the MAF sensor, or something else. There's a lot connected to F5, start with the easiest ones first.

Your alternator is most definitely fried, but you also need to find and fix the consequence of that failure (over voltage).

 

most likely you fried the ecm and alternator.

and who ever tested the charging system..
at 18 volts . they have no idea how to test it.

both hooking up battery backwards and running without a battery is real bad.

charging system Needs a battery to know where to regulate... so goes wild without one.

my opinion.
.

 

I appreciate the feed back.

Projectsho89 i really appreciate the step by step way of tracing the problem.

Thanks guys

 

Do keep us posted as you try to sort this out, and do let us know the final outcome!

 

Will do. I personally hate it when somebody posts questions about a problem on a forum and never tell what happens.

These forums are a bank of knowledge. Cant say how many times i have been able to diagnose a problem from old posts. And when there is no final answer posted, its kind of like reading a long mystery book, with the last pages ripped out.

 

.
Thank you for understanding.
.

 

Update (finally)

Alternator rebuilt. Several fuses blown. Previous owner had wrong size fuses in certain slots (i was not happy to see 20 to 30 amp fuses in 7.5, 10 and 15 amp slots).

As of now im no longer blowing fuses and the engine cranks but wont start.

It seems that the coils are not sparking the plugs. Currently learning how to use a multimeter to test coil packs. It seems power is getting to the coils but it is not receiving the switching signal.

I also checked the fuel pressure using the valve on the rail. Barley got a dribble and i don't hear the fuel pump kick on.

Going back and forth between projects, hopefully ill have her ready for the snow!

 

if the stator winding had to be re-built then odds are that your rectifier/regulator is shorted out....typically located in the ECU

 

That's all part of the alternator. Never heard of it being in the PCM on a Ford. Not to be confused with PCM-controlled alternators of later generations (which still don't have those components in the PCM).

 

Another thing I don't understand is why my obd2 code reader can't connect with the truck. It trys but it just can't communicate.

As for the lack of switching signal, I guess I will try replacing the crank and cam position sensors. I hate just throwing parts at it but I don't know what else could be the issue.

 

Could be any number of things including a damaged PCM.

 

If the PCM needs to be replaced, what is needs to be done? Do they need to be programed with my vin number by a dealer or professor programer?

 

In a 2000 F250, it should be plug and play, assuming you match up part numbers correctly.

 

You checked the fuse for your cigarette lighter or your aux port? your OBD power is tied to one of those.