I have a 2004 5.7, here is my problem-

My battery isn't getting charged, it will start (if the battery has enough juice) and go for a bit but the whole system is running of the battery, basically the altenator isn't coming on.

A few weeks ago my voltage gage dropped dead, so I got the altenator tested and it tested good, so I went ahead and replaced the batter with out getting it tested (dumb idea I know) and the gage was will dropping. So then I replaced the altenator anyway, thinking maybe they messed the test up or something, and still voltage gage is dropping and the battery isn't charging. So I took it into a shop and they told me the pcm needs to be replaced, they wanted to charge a pretty expensive amount so I bought a pcm and installed it myself (bought it from Solo's PCMs in Miami,FL), much to my dismay this didn't solve anything. My next step was taking it to a dealership, where they've pretty much been giving me a run around. They insisted on replacing the altenator (even after I told them I already tried that), I told them to go ahead with it if it will fix the problem. But it still didn't know they are saying the PCM is bad and want to replace it, asked me to see if I had a warranty on it and could get a replacement.

I know Solo PCMs have lifetime guarantee, and could probably get a replacement, but I'm wondering if the dealership is trying to jack me around or if they are just overlooking something.

My apologies if the story is a little hard to follow, its been a big mess. Any input is appreciated.

 

Dealerships are always crooks. Instead of using their brains and fancy diagnostic equipment they want to replace parts until they find the bad part all at the same time charging you for parts you didnt need and their labor.

I vote for the PCM since it is what regulates the voltage from the PCM through the use of several other sensors like the Batt Temp Sens under the battery. I think you should click the link in my sig to download a copy of the Service Manual for your truck and go through it and see if it can help more

 

Thanks for the feedback and the link. I checked it out and might have possible found what the deal is. I appreciate the help.

 

Please come back and post what the resolution is

 

I know im late but was wondering if DrewL88 ever found the answer to his problem. Im having the same issue now in the same order minus the dealership.

 

What troubleshooting have you done, and what parts have you replaced?

 

I have sent my pcm to get reworked. Replace alternator and battery. They both have less than 5 miles on them. And I just purchased a voltage regulator bypass( https://store.alternatorparts.com/hd...saAlDEEALw_wcB ) but bfore I start chopping wire do you think that temp sensor at the bottom of the battery have anything to do with my alternator not charging the battery?

 

That is entirely possible. I have seen failures where that sensor is telling the PCM the battery is really hot, and the PCM responds by turning off the alternator. If you can, plug in with a scanner, and see if you can read that particular bit of data. (parts store scanner should be able to, if you don't have one.)

 

When you tested the alternator you probed it to the battery and read the voltage off the battery is 14.2 correct. or if you probed off the back of the alternator itself and the voltage coming off the alternator verify the alternator is sending that power I would suggest possibly jump ring with a new wire from the alternator terminal to the positive side battery and see if that at least starts a charging of the of the battery

 

You you can check your fuse locations there's going to be a pretty big fuse involved with the charging application of the alternator I think it's an 80 or 40 amp fuse check it check your fuses and relays and make sure that your fuses are all good if you're not charging I would suspect that might be an issue use a ohm meter to check resistance across them make sure that you're good to go each fuses is singing out on the meter so that you know you're good to go