Hello guys I have spent most of the day today ready in doing simple test and can find a lot of things that fit a few issues but nothing that fits it all right, so I'm hoping you all can help. Here is the run down of*events*so please bear with me and the long winded scenario.*

Last Sunday afternoon we were pulling our boat home running about 65mph in tow/haul mode when the truck seemed to downshift out of nowhere to what seemed to be 1st gear. It only lasted a few seconds and went back to normal. During that time, I could hear relays ratcheting from the*fuse*panel*below and thedoor*chime*was going off as though there was a door open. The truck seemed to go back to normal just as fast as it went bad. We drove another 2 to 3 miles and it did it again. Worse this time as rpm's all the way to 5k. I quickly shifted to neutral which seemed to normalize everything except the ratcheting relays. Once I pulled over I put the truck in park which stopped the*relay*click. Put the truck back in drive the clicking would start again and the truck would lurch like it was in and out of 3rd gear. Shut the truck off thinking I was going to reset it and upon trying to restart, it would not crank over the first 2 tries, then started up normal. I let it idle for about 2 hrs before trying to move again. This time no noise from the relays and no lurching but it feels like*torque*converter*fully locked up in second gear. I decide to wait for the tow truck to arrive. In the mean time I decide to turn up the radio but can't get any sound to come out. I do have a full*jl*audio*system so I look to see if they have power and they don't. I popped the hood and check the fuse which is fine then check to make sure*battery*cables are good. I then get back in the truck and now have lost the instrament cluster and the radio.*Interior*lights*and hvac still seem to work though. Three days later I get the truck from the tow company and the*batteries*are completely dead. I charge and load test them both, one I just had warrantied last week. After charging the passengerside*battery*I*unhook the drivers to charge. I then get in the truck and pull codes with my*autoboss*scanner. To be honest I have never seen so many codes before, but a lot of them were low voltage codes. I then start the truck as normal let it run for a min, check radio which seems to be working fine now. After a few minutes gauge cluster stops working along with the radio so I shut the truck off. I tried to pull codes again and now the scanner says no communication with ecm. I can however*read*gem, security,abs ect. I load test the*passenger*red*top*battery*which is 6 months old and it fails. Replaced today and now we're back to no crank scenario. Clusters now working again but dash light are not shutting off like they normally would. When I turn the key to try to start it, the cluster and radio shut off but there is no sound from*injectorsfuel*pump*or starter I can spin the starter over with the yellow wire on passenger side but the truck does not start. I have unplugged fan,*glow*plug*relay, neither made any differance. I have looked at*wire*harness*toficm*and don't see anything there either. All fuses/relays in cab have been checked are are good. Any help would be appreciated as this one has me good.*

Thanks
Mike

 

Sounds like you're draining your batteries to operate the vehicle with a bad alternator. While running, what voltage are you seeing at the alternator rear terminal or at the pass battery. Expect to see 14.2-14.6 and alt, 13.8-14.2 at the battery.
Sometimes, you're alt brushes will start to go bad and only work when the alt is cold. After running a bit, the flow of electricity will cease and those batteries can only handle so much driving as there's so much draw and demand. The ficm needs 46-48v, 4 times your battery voltage, and without charging, not a good result.
A pretty easy replacement process.
Let us know?

 

Thanks for the reply. It no longer will turn over and I have replaced both batteries. I no longer can read the pcm or the gem module with a scan tool. There has to be a short somewhere. I can read the hec codes and after resetting it keeps setting the same 4 codes. Is it possible that the trans range sensor could be shorted out of the cluster itself?

Thanks
Mike

 

PM Mark Kovalsky the tranny guru. He is always there to help. Right answers too.

 

Will do thank you!

 

If you haven't yet pulled the alternator to get it bench tested, I would. Your entire issue could be just and only that. Keep us posted!!

If you do need another, I'd suggest taking the opportunity to upgrade especially considering your audio system. Of course, you're surprised to see that we carry alternators.

Alternators