Hey all ,

I run an edge insight cts and i monitor battery voltages as well as other things but am worried about my volts ...I have been having issues with batteries getting drained if truck is not started and ran within a 48 hour window ...something is draining batteries but no lights are on ...just the blinking light from my viper alarm ..This battery issue has been going on for a year but now is really starting to get worst ....I changed batteries when thr problem inisually started but did not resolve the problem ...I have been noticing my ficm voltage has been low (38v) when i 1st start truck but will increase to 47-48v as truck runs for a few minutes ....The edge insight reads data from OBD2 port ...Just today i got my truck washed and all was fine until i got home ..i was idling in my truck when radio started to freak out (turning on and off kinda ) and at that point i noticed my voltage was at around 9.5 on my insight and dropped to 8v before i shut it off ...needless to say she is not starting ..i used to just hit the throttle to about 2500 rpms and the voltage would immediately jump back up to the 13-14v mark on my guage .Also noticed that the ABS light on dash came on when volts got low ....So the questions i have are this ....

1...Where is the OBD2 port reading its voltage from ?

2...Anyone else every have this problem and if so what happened ?

3... Any suggestions at all about this problem ?

I hope i gave enough info because im stumped ..i hate just throwing parts at her but i think i have 2 issues here and one of them may be an altenator but not 100 %

Please help !

 

I would say your alternator has gone completely. The OBDII gets it's voltage reading from the computer, which itself senses it from a power bus somewhere, and converts it to a data point that can be read by the OBDII scanner you have. The odd readings and radio stuff were what happens as the voltage gets too low to run the dash, and the radio. The FICM power level at 38 volts is what happens when the FICM fails, in this case probably due to the failed alternator. I would get the alternator working again, get the batteries load tested and verified perfect, then see if the FICM comes back - it probably won't and you'll need to change that or get it repaired.

Brian

 

your voltages indicate low charge rate and bad ficm , but before you come to any conclusions you must fully charge your batts with charger then have them load tested . chek and clean batt conections and grounds . also check conection at alternater this is often a problem . your obd port moniters the volts which computer sees. poor conections bad wiring could affect volt readings so suggest reading volts with meter at alt and at battery(s) good luck

 

Since pulling the alt is a 5 minute process that involves removing 3 bolts and a couple wiring connectors, I'd pull that and get it tested while the batteries are getting charged.

Grab the belt with a hand on each side of the alt pulley and lift straight up, it'll lift up right over the pulley. Or you can pull the wiring connectors, remove the front alt bolts, and let the alt tip forward as you pull the rear one out.

 

You don't give us much info on your truck, but from my reading on some of the alternator threads here: if your truck didn't come with either the factory high output or dual alternator set-up, then yours is the standard 110 amp one. Most tend to believe it is way under-powered to run everything on a 6.0 and also fully charge the batteries.

I'd figure out what alternator you have and consider an upgrade if that's the case...

 

Thanks guys ,

Im going to charge the batteries and take alt to auto store and have them test it ....The thing that stumps me is the batteries loosing voltage within 24-48 hours ...

 

Yes my truck is pretty much stock ..i run a custom tune from eric but thats about all ive really done ....Shes up to 140,0000 miles so its probally about time to get dirty ...I was thinking of upgrading , i know autozone and advanced carry a 140amp model or if i want to wait till tomarrow i no a shop that rebuilts altenators and they can get me a 200 amp alt if need be ...would 200amp be to much ?

 

Not from what I've read it wouldn't. Especially if you run a big stereo or other high draw (winch, plow, etc.) accessories. We have the factory 140A and heated seats but stock radio, charge the trailers or camper, etc. depending on what we're up to, and it has worked fine. I am just collecting some scanning/monitoring gear and will be checking FICM voltage, but another indicator is our factory batts lasted 6+ years (infact only one was part down the other was fine).

I forgot to comment on the power drain: some years back I traced an electrical leak back to the a/m alarm. and I hate to say it but it was a Viper... Good luck on that part.

 

I wouldnt doubt its the Viper alarm ...im gonna have to disconnect it and see if it helps ...Only problem with that is i might not have a truck in the week i have it disconnected ..especially in wonderful south florida..ugghhh ....I dont have any accessories and just a stock radio ..it is a king ranch so it has every bell and whistle and also a sunroof ..I think 140a should be fine but if ya all think i should upgrade to a 200a alt i will ....lol ...

 

If you're really that worried about the truck walking away in that short time period, start pulling the FICM relay out from the junction box under the hood. It'll stop casual thieves who don't carry wiring diagrams around of the trucks they try to steal.

 

Good idea ... i already have jimmijammers and a manual fuel cutoff switch i her besides the alarm so they wont get far if they drive her ...my last truck i had for 6 days and she got stolen ...so im alot more cautious nowadays ..

 

Bad thing about that is it's extremely hard on the injectors.

 

If your drain-down is happening that fast, it would only take overnight to see a significant voltage drop. Or to speed the process of elimination up, one idea, not saying it's the best I've had just because it could be hard on one battery: is to fully charge them, disconnect one battery and disconnect the alarm. The other battery will show a greater drop (quicker) than two in parallel. Then start eliminating other components the same way if the alarm turns out ok.

I don't think you need any more than a 140A alternator. I've run a dump trailer that I constantly have to charge off the truck (it does have it's own deep cycle), and like I say, we've been fine -- just lacking your sunroof but otw ours is a Lariat and has power everything too...

Good luck!

 

well heres an update .....

Found out 2 batteries were bad ..they are under 1 year old and were not good under load test ...Replaced 2 batteries ..

Ficm was going bad ...Took it apart and resoldered and now shes sitting at a steady 48v and good to go for the moment anyway ....

Will keep informed on voltage being low after truck sits for a few days ...hopefully it was just the batteries and something isnt killin my batteries ..ill keep up to date with any info i find ..

Thanks to all that chimed in ..

 

Well shes all good now ....musta been those crappy advanced auto parts batteries ...Just to show ya that paying 130 bux a peice for a battery doesnt make it better ...lol ....Ficm still sittin steady on 47.5 -48v ....Very simple fix to solder it thanks to the knowledge on these sites ....saved 150 bux by not havin to go to international for a new board ..