Hey guys,

So im not sure why everything wants to decide to break lately all at the same time but another issue arose that im really stumped on. So i have 3 custom dash pod gauges ( tach, voltage, oil psi ) and sunday i noticed that my voltage and oil psi gauge weren't really working right so i thought, oil psi was at 0 and sometimes would spike back to around 20 which is normal then my voltage would be around 10-11 when normally its at 13-14. Didn't think a whole lot of it but yesterday night me and a buddy were making a midnight food run and on the way all my gauges went real dim with all my lights in the cab, he started smacking the gauges and they would all return back to normal ( tach, volts, oil ) but when he stopped beating them they all went back super dim and stopped working. We figured we would just check for a lose wire in the morning, continued on and got food, went to start the truck back and no go, battery was drained and reading 7 volts. Had someone give me a jump and it started right up. So we got in and went on our way home, but as soon as we left the parking lot my volt meter read back at 5-7, radio shut off, all gauges died, my speedometer didnt work, stayed at 0 the whole time, under it where it says your miles was blank, all my dash lights came on ( cel, airbag, battery, ect ) my tow button on the end of the gear selector was blinking, truck was a bit hesitant on going when i tried giving it gas although it still accelerated after a second of giving it gas. Woke up and ripped all my gauges out to find all wires were intact, grounds were still fine, didnt find any lose or broken wiring from radio, gauges or my amp. What really gets me is i hooked my multi meter up to the battery studs themselves without the actual terminals attached and it read 11.94 volts... i then attached the positive terminal from the truck to battery and volts stayed the same, but as soon as i attached the neg / ground terminal to the battery it instantly dropped to 7.4 volts and drops really quickly and steady until i pull that terminal back off, once its off it goes right back to 11.90-11.94 volts, then if i try putting it back on it drops again to 7.4. I've tried looking for broken or junk wiring but everything looks decent. Can anyone shed some light on why it would drop that much when the ground/neg terminal is placed on or how to go about locating and fixing this issue? Im completely lost on this one

95 f150 rwd xlt

 

It sounds sort of like you're saying the unloaded battery voltage is 11.94 volts, and goes down from there as soon as anything is connected?

If that's the case the battery is toast, most likely. Try a slow thorough charge for a day but if it's more than several years old it's time to shop for a replacement.

Now this may not be the source of of the problem (phantom or parasitic drain sounds like too) it may be a symptom, but a defective battery can result in some strange stuff, and damage other components too.

12.8 volts is a fully charged "maintenance free" battery at 70 degrees. Keep the battery charged up at all times till things get set right.

 

That was the weird part, the battery was brand new, only around 6 months old. i grabbed the 5 year old battery from my 4x4 and swapped that, still had the voltage leak, had a friend come over and we found that the neg/ground terminal wire where it grounded at the frame then ran to the engine for ground, where the bolt went into the frame to hold the wire down actually had some exposed wire that was resting on a metal tube that was basically running a charge through the whole frame and all components, we managed to fix that part and now the battery runs 12.4 and when running it runs 14.4 so we found the issue. Sucks though a brand new battery is shot because of this, stupid thing wasn't cheap

 

Well of course it was new - all batteries was new at one time, ha ha. /jk

No, exposed ground wire or grounding to the frame won't hurt anything. There is a parasitic leak or phantom draw and need to find it or you'll be replacing batts every six months.

The way you do that is to place an ammeter in series between a battery post and cable terminal. Old school trucks should read Zero draw, more modern trucks with security systems and radio presets and bun warmers and computer whizzernangle gee-gaws have a low, constant draw.

But it should not exceed about 50 to 75 milliamperes. A 1000 mA = 1 ampere. Set up your ammeter and let the computers and such power down, maybe 45 minutes. Then check the draw. Start pulling fuses to see what's causing the draw.

Typical problem areas are rear wiper motors that won't park properly, aftermarket stereo or security or remote start systems, etc.

 

Interesting. I will see if i cant get my hands on one of those meters and see. Volts read 12.2-.12.4 while driving and idle. Out driving for a few hours to test it all, although before this stuff happened i read 13-14 volts with the truck on which is what it should be, will be nice to find out whats stealin my power

 

Just buy one. They last forever, and are a hell of a lot cheaper than batteries, alternators, starters, solenoids, ECU, and the time and labor to install etc etc. Lots of uses around the home too. Will quickly pay for itself.

 

Yeah without a doubt, My mutli meter actually has an option for amps so i should be able to do it with that, if not then a quick store run. Youtube was a huge help on how to do the testing, if i do have a leak then im pretty sure i have a good idea on where its from as well

 

Well there ya go.

Modern trucks seem to draw down pretty fast even when technically nothing is wrong. They take a half hour to an hour for all the modules to "sleep", and during that time they draw the equivalent juice of leaving a headlight or two on. This puts the battery behind the eightball over time.

 

Gotcha, Appreciate the info and help, I knew it was leaking power just had no idea how to go about testing it. Since it decided to start pouring rain i will have to check it in the morning and post back my findings, hopefully something very simple, love these older trucks but when they do break its a pain