Hey first post, always seem to end up on these boards for some reason or another and have always managed to find an answer but I'm having a hard time with this one.

I recently just traded for a 99 F150 4x4 Auto transmission and manual 4x4 shift. It has the 4.6 triton in it. As far as history it seems like it had been abused pretty well. The motor was completely covered in dirt, the air filter I don't think had never been changed I've never seen anything that dirty. The battery was dead on the lot but the dealer said he'd put me a new one in it. Which by new one he just took one out of another truck on the lot.

Anyways after turning on the radio on the ride home, when I got home I noticed the radio wouldn't shut off when I turned the truck off and open and closed the door. So I tried pulling the fuse and best I could tell I pulled the correct fuse but the radio still kept on going. I ended up just unhooking the radio. After our snow storm subsided and some reading I sprayed WD-40 in the doors and hooked the radio back up and now the radio shuts off when I turn the key off. Soo I assumed I found the drain on the battery.

All as been well for about a week, I drove home from a funeral last night the trip was around 160 miles. We got home around midnight, and this morning by 11am the battery was dead. something drained the battery in that short of a time. I'm going to have the battery checked tomorrow, I checked the alternator myself this evening once I got the truck jump started. This morning is was right at 12v, after getting the truck jumped off with headlights and heater on I was drawing around 14v so I don't believe it to be the alternator.

I suspect it could possible be the GEM? or I also have the odometer short I can tap on the dash and make my odometer go in and out. Would that possibly drain the battery that fast? I have checked my relay for the battery saver and it appears to be good, it clicks when I apply 12v source to it and rings out with my multimeter. Also the fuses for it appear to be in good shape too. I'm completely lost on this, the only thing I can think of is the battery is bad. But that wouldn't explain the issue with the radio would it?

any help would be greatly appreciated,
Thanks

 

What you need to know is after starting, the voltage should go as high as 15+volts to recharge the battery, then reduce as the battery recovers.
The running voltage should be in the 14.1 to 14.5 range.
It you don't see this action, the Alternator is not putting out enough.
An alternator with a bad rectifier stack will drain the battery after shutdown and over night depending on how bad it is.
A hint as to if this is happening is to feel the alternator case after the motor has cooled. If it feel warm, it has the problem (the drain).
You may well have some other issue adding to or causing the drain but do check this out first.
Good luck.

 

Thanks I'll try that in the morning. I forgot to mention there is a slight noise coming from the Alternator area, to me sounds like a bad bearing which again led me back to the alternator. Could also be the fan I guess, can't quite place where the noise is coming from.

Ok so decided to try it tonight, I ran my truck alittle to charge the battery tonight. The valve pan cover is barely warm at all but the housing on the alternator is very warm. It's not hot but you can certainly tell it's warm.

 

The alternator will get hot producing power to force current into the battery.
That's normal along with the engine bay heat.
It's after everything cools that the alternator should cool with everything else.
If it does not, the battey is draining back into the alternator and to ground.
A bad bearing can also add heat to the case.
Good luck.

 

Search odometer blackout for the odometer problem, its an easy fix

 

ok so went out and checked it again this morning and it was ice cold. Don't appear I have the drain on the alternator. So then I took my meter and started the truck and put my meter to it and was ready steady at 14.78v

It's close to 15v but not quite, is it possible my alternator is weak and not went out yet.

As for the odometer I wasn't planning on fixing it yet, I have to install a new blend door and was just going to fix all dash related stuff when I do that, BUT if it shorting out would be causing the drain on the battery I might just have to bump that up on my to-do list

And of course the ole lady has stuff for me "to-do" today so I don't know if I'll get by the auto parts store to have my battery checked. Also to have them check the alternator would I have to have it off the truck or could they check it while it's still on. I've never had them check one before, they just always flat out died on me in the past.

Thanks for all the advice so far

 

Have you done a battery parasitic drain test yet?

 

So far your observations look ok for the charge circuit.
Now it's a wait and see.
If you have a problem again, do the checks again to be sure and keep going toward some other cause of drain.
Don't rule out the battery with a bad cell.
Usually cold cranking will begin to be slower as a sign.
Good luck.

 

I have not done this yet, I feel like I need to do it. Outside of it being a bad battery I don't know what else it could be.

So am I understanding correctly for the parasitic drain test?
Let the truck sit for 30-45 mins
with multimeter pull fuses and check amp reading on battery?

any tips on how to do this with out opening the door? I'm a big guy and my fuse panel is well you know basically in the floor. Or do I pull fuses on the outside box?

why oh why couldn't it have just been the alternator haha

 

I believe opening the drivers door and manually closing the door latch will turn that door's switch off so it thinks it's closed.

Check your private message box.

 

I got the instructions, thanks for that. Will try that tomorrow and see if I can atleast locate the drain.

Only thing I not sure about in those instructions or the pictures that threw me off, is he had alittle yellow wire going somewhere and I couldn't tell and all that he mentioned was just hooking up in series.
So when I'm checking the amps initially all I need to do is connect my meters negative lead to the negative battery post and the positive lead to the negative battery terminal/cable is that right?

 

taking the battery cable off and putting an amp meter between the cable and post will record any amps flowing thru the battery at that time.

 

He just installed a tiny jumper between the neg battery post and neg cable clamp. This is so not to loose voltage when disconnecting the cable from the battery post in order to connect the amp meter in series. Some vehicles have anti-theft radios that need an unlock code if voltage is lost, before the radio will work again. You also loose KAM if battery is fully disconnected.

How to Find and Stop Car Battery Drains – DIY Car Battery Drain - Popular Mechanics

 

ok guys sorry I've not updated in awhile but hadn't had the chance to test the drain. I just did but I'm going to wait about 45mins and try again, I didn't pay attention to my hood light when i first did it. But my initial findings are,

I had a drain of 155-160mA and that dropped when I pulled the #15 fuse which has the following listed in the manual:
Stop Lamp switch,(speed control,Brake Shift interlock,ABS,PCM module inputs), GEM module, RABS test connector.

now out of all of that the only thing I know how to find is the GEM module. I had a feeling it would be something with 10,000 things wired to it.

Will update again here in a hour or so if the results turn out to be the same.

 

ok so update, after unhooking the under hood light and retesting bout an hour later this is what I found.

initial reading : 170mA
pulling the battery saver relay or fuse #14 I got 063.7ma
and pulling #15 as well took it down to 05.05mA

I wonder and hope maybe my battery saver relay is bad? looking through the manual the #14 fuse controls my 3 interior relays, the battery saver, the ACC and i forgot the other one but makes me wonder if one those 3 is bad. I tested the battery saver and could get it to click when apply 12v to it so I assumed it was good but we all know what happens when you assume haha