Hey fellas

 

Started diag on a battery drain today.

Seems when I disconnect the alternator the drain goes from 480mA to under 50mA ........ how do I determine if I have a bad ground on alternator an open circuit ..... or just a bad alternator.

 

John, one of your pictures showed the batteies isolated. Far as your 140A fuse issue, if you mean you diconnect the wires then check for draw at the battery cable? Like Ed said, you need to keep working on isolating the circuit that has the draw on it.

Good idea ..... apart from having the battery tested how else do I test the battery for cell leakage at home ?

It will gradually drain itself due to having a small internal short in the plates basically, just monitor the voltage over a day or two and see if it drains down if you have time or don't want to pull it out.

 

If it is straws you want to grasp for look at added options first, aftermarket stereo, alarm or security system or things like that that have internal batteries or even something as stupid simple as a phone or other charger that has lights or indicators on them or anything else plugged into the cigarette lighter that is a good one for slow drains on batts, sattelite radio radar detector literally anything. I had a brake controller on one of my pickups get sticky and I didn't notice the led light was always on under the dash and every time I went to start it once a week or so it was dead or very low, like I said start with stupid simple first.

Good thing you are not paying by the hour for the repair, remember always start at the source and then look at / for obvious things first and then start isolating next when it comes to electrical gremlins it will make life more enjoyable and less stress full in the long run.

 

Another good spot for slow drains out of nowhere, did you do any recent repairs and have anything apart and back together where a wire could have gotten slightly pinched this will often cause a slow drain but not enough to blow a fuse. Wires going through the fire wall without a rubber grommet is a good one.

Too much going on to spend any time on it ...... will update when I know more

Thx

Dont know if this helps ........ but I totally disconnected the driver ground cable (which is ground to frame, block and truck bed ) and then bridge from positive to Alternator wire 140A ...... no draw.

That will be difficult to isolate. Just pull fuses 1 at a time. Should take about 15 minutes.

Ed

Already have.

Pulled every fuse in cab as well as main fuse panel .... also relays ....... no change

The only thing that makes sense to me is  I have an accessory that is grounded into frame. Thats why when I remove the negative cable the circuit breaks.

Problem is I dont think its fused into the regular circuit - as puling every fuse doesnt break the circuit.

So Im not sure how to test a circuit ....... kinda feel like I either need a tool like a powerprobe (would this show all live circuits ?) or start pulling all grounds for accessories whilst checking draw.

For giggles, have you pulled the grid heater solenoid wires? Any large audio amps? Cell charger or the like? It's most likely going to be something that you will smack yourself in the head for once you find it.... Been there, done that. The newer Power Probe will surely be nice, but in this instance, will do no more than your multimeter.

 

Ed

You can see what I'm doing here.

All accessories are tied to red battery cable which is not connected to battery.

When I probe from battery to the 140a studs with ALL alternator and FSS wires removed ( so only studs showing i remove those 4 wires in pic) I still get 0.5a draw.

Removing fuses made no difference. Both in PDC and in cab.

This is still where I am thinking the problem lies. On the 140A fuse there is one large red wire and one small(er) black wire on the same post. The large black wire comes from the alternator, the large red wire charges the batteries, but where does the small(er) black wire go? If you pull the red and black wire off the stud what happens if you go to the smaller black wire and what happens when you go to the large black wire?

Smaller black wire is the airdog harness .... which has its own 20A fuse. Pulling the 20A fuse results in no drop. Pulling the black and red wire off the left terminal still has ~0.4A draw between battery terminal and left 140a terminal.

Not the interior or hood lights

Not grid heater

Not radio or amps

This might help john.  Mike posted it but I think you can use it on your computer a little better.  https://www.dropbox.com/sh/jzn2j9hq9wfgnoc/AACWmZ04POv0Mpdgv0U8Bhfha/Engine?dl=0 Click on 2002 wiring diagram, download it and open it.  Page 28 and 29.  You should be able to look at see how to isolate it.  You mentioned you disconnected ground which breaks the flow.  Electricity has to flow from one pole to the other,  you can't get anything with just 1 pole hooked up.  Thats why you then say 0 mA.  

 

Hope some of this helps, really you just need to isolate it more.  Individualize all those wires coming off the battery terminal so you can single everything out one by one.  

 

Just noticed the fuses cut out the relays so skip pulling the relays.  I get nervous and stupid when I make videos. 

 

Hey bud appreciate the time to post that video. Here's the deal though ............ I've done about 10 different tests and yet to isolate it. I think the most accurate test (yeah the ground was a booboo) was this.

 

 

Remove the passenger battery cables so only have drivers side.

Remove the drivers postive (to break some accessories and link to passenger)

Remove ALL wires from the 140A fuse leaving just the 2 studs

Bridge from the positive battery terminal to the 140A stud ...... still get ~0.45A

Remove ALL relays and fuses and still same DRAW.

 

So ....... unless Im missing something the draw is comming from something hard-wired in. 

 

Security alarm into PCM ???

Remove ALL wires from the 140A fuse leaving just the 2 studs

Bridge from the positive battery terminal to the 140A stud ...... still get ~0.45A

This is not possible UNLESS there is some kind of foreign substance on the fuse. If you pull the RED wire that runs from the battery to the 140A fuse, you have no power draw to the battery cable?

I can shoot a video  

I believe you took the terminal off the positive post and took all the wires off the terminals on either side of the 140A fuse, then bridged it with the multimeter, thus powering the PDC.  There are 2 runners underneath the PDC "matrix of fuses" just like in a breaker panel at home.  They connect to one of the posts and kinda loop around to the other bus bar at the other end of the PDC.  So it would be Generator---140A Fuse----Battery/PDC Bus/Everything Combine.  So if he has no wires running to anything and bridges the positive terminal to one of the 140A lugs, he is powering the PDC.  He can take the 140A fuse out and he'll find that one side powers it all and the other post does nothing as it just serves as a connection point.  

 

This is purely going off memory but I'm pretty sure thats what lies beneath the PDC fuse panel when I took mine apart.  I don't think the PDC bus can be disconnected from whichever lug runs it, I think it is all one big bus forming straight into one of the lugs that you bolt the wires to. 

 

I'd leave everything disconnected, take out every fuse in the PDC (mark the empty slots first), then bridge the connection like I show in the pic (leave alternator wire off, leave them all off).  Nothing should be connected so you should have 0 amps.  Then put every fuse in one by one, watching what the multi does.  You'll find the culprit.  Let us know if you have the load even with all the fuses out.  

 

Here's a pic of what he has going on (I'm assuming) and how its making things work. 

 

Yup that looks right and sounds right. How do you mean pull every fuse out of the PDC ............the PDC is the circuit with teh C1,C2,C3 harness connectors ............. where are the fuses - under the main fuse box ?

Never mind was thinking PCM.

 

So you mean still to remove all fuses ??? Not sure - have done this. 

 

Is it possible for the security system which seems to have a ground wire going to PCM to be drawing 0.4A ? Dont know how to isolate that though.

Edited December 7, 201410 yr by JOHNFAK

Or pull them one by one, looking and putting it back.  Whatever you wanna do..  

 

Not sure how the security is hooked up but I'm assuming one of the fuses will run it.  And yes I mean the fuse box on the fender.  Everything should distribute from there and be fused in there, therefore if all the fuses are pulled, nothing should be on at all.  

 

If you've done this exact thing just as I described with everything unhooked (thought you didn't unhook everything), then I would be tracing that security system.  

Didn't   jon  say he did this,  and still had  a draw?  If so,  I'd  think  there could be   something  bizzaro  in the  pdc,   UNLESS  there is  another unfused  circuit, (not  fused  @ pdc)  but  downstream somewhere.

1000%  sure of  any aftermarket  mods  not  drawing somewhere?  

.4 or .5 amp  is  what?   a small bulb?

I  kinda  agree  with   wildfree... and  the  'fighting batteries'  scenario..

Edited December 7, 201410 yr by rancherman