Ok tested the battery and alt yesterday. The battery is bad yet still starts the truck no problem but seems to only have 100% charge right after I shut the truck off. If I let it sit for awhile it drops to about 50%

 

Oh and the alt passed including the diode test.

 

Sounds like the battery has a leaking/shorted cell, if the alternator has passed all of its tests. Don't know how you've tested things, but just to cover all your bases, disconnect the alternator & battery B- cable, charge the battery, then let it sit over night & see if it'll hold a charge with everything disconnected from it. If not, it likely has a leaking/shorted cell & needs to be replaced.

If it holds a charge overnight, look to a leaking/shorted alternator diode, faulty electrical equiptment, or wiring problem with something in the vehicle, like a lamp thats not turning off, stuck on brake light switch, or maybe the GEM isn't timing out & going to sleep like its supposed to after about 20min, or maybe an acting out piece of add on equipt.

More thoughts for consideration.

 

I'll give that a try thanks.

 

Now I've been testing it at work with a "battery tester" but is there a way that I can test it at home?

 

With the battery B- cable disconnected, if you have removable battery caps, you could check each cells specific gravity over time & determine which one is acting out. If its an internal battery cell problem, the acting out cells specific gravity will change.

Likewise if you have a multimeter, you could check the fully charged battery no load voltage, then check it every few hours to see if its dropping, which would indicate an internal cell problem.

Or with the battery B- cable disconnected, rig your multimeter in series with the B- cable & battery B- post to monitor parasitic load current in amps, to see if the GEM goes to sleep, or if something else is drawing too much current & causing the battery to discharge.

 

It's an optima so no removable caps but ill try the rest.

 

After a half hour the GEM should go to sleep & the parasitic current should drop to 50ma or less. If it stays up around 100ma or higher, the GEM isn't timing out & going to sleep, or something in the vehicle is acting out, maybe an add on electronic device, or one of the other listed things to check.

Did this problem come about suddenly after some event????

 

Not totally sure but I vaguely remember testing it once before and it saying it wasn't fully charged but can't remember for sure.

 

Ok totally unrelated question. How do I go about testing my "purge valve solenoid" (assuming that's what its called)? Its the one between the canister and the throttle body. It doesn't seem to be letting much through. I used a pair of jumper wires and connected it to 12v and it doesn't seem to be opening all the way and doesn't seem to be opening at all when hooked up and plugged in properly. also how do I test the wiring to it?

 

When the truck is running without it plugged in it has no complaints, the CEL doesn't come on or anything so could I just bypass it? When I bought the truck the filler neck was all messed up so I rigged one up but now it's leaking again at the tank so I just figured maybe it built up to much pressure and made it pop loose.

 

Joe, Im again having problems trying to follow what your thinking & doing in your posts.

Back on the 12th you were gonna disconnect & charge the optima battery & leave it disconnected overnight to try & determine if you had an internal battery problem with a cell self discharging. Then if that was ok, you were going to hook up your multimeter in series with the disconnected B- cable, wait a half hour or so, to let the GEM module go to sleep, then measure what your parasitic drain on the battery is, to see if excessive parasitic drain from something else was discharging the battery overnight, SO, what were the results of those two tests?????

Then yesterday you began talking about the purge valve solenoid, then today saying the engine runs ok when "its disconnected", but we don't know whats been disconnected???? If it was the vapor canister purge valve that was disconnected & the fuel intake fill tube is leaking at the tank, it'll mess up the vapor recovery system operation, so you need to get that whole end of the assembly replaced/put right, so things are working as designed, so the computer doesn't get as confused as I am about whats going on!!!! lol

 

Sorry about the delayed response. I took out the optima and put in a spare that I had, then took the optima to work to test it. It did seem to hold a charge when I tested it at work out of the vehicle and the spare I put in also showed a low charge after the truck sat for awhile. So there's definitely something discharging the battery. The only two things it could be is the yellow wire going to the alt or the e-fan I recently installed. The fan doesn't run when the truck is off so I don't think that's the problem so on my next day off I'm going to see what I can do with the yellow wire to fix the issue. Now as far as the purge valve goes, when the truck is running the wire going to the solenoid has power but when it's plugged in it doesn't seem to be opening. It was still under warranty so I swapped it out. That didnt solve the problem. So I bypassed it using a piece of vacuum hose.

 

Also just the other day my check engine light came on while I was driving. When I tried to read the code it didn't show any. It seems that it comes on when I'm driving then when shut the vehicle off it goes away and doesn't even show up in the history.

 

OK, you now believe the vehicle has excessive parasitic drain, so with the engine off, disconnect the battery B- cable at the - battery post & connect your multimeter with it set on the 10 Amp DC range, in series between the disconnected B- cable & the - battery post.

Fasten the multimeter + lead to the disconnected battery B- cable & the multimeter - lead to the battery - post & note the parasitic drain current.

Then check it say 45 minutes later, after the GEM times out & puts everything it controls to sleep & the parasitic current should drop to say around the 50ma range, depending on how many electronic things with memory, you have plugged in on the battery circuit.

Things like stuck on brake light switch, glove box, trunk, under hood, or dome lights, clocks, radios, phones, CD, or tape players with memory, or a stuck CD or tape in the player, CB or short wave radio, or other after market electrical/electronic equiptment, can cause the system to draw more parasitic current, so be sure to check out All that apply, to make sure their off line.

A leaky or shorted alternator diode can drain the battery.

If after say 45 min, the parasitic current is around 100ma or more, begin inspecting the above things, maybe begin to pull fuses one at a time, to try & determine which circuit has the most parasitic current draw, then begin a systematic inspection/disconnection of all electrical items on that circuit.

On the CEL that comes & goes, it suggests its an intermittent problem, like maybe an old lazy O2 sensor would cause, or maybe a misfire that corrects itself, ect, but you should have a "pending" code stored in CM for a number of drive cycles, if the CEL has been lit, so be sure to look for stored "Pending" codes.