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I'm not sure I understand. I know that F15 which controls GEM will drop down significantly after 40 mins. I witnessed it drop around the hour mark.
But F14 has the same behavior? What on F14 pulls power for 40 minutes?
I just checked battery voltage this morning with F14 being pulled and it has barely dropped overnight. F15 has been in the whole time and seems to be operating as expected (pulls power until after 40 mins it goes to sleep).
Fuse 14 - Dome Lamp, Cargo Lamp, Courtesy Lamps, Running Boards, Power Mirrors, Vanity Mirrors, Map Lamps, Underhood Lamps, Glove Box Lamp, Power Windows (Delayed Accessory)
Okay, you REALLY need to make current draw measurements it you want to make any real progress in both understanding the system's operation and, if a fault exists, diagnosing and resolving that fault. Battery voltage readings are not particularly useful in revealing anything other that "something doesn't seem right".
The listings in the owner's manual are very simplified. You have to dig into the actual schematics to understand what is happening. Do you have the schematics (EVTM)?
Found these diagrams on alldata, but this doesn't seem complete or 100% correct, as I believe there are more components on this fuse than what is depicted here...
So even with this, I'm still not sure exactly where to go from here. I unclipped the mirror wiring harnesses but still saw voltage through this fuse, so it doesn't seem to be the mirrors.
You could go for an inexpensive well rated clamp on amp probe. This will allow you measure current on any given wire without braking any current wire connections. The few things that I know of that brings the vehicle out of battery saver mode are, opening an unlocked door, pressing the brake pedal, using the entry keypad, using the fob remote. This is just a suggestion you can look into. I've always preferred a clamp on instead of using a meter inline to measure current/amperage usage.
So unfortunately I think I am still not sure what is going on. The fuse has been pulled for a few days. It's been 24 hours since I last drove it, and the battery is at 11.43V which does not seem right.
At this point it does seem the battery is bad, but it tested fine at O'Reilly. Could it test fine but still not hold a charge? Would Walmart accept a return if it passes the load test?
I've disconnected the battery and will watch if it continues losing voltage today/tonight. At least I can rule out whether the battery itself is not holding a charge.
I know you said it was a new alternator, but sometimes stuff is bad out of the box.
Did you do the AC/DC test while the truck was running? If not give it a go, could have a shorted diode in the alternator causing the parasitic draw. That was my problem last summer on my 2001 Excursion.
So if you see AC current, there is some ripple in every alternator but most meters won't catch it, that is say 1 volt or more the alternator has a bad diode that is causing the draw.
No I haven't done a AC/DC test while running. Not exactly sure what that refers to but I will look it up...
I unplugged the battery immediately after driving on Thursday. It was around 12.1V, which seems pretty low for immediately after a 15minute drive. The next day it was about the same, but today it was down to 11.6V. This is keeping the negative terminal unhooked the entire time.
I got a new clamp style ammeter and found today that I am not seeing anything higher than around 0.05A after the GEM went to sleep.
Due to both of these things, I feel the battery itself is probably bad. Going to try to return it at Walmart but not going to get my hopes up that they will see it as "bad." May just have to purchase a new one.
No I haven't done a AC/DC test while running. Not exactly sure what that refers to but I will look it up...
Pretty simple, after you start the vehicle just check the voltage at the battery posts. DC current should be 14.2-14.8V, then set the meter to read AC current. You should not get a reading on AC current, if you do get anything over .5 V a diode is shorted causing the drain.
Could still be your problem as you left the positive connected and it runs straight to the alternator. It wrecked a brand new battery on me before I traced it down to the faulty alternator diode.
Thanks I will try that tomorrow when I run it again.
Yesterday Walmart said it tested good but was low charge. So they let it charge for an hour. At that point, it was closing time. The battery was still charging so they let it sit overnight.
Today, they said it was charged but tested bad. I didn't ask too much and happily took a replacement. Put it in the truck, and it is measuring around 12.8V. I am going to do the AC test tomorrow (I have done the DC test at around 14.6V last week). I will also keep checking for any draws, in case they battery was actually good (or "would have been good") but I drained it too many times.
Pretty simple, after you start the vehicle just check the voltage at the battery posts. DC current should be 14.2-14.8V, then set the meter to read AC current. You should not get a reading on AC current, if you do get anything over .5 V a diode is shorted causing the drain.
Could still be your problem as you left the positive connected and it runs straight to the alternator. It wrecked a brand new battery on me before I traced it down to the faulty alternator diode.
I measured 14.55V this morning but like 34V on the AC volt setting. The smallest scale is 200 on my multimeter. I am just getting a bad reading or is that normal for a shorted diode?
I measured 14.55V this morning but like 34V on the AC volt setting. The smallest scale is 200 on my multimeter. I am just getting a bad reading or is that normal for a shorted diode?
Wow, I had a 5.4V AC on mine causing the draw. Yeah I would say time for a new alternator, that thing is a battery killer. Disconnect the battery right away to save it. When I had that issue it would take 3-4 days of sitting to kill the battery. Yours being that much higher of a reading makes sense on how yours would die overnight/within hours.
Well you know what is causing the problem now, and it is an easy fix. It is called alternator ripple, if you want to look into it, basically you shouldn't see any with most meters (and no more than .5v if you do see it).
No it was the battery. The reading I was getting on the multimeter test is actually normal when you use a cheap multimeter.
I've let it sit out for about a week now due to COVID19 and it started right up the other day.
In fact the new alternator might be worse. I hear a faint whine that is RPM-dependent and my guess is it is the alternator since that's the only thing that has been swapped recently.
I'm surprised a new battery could be bad like that, but that seems to be all it was. I wish I had just swapped the battery out before wasting so much time looking at other things, replacing the alternator, cleaning the GEM, etc...
Damn, that's unfortunate. I have the same situation going on and have always suspected the battery(s). Sounds like I need to focus my troubleshooting on the batteries first and go from there.
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