2000 Excursion 7.3L battery drain
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Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
2000 Excursion 7.3L battery drain
If I leave my truck sit for a couple of days, the batteries are noticeably weaker. It's fine overnight, but two nights and it's slow to crank. Three and it won't start without charging the batteries. I checked for a drain last night and found that it was drawing 1.2 amps.
That seems like a lot, no?
That seems like a lot, no?
Post Fiend
Joined: Mar 2015
Posts: 5,277
Likes: 32
From: Blairsville, Pennsylvania
I chased a similar trouble some time ago and found I had a bad starter/solenoid.
I was using a plugin ammeter in the fuse block, but nothing stood out.
Then the starter wouldn't crank one day. Aha! Found it, LOL.
Hopefully it is that simple for you
I was using a plugin ammeter in the fuse block, but nothing stood out.
Then the starter wouldn't crank one day. Aha! Found it, LOL.
Hopefully it is that simple for you
Thread Starter
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Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
I pulled the wires off the alternator and it was still there.
I went through the fuse box and pulled a fuse, checked the current, etc. and found two fuses that made a significant difference: 14 and 15.
Removing 14 takes about an amp of the draw away, but with 15 still in, it's still drawing 200mA. After pulling that one, it drops to almost zero.
According to the manual, 14 is the dome lamp, cargo lamp, courtesy lamps, running boards, power mirrors, vanity mirrors, map lamps, underhood lamps, and glove box lamp.
15 is the stop lamp switch (logic), PATS, and GEM.
What now?
I went through the fuse box and pulled a fuse, checked the current, etc. and found two fuses that made a significant difference: 14 and 15.
Removing 14 takes about an amp of the draw away, but with 15 still in, it's still drawing 200mA. After pulling that one, it drops to almost zero.
According to the manual, 14 is the dome lamp, cargo lamp, courtesy lamps, running boards, power mirrors, vanity mirrors, map lamps, underhood lamps, and glove box lamp.
15 is the stop lamp switch (logic), PATS, and GEM.
What now?
Post Fiend
Joined: Mar 2015
Posts: 5,277
Likes: 32
From: Blairsville, Pennsylvania
I pulled the wires off the alternator and it was still there.
I went through the fuse box and pulled a fuse, checked the current, etc. and found two fuses that made a significant difference: 14 and 15.
Removing 14 takes about an amp of the draw away, but with 15 still in, it's still drawing 200mA. After pulling that one, it drops to almost zero.
According to the manual, 14 is the dome lamp, cargo lamp, courtesy lamps, running boards, power mirrors, vanity mirrors, map lamps, underhood lamps, and glove box lamp.
15 is the stop lamp switch (logic), PATS, and GEM.
What now?
I went through the fuse box and pulled a fuse, checked the current, etc. and found two fuses that made a significant difference: 14 and 15.
Removing 14 takes about an amp of the draw away, but with 15 still in, it's still drawing 200mA. After pulling that one, it drops to almost zero.
According to the manual, 14 is the dome lamp, cargo lamp, courtesy lamps, running boards, power mirrors, vanity mirrors, map lamps, underhood lamps, and glove box lamp.
15 is the stop lamp switch (logic), PATS, and GEM.
What now?
But seriously, make sure you have the door closed when checking
Thread Starter
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Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
All doors were closed. The only light on was the underhood light. That light can't draw an amp, can it?
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Laughing Gas
Joined: Nov 2013
Posts: 868
Likes: 1
From: SoCal
I had the same issue and it was because I had too much crap in my glovebox. It would close, but the light stayed on.
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Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Sure, why not... an 1157 (tail light bulb) draws 2.1 amps. I don't know what # they use under the hood but anything that would provide useful light would have to draw at least a little bit of juice.
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Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
OK I think it was the bulb. But I got some odd results and I don't really know what they mean.
With the bulb removed, and one battery hooked up, the current draw fluctuated around 350 mA. Still too high. I pulled fuse #14, and the draw dropped to 190 mA. I replaced fuse #14, and pulled fuse #15 instead, and the draw dropped to to 14.9 mA. When I pulled fuse #14 back out, it remained at 14.9 mA.
So:
Both #14 and #15 in: 350 mA
Pull #14: 190 mA (suggesting a ~160 mA draw on #14)
Replace #14, pull #15: 14.9 mA
Both fuses pulled: 14.9 mA
I checked these numbers twice. Does this make sense to anyone? I know this is a little hard to follow, but if two circuits pull a combined 350 mA, and removing one circuit draws 190 mA, doesn't that mean the other circuit has to be drawing about 150mA?
And yes... I noticed that the draw takes a few moments to stabilize.
I did this with one battery hooked up. I disconnected the battery, connected the other one, and repeated the tests. Same results.
With the bulb removed, and one battery hooked up, the current draw fluctuated around 350 mA. Still too high. I pulled fuse #14, and the draw dropped to 190 mA. I replaced fuse #14, and pulled fuse #15 instead, and the draw dropped to to 14.9 mA. When I pulled fuse #14 back out, it remained at 14.9 mA.
So:
Both #14 and #15 in: 350 mA
Pull #14: 190 mA (suggesting a ~160 mA draw on #14)
Replace #14, pull #15: 14.9 mA
Both fuses pulled: 14.9 mA
I checked these numbers twice. Does this make sense to anyone? I know this is a little hard to follow, but if two circuits pull a combined 350 mA, and removing one circuit draws 190 mA, doesn't that mean the other circuit has to be drawing about 150mA?
And yes... I noticed that the draw takes a few moments to stabilize.
I did this with one battery hooked up. I disconnected the battery, connected the other one, and repeated the tests. Same results.
Thread Starter
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Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
I think I figured this one out. I looked at what's on fuse #15, the stop light logic (whatever that is), the GEM module, and the PATS module. "What's a GEM module?" I asked myself... and did some reading. This thing apparently controls a lot of different electrical systems, including the radio, the windows, and if it were malfunctioning could certainly explain the strange observations I made yesterday with the multimeter.
So I'm trying to remove this thing and see if the connectors are corroded and I found a couple of old threads:
https://www.ford-trucks.com/forums/9...e-removal.html
https://www.ford-trucks.com/forums/8...odule-gem.html
which give pretty good instructions for removing it. I followed them but they don't seem to make mention of the large loom of wires coming down to the fusebox panel from the upper dash.
I can't get it twisted around to where I can remove the GEM module, and I don't see how the loom comes off the panel (and the instructions don't mention anything about it) so the panel can come out far enough.
So I'm trying to remove this thing and see if the connectors are corroded and I found a couple of old threads:
https://www.ford-trucks.com/forums/9...e-removal.html
https://www.ford-trucks.com/forums/8...odule-gem.html
which give pretty good instructions for removing it. I followed them but they don't seem to make mention of the large loom of wires coming down to the fusebox panel from the upper dash.
I can't get it twisted around to where I can remove the GEM module, and I don't see how the loom comes off the panel (and the instructions don't mention anything about it) so the panel can come out far enough.
More Turbo
Joined: May 2016
Posts: 717
Likes: 9
You need to allow the GEM to enter Sleep Mode for an accurate measurement. Some stay on as long as 10 minutes. Leave the door open until the Dome Lamp goes out..... It's sleeping.