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Ground in GEM Module??


JPW

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1999
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Ford
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Hi Guys, new to the forum so I appreciate any help I can get.

My battery would die if I didn't drive the truck for 4-5 days, so I decided to check to see if there was any current draw while the truck was not running. I found about 0.23 amps drawing all the time, so I started pulling fuses until I found the problem. The problem fuse was fuse 25, GEM and instrument cluster. I disconnected the GEM and the current leak went away. My question is...

Do you guys have any idea how to troubleshoot from here? I guess there must be a ground on one of the wires connected to the GEM (I think the harness that connects in the top of the GEM), but I'm not sure the best way to check these.

Thanks for your help!

Joe
 


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RonD

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Welcome to TRS :)

1999 Ranger will have a Battery Saver Relay, so .23 current draw would be normal for 20-30 minutes after key is removed and doors are closed.

The GEM runs that relay so it will be drawing power until it "times out" and battery saver relay opens.
Pulling the fuse turns off GEM and opens relay.

Current draw after the 20-30min should then drop to .03-.07
Radio preset/clock, Computer memory, and keyless entry need to stay powered on.

It is possible Battery Saver Relay or GEM are at fault but I would check battery first

Batteries can get internal shorts, so test for that
Unhook battery and put volt meter on it, 12.3-12.8 volts is a good battery
12.8v is new
12.5v 3/4 years old
12.3v 5/6 years old and time to shop for battery sale

12.2v and under is failing battery

With volt meter connected watch the voltage, should stay EXACTLY the same, if it drops even a little battery has internal short and is self draining, check it over about 30min time frame.
It it tests as 12.35v and then tests as anything below 12.35v then it is self draining

There are 6 cells in a battery and each cell has many plates that are very close together, if one plate gets shorted to another plate then battery starts to self drain, no fix for it, unless you rebuild battery cores :)
The plates store and release voltage, as this happens they exchange electrons, this exchange does cause a build up on the plates, if the build up gets too much and plates physically touch then it is a short
 
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JPW

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Joined
May 9, 2018
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2
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Vehicle Year
1999
Make / Model
Ford
Transmission
Automatic
Awesome advice. Okay, I'll try this when I get home today. The battery is new within the last year, but I'll check to make sure it's not defective. Thanks again and I'll keep you posted.
 


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