Thank you for the reply. However, I do not have the Mach sound system in my mustang. Do you know where I should start in terms of that? I keep hearing about the Mach sound system but I can’t seem to find any info on cars that weren’t optioned with them.Fuse #6 and #39 is a common source for the power drain on these cars.
When operating normally, remove fuse F6. Put your meter in place of that fuse and set on Milliamps DC. When you close the doors with the car off the meter will read over 200mA (I have an LED dome lamp - yours may vary) until the dome light shuts off. Then the meter will read about 112mA for about 40 minutes. After that the PCM goes into standby and the meter will read about 12mA steady state.
Anything else, and you have something causing a parasitic draw on the battery. Most common source tends to be the Mach 460 amps. They are supposed to go into standby mode but as they age the internal compoents fail and should be replaced (caps). Try unplugging the amps and see if that solves it.
Some reference wiring diagrams here
Fuse #6 also feeds
1 20 amp--------Lighter
7 15 amp--------Main light switch, Generic Electronic module
13 15 amp--------Electronic flasher
19 15 amp--------Park lamp relay,Exterior rear view mirror switch, Master window/door lock control switch, Right window/door lock
25 25 amp--------Luggage compartment light
31 10 amp--------Data Link
I'm going through a similar drain on an '00GT but haven't gotten that far in testing yet. Mach amps are so common that's going to be the first thing I unplug.
Thank you for this. Do you know what systems each plug controls on the GEM? I was thinking about disconnecting one at a time to see if I could narrow my searches to a specific system. Or maybe even see if I should change the whole module itself.Try the GEM first. That's what Fuse 39 feeds. See if that stops the drain.
Be careful with it as the GEM is sensitive to impacts.
Give this a read. The GEM is active for up to 40 mins after you turn the car off. But the draw should be much less than 0.17 amps. That's a big draw
GEM MODULE DRAWING POWER WHEN VEHICLE IS OFF!!! - MustangForums.com
4.6L (1996-2004 Modular) Mustang - GEM MODULE DRAWING POWER WHEN VEHICLE IS OFF!!! - today i found out what has been draining my battery. today i pulled the fuse inside the car and it was the GEM module fuse. does anyone know how to fix this problem? something is pulling about a quarter of an...mustangforums.com
Thank you. Maybe I am not understanding post #2 correctly, but are those what the GEM module itself controls? I was thinking about disconnecting each harness from the GEM itself and seeing which plug stops the drain. And from there see what that plug specifically controls.The systems are listed in post #2.
I’m literally troubleshooting this same draw as we speak. It’s a common issue.
This thread might be worth a read
Really need to set up your meter and walk away for 45 min and see if current draw drops. Should be under 50 milliamps then. If you are testing while opening doors or making the car active, the GEM wakes up.
Need to open a door, flip the latch so the door things it’s closed and set up the meter by taping the leads to the batter and terminal and go have a coffee. After 45 mins if you still have 160milliamps or more, the GEM may not be going into standby.
Im definitely going to try this today. However, how did you figure out the radio was part of the draw? I have an aftermarket radio but I'm not sure how to check if it's the cause.As suspected. GEM just needed time to go to standby.
In my case, the source of the draw was the radio/amp. Both my head unit and one rear amp was bad.
0.16 amps when I start.
After about 35-40 min, the GeM goes to standby and draw is 0.019 amps (19 milliamps)
I just tested this for an hour. Had both sides of the meter taped to the battery terminal and the car and it didn't change from 0.17A. I didn't have the doors locked though if that makes a different. What would be the best next course of action?It’s just so common it’s where I started. First thing I did was unplug the head unit and amps.
0.16a seems to be typical when the GEM is active. Need to give it 40 mins to see if it goes to sleep. If it doesn’t, then you have a problem.
I just tried this. I unplugged the battery, then unplugged the 6 fuses from post #2. However, I went and checked the drain right after the fuses were disconnected and the meter read 0. I could not get any reading. I don't know if this is a good thing or bad thing. Isn't there supposed to be some sort of drain?Pull all the fuses in post #2. Repeat seeing if the GeM will go to sleep.
Lock the pass door, open the drivers door and use a screwdriver to flip the latch to closed. Then go have a beer for 45 min with your meter connexted. See if it goes to sleep then.
If it does, something on those circuits is keeping the gem awake. Put back one fuse at a time and see if anything wakes the gem back up.
Going to try and revive this thread here, as I’ve tried to follow this post to the letter and cannot confirm if I am doing this correctly. On my 1999 GT Convertible with Mach 460 amps, I get a dead battery every few days. First I disconnected the negative battery terminal and hooked my meter (mA DC) between the battery post and the terminal. Initial reading is ~0.76mA. Doors closed and locked, roof down. Disconnected both rear amps, no change. Removed the 40A Maxi (No. 6 under the hood, as No. 6 under the dash is for the starter relay according to my owners manual), no change. Currently waiting for the 40minute timer to go off, but these numbers aren’t close to what the rest of the thread is saying is the general readings for the GEM (before or after going to sleep). Am I missing something? New to this so trying to learn, any help is appreciated!These are all the things that tie into the GEM.
You’ll just need to go down the list and unplug various items and see if the GEM goes to sleep. Sounds like it’s not
Sorry I don’t have more info. I haven’t gone that far myself with this
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