I have a 99 gt convertible that keeps dying every night. Drain is 0.17A which doesn't seem like a lot but keeps killing the car. Battery is from September 2022 and I tested it and is good. Fuse 6 under the hood for I/P fuse panel, Instrument cluster, Powertrain control module(PCM) seems to be causing a drain. However, fuse 39 under the dash also seems to be causing the same drain. Does anyone know how to fix this drain. It's driving me crazy I don't know what to do.
Battery Drain 1999 gt convertible
- Thread starter atomicfox237
- Start date
-
Sponsors (?)
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.
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 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.
Try the GEM first. That's what Fuse 39 feeds. See if that stops the drain.
View: https://youtu.be/3umZ6h0qD_4
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
View: https://youtu.be/3umZ6h0qD_4
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
Dug around on my car a bit.
0.35 amp draw on fuse 6. Haven’t gone much further but looks like I have the same issue.
0.35 amp draw on fuse 6. Haven’t gone much further but looks like I have the same issue.
0.35 amps drops to 0.16 amps when I unplug the drivers side mach amp. No change on pass amp.
GEM standby is about 120 milliamps, which is .12 amps. It should drop to 35 milliamps after 40 min.
So my next step is to rig my meter up to stay connected for 40 mins until the GeM goes to standby. Should be about 0.035
Amps then.
Radio memory draw will add a tiny bit to that number
GEM standby is about 120 milliamps, which is .12 amps. It should drop to 35 milliamps after 40 min.
So my next step is to rig my meter up to stay connected for 40 mins until the GeM goes to standby. Should be about 0.035
Amps then.
Radio memory draw will add a tiny bit to that number
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.
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.
If the gem goes into standby, pull fuses again. Another common culprit is the alternator voltage regulator.
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.
If the gem goes into standby, pull fuses again. Another common culprit is the alternator voltage regulator.
Last edited:
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.
Yes, the GEM controls pretty much all the interior components that do not have to do with the engine management. So while the fuse points to the GEM, it doesn't necessarily mean the GEM is the culprit. Could be a failing door latch or interior light bulb shorted.
But what's important to note is that the GEM is active for about 40 minutes after you turn the car off. Only then it goes to sleep mode.
Your initial drain is 0.17 amps, which is 170 milliamps. That's about what the GEM draws before it goes into sleep mode. 150-170milliamps is about where i've seen it quoted when it's active. That's why you need to set up your meter in such a way that you can leave it hooked up for 45 mins or so to see if that 0.17 amp draw goes away. If it doesn't, then that points to the GEM remaining active either because it's bad, OR because something it controls keeps waking it up preventing it from going in standby mode. I don't believe it takes much to keep it awake, so the actual draw could be very little but just enough to keep the GEM awake.
That's where I am right now. I unplugged one of my Mach 460 amps and the draw went from 0.35A to 0.16A. So i'm about where you are. I need to rig up my meter tonight to let it sit for 45min and see if it drops down to 0.050A or less.
But what's important to note is that the GEM is active for about 40 minutes after you turn the car off. Only then it goes to sleep mode.
Your initial drain is 0.17 amps, which is 170 milliamps. That's about what the GEM draws before it goes into sleep mode. 150-170milliamps is about where i've seen it quoted when it's active. That's why you need to set up your meter in such a way that you can leave it hooked up for 45 mins or so to see if that 0.17 amp draw goes away. If it doesn't, then that points to the GEM remaining active either because it's bad, OR because something it controls keeps waking it up preventing it from going in standby mode. I don't believe it takes much to keep it awake, so the actual draw could be very little but just enough to keep the GEM awake.
That's where I am right now. I unplugged one of my Mach 460 amps and the draw went from 0.35A to 0.16A. So i'm about where you are. I need to rig up my meter tonight to let it sit for 45min and see if it drops down to 0.050A or less.
Last edited:
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)
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)
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)
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.
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 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?
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.
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.
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?
Edit: I guess my meter just wasn't working because I tested again and it starting to show a reading. So I had all the fuses unplugged and waited the 45 mins. 45 mins went by and still was draining 0.17 amps. Are there any other fuses that could be part of the issue?
Last edited:
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
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
Similar threads
