You will need to check it for a draw using the DA amp feature. Set it on the 10 amp scale and unhook the neg. cable then hook a jumper wire with alligator clips in between the neg cable and the battery neg post. This is to keep from blowing the fuse in your meter until the computer goes to sleep. Here is how you will hook it up.
Before you begin open the drivers door and then take a screw driver and trip the latch on the door so the interior lights will go out. This way you can get to the fuses to unhook them. After hooking up your meter wait about 30 to 45 minutes so the computers will go into the sleep mode. Then unhook the jumper wire so all the amps are going thru your meter and take a reading. You are looking for 0.05 amps(50 milliamps) or less,anything more is excessive. If you have more than 0.05 amps then start unhooking fuses one at a time. Start in the under hood fuse panel first. Now you have to be patient while doing this,sometimes when you unhook a fuse your reading may jump up but should go back down in a couple of minutes unless you activate something like a interior light.
The reason I state to start in the under hood fuse panel is because all of the interior fuse panel fuses are fed by the under hood fuse panel so this will help you to narrow it down to which fuses to unhook in the under dash fuse panel to try and localize the circuit causing the draw.
DO you have an owners manual so you can see what the fuses feed?
Well thats good to hear that you are an electronic technician. Makes it alot easier when posting information for you, I don't have to try and explain every step.
Here are the wiring schematics for the systems you are needing.
Now the main thing you need to concentrate on is the GEM module it is tied into both of the items you have here .It is located right under the radio and you may be right on about a wiring concern.
Here are the schematics for the GEM
Here are the schematics for the radios
Here is what fuse 26 feeds
Here are the instuctions to remove radio and GEM module
Remove the radio chassis
Now one thing I need to point out to you is the GEM is a module or computer operating on a windows based operating system. So think of it like your home computer, is something keeping it from going to sleep or screen saver like something activating, like moving the mouse so to speak. Look at all the inputs if you do not find nothing at the radio.
If you need pics of the connectors at the radio let me know and let me know which radio it is that you have.
I would say the radio is a definite problem but the GEM may or may not be. After you unplugged the radio and the amps dropped from 700ma to 200ma did you wait another 30 minutes to see if the GEM would go to sleep? The reason I asked is that maybe the radio is keeping it awake. Now if you wait the 30 minutes after you unplugged the radio and you still have the 200ma draw then you definitely have another problem. Now it would be premature to jump on the GEM module because it could still be receiving a signal from something that is keeping it activated. Think of it like your home computer and you keep wiggling the mouse or touching a key on the key board to keep it from going into screen saver.
Here are the schematics for the GEM module so you can see what all it hooks to,remember it is a computer. It is not that hard to replace it but it has to be programmed so this would have to be done by the dealer or by someone with a scan tool that is capable of doing this.
Glad to hear you have your problem solved.
Thats the reason you have to be patient and so careful when you are working on these things.Imagine trying to do this on like a Lincoln MKS that has about 20 computers on it.
Yes I have experience 1st hand.
I have a 93 model 2.3L 5 spd that has 180K miles and still runs strong.It has been thru 2 teenage sons and the only thing besides maintenance has been an alternator, clutch,and a heater core.
It is affectionately referred to as the danger ranger by my two boys.