It's a 99 expedition 4x4, 5.4 engine with 158,000 miles. 3 weeks ago we had a new timing chain kit and heater control valve installed. Also a motor mount was missing the 2 bolts that hold the engine to the mount. That we towed our trailer and it ran much better because of the new chain. They said to install the new heater core they had to remove the dash. needless to say the repair bill was enormous. One week later the new battery was completely dead. I charged it at home and it reluctantly started, but all the gauges on the dash were bouncing back and forth. There was a loud clicking sound coming from the left side of the dash near the light switch. This engine was running at this time. I turned it off and the next day attempted to restart it but the battery was completely dead again. It now has been in the shop for a week, trying to track down what is draining the battery. yesterday the mechanic said he thought it might be the "generic control module". He said the part was like 500.00, and it controls all the functions like the lights and such. He ran down a used one but has not installed it yet. i looked at the autozone website and they listed a control module for like 289.oo. Whe used part he showed me was a plastic box with a circuit board inside. It was about 8 inches long and 4 inches wide. Do you think this part could be causing a drain, I think removing the dash may have caused a problem.. Any ideas you guys have would be appreciated. Thanks Bob

 

Do a search here for the GEM because that's the module he's referring to. There are lot's a GEM issues because of windshields leaking. The one quoted at Autozone was probably the engine computer.

 

Thanks , what is GEM?

 

GEM is short for Generic Electronic Module. The module is attached to back of the under dash fuse box. Most of the electrics in the vehicle run into and are controlled by this module, so when it acts up all sorts of weird things can start happening.

 

i am currently having a similiar problem, only not as serious as yours. It rained here pretty heavy most of last week, my 98 sat in driveway. Yesterday i went to get something out of it and realized battery was dead. charged battery and now i get a clicking sound and interior lights flickering whenever doors are closed. This is what i think drained my the battery. The clicking sound was caused by the top left relay in the fuse box. I pulled it today and tried replacing it, hoping it was just a stuck relay but no change. It seems like this relay only controls the interior lights, as everything else seems to work without it. I will leave it out for a few days to (hopefully) let my GEM and fusebox dry out. Then i guess i will try to get the windshield resealed if all goes back to normal when i put the relay back in.

If you do end up spending $500 on a new GEM, I'd be sure to get the windsheild resealed to help prevent it from happening again

 

When mine went out, the blower stayed on when the key was off and ran the battery down.
My extended warranty took care of it, but I was down almost a week because of flooding on I-5, and parts could not get here from Portland, lol.

 

It is the GEM. They found a used one. Any info you have on sealing the windshield would be appreciated. It rained here for like 3 days also when this happened.

 

Just bring it to an automotive glass shop. The windshield has to come out and be re-set properly.

 

And unfortunately, they cannot guarantee the glass will come out without breaking.

I have had to have two vehicles windshields resealed in the last 20 years. Batting .500 so far, lol

 

Of course if you're lucky (cough, cough) like I was with my Expedition to have an object smash into your windshield directly in front of the driver's view; then your insurance company (that likes to overcharge you) will be kind enough to replace the entire windshield. This will solve the leaking issue.