The wife called me from work last night and said there was a ghost in her 99 Expy and it won't start. So I headed on down with some jumper cables to give her a jump and get her home. When i arrived the radio was on and the heater/AC fan was turning on and off with a buzzing going on under the hood. I opened up the relay bow and identified the wiper relay chattering. Swapped it with another and it still chattered so i removed it. I went to try and start her up and it cranked fine but wouldn't start. Checked the fuel rail and had fuel so figured probably no spark. Even with the key removed the dash acted weird with various indicators turning on and off, 4x4, check susp. service engine soon and the HVAC fan running. Out of desperation I removed the negative battery cable for about a minute and reconnected it and it started right up to drive home. Now she mentioned that similar things would happen when she would go through the car wash occassionaly, and it did rain hard yesterday. This was the first time it didn't start. I'm guessing water is getting in somewhere to something, just not sure where to start. I'm an old IDI diesel guy, no computers in my rig. Has anything like this happened to anyone here?

Thanks for any help in advance. Where would the GEM on a 99 EXPY be located? I'm not even sure how to get the dash apart but i think that's the direction I'm headed... unless someone has been down this road before.. Maybe I need garlic...

paul

 

The leaky winsdshield problem is very well documented and has frequently caused the GEM to malfunction. If you can do a forum seach, you will find a lot of threads.

 

Scott's given you the most likely cause.

 

I had my GEM module replaced and my windshield re-sealed at the dealership to the tune of $860.00. It was raining one afternoon after work, got in and she would not crank. Jumped her off. When I pulled it down into gear, radio, wipers, lights all went NUTS! This somehow caused my starter to fry, too.

 

Has anyone replaced the GEM themselves? On my 99 Expy it looks like it might be behind the drivers side fuse panel, but I'm not sure. I can feel a black box there. The next question is how to get to it... I have dried everything out some what and everything seems to be acting normal, for the time being. I wanted to get the GEM out and clean the plug contacts, maybe coat with WD-40 and use some dielectric grease on re-assembly then check for corrosion behind the fuse block.

Has anyone replaced their GEM unit themselves? Does a 99 need to be programed or just R&R? Of course the windshield will have to be re-sealed. Thanks again for any input.

 

It's pretty simple.. on the left side behind the dashboard.. a black box (some may be white).. maybe.. i dunno... 6" by 8" by 2"? And as far as I know does NOT need to be reprogrammed.

Once you have it out you can remove the plastic "shell" and get a good look at the circuit board.. look for signs of moisture.

Good luck!