Howdy Fellas. I have a '99 Expy XLT with a 5.4 4x4 that has been having electrical problems for some time. Recently they have come to a head and I am looking for some guidance. I'm trying to tell if this is one of the "GEM" problems. I've had wacky front wipers that have had a mind of their own for years. My overdrive button only functions when the shifter is in park. Most recently, my interior lights come on when they feel like it when the truck is off and all doors are closed. I've tried cleaning the door and lift gate latches with WD-40 with no success. Also, when the lights come on the door ajar light does not come on. I've replaced the battery, 3 months ago, and the alternator 2 weeks ago. I've also replaced the interor lamp relay #1 and that has not solved the problem. My windshield has been replaced a few times due to cracks and I assume that it does not currently leak. I have replaced the turn signal/windshield wiper switch/lever with no success. I have tried replacing the overdrive switch without success also. Can any of you fine folks tell me if this sounds like the GEM problems that have plagued our trucks or if it is something different entirely. I am at a complete loss and dreading the one or more trips to the dealer to get this fixed... Thanks in advance!!

Smitty

 

Sounds like it. But removing the fuse box and GEM and looking for signs of corrosion is a better way to tell.

 

I was convinced that I had GEM problems. I took my Exp. to a local Auto Electric shop to have it checked before I invested big bucks in a new one. Discussed it with the technicians agreed that it sounded like the GEM.
When they called me with the results of the testing..... It was one of the license plate lights that was shorted out. He cut the wires, taped them up & I haven't had ANY problems since.
I found out years ago that it is usually cheaper for *ME* to have someone else check any electrical problems then try to figure them out for myself.

 

Thanks for the replys gentlemen. I've had an issue in the past with my license plate light where it shorted out, blew and popped a fuse. I replaced the light recepticle and the fuse. I think tonight I'm going to pull my fuse panel and GEM to see if there is any evidence of corrosion and go from there. I'll keep you fine folks updated...

Smitty.

 

good luck and please do keep us posted.

 

I also have a 99 XLT and had some of the same issues. The wiper- i believe that there was a recall/TSB on the 'multi function' turn signal related to the wipers just going on for no reason. They replaced ours under recall (or somereason for free)and that fixed that. The Overdrive- their are 2 very thin wires which run down the gear lever and turn down the steering column. It's also very common for those wires to break inside the sheathing. Seeing you say that the only time it works is when it's in Park could be a good indication seeing maybe the wires in are in a 'connected' position when in Park, but anything else 'stretches' the wires and then doesn't work. Those wires are an easy diy fix. Not saying these are your problems, but these were mine w/ the fixes.

 

Alright folks, I apologize for the delay in my response. Here's the deal. So after attempting to look at the GEM and find the cause of the problem that way, I broke down (not literally) and took my truck to the stealership. The cause of the dome lights cycling on and off was a stuck key on the keyless entry pad on the drivers door. Replaced and problem solved. The OD button only working in the Park position was due to the sheathing being worn away on the wires inside the shifter and they would ground out in any other position. I beleive user '680276122' called that one. Replaced the whole shifter and problem solved. Oddly enough my wipers have been fine ever since I replace my alternator, so perhaps it was an under-volt problem or something. So those issues were fixed at the dealer and with an oil and filter change and an inspection sticker total was $551.47. Not too bad. Just $0.34 more than a payment on my loan, but seeing as I had mailed my last payment on the vehicle a few days earlier , I think my truck was just trying to get one more out of me...

Anywho, have a great day gents and ladies.

Smitty