First off this is my first post. This truck was my grandfathers he bought new and hasn’t been driven in years. I have it now and It now runs and drives great thanks to this site but still quite a few issues. This site has saved me so much trouble the past few weeks. I found the common vac leak at the Intake. Recharged the AC and now have pretty cold air. Found the misfire due to a bad ignition coil and changed plugs and coils. Cleaned the EGR ports too. I now have zero codes from about 6-8 a week ago!!!

Now to the next issue. First it’s 1998 F150 Lariat 4x4 5.4. I know the ignition switch has been replaced as the key is different from the doors. I can see the metal under the dash has some rust on it so I’m guessing it could’ve had the windshield leak at one point and been fixed bc it doesn’t leak now. With the ignition in the off position and key out the windows, wipers, and radio all continue to work and will drain the battery in a few days if I don’t remove the #15 fuse And this stops all of that and the drain. This will happen with doors open or closed with key out of the vehicle. The 4x4 doesn’t engage. No 4x4 light but I hear a click under the dash. I have vacuum at both solenoids but it doesn’t change flow when the switch is turned. I have not checked them further so I know this could be a separate issue. Also I know the truck at one time had keyless entry as I have the original window sticker and it says so but can’t get it to enter the programming by turning key on/off 5-8x. I’ve done it on other F150 so I know how it works. I don’t know if the 4x4 and keyless issues re connected to the GEM issue but the radio, wipers and windows causing the drain are all related and can be stopped by removing the GEM fuse which is #15. I believe i could have a bad GEM due to a leak at sometime and I also know the gem controls the 4x4 to the solenoids. If I’m wrong or on the wrong track I’m just looking for guidance and I’ve found plenty of GEMs to buy and switch out to see if that fixes these issues. Just don’t want to buy a $150-200 GEM if It’s not the issue. I’m planning on buying a working GEM if that’s what needs to be done and looking for input on the 4x4 and keyless entry issues before I tackle recovering seats, replacing parts of the cracked dash and fixing the 3rd door bc it won’t open with the handle.

This was my grandfather’s truck so I’d like to get it running right and get all issues fixed so any help is greatly appreciated. I’ll be asking for more help on other issues but these are the ones I’m tackling now as I actually can drive the truck with out fear of it breaking down and it runs and idles great now.

 

It sounds like you're on the right track in suspecting the GEM module. Just be aware that, historically, the leaky windshield can also damage the fusebox so you might end up having to replace both.

Good luck with your grandpa's truck!

 

This may be how to repair the 3rd door cheap and better than buying Ford's new cable latch with the plastic end. You can buy the aluminum cable ends on ebay for cheap.

https://www.youtube.com/watch?v=HGcJ...ature=youtu.be

 

Thanks for the info!!! It’s great how helpful this site is. I haven’t really looked into the 3rd door issue but I’m guessing that could be the answer to my broken door. I’m enjoying working on the truck as well. I haven’t done much mechanical work on vehicles in probably 10 years. My other vehicles are new and under warranty, not to mention so much more complex than this truck. In about a week it’s gone from not even being able to idle without feathering the gas and horrible shaking and surging to honestly running like it’s a few years old. It will be great to use during winter and as a hunting truck. Because I have no intention of ever getting rid of it I’m just going to keep fixing a few issues at a time and hopefully in several months I’ll have it not only running well but looking great as well. I think I’ll even get it painted once everything gets sorted.

I think I’m going to go ahead and order a GEM module in a week or so as no one has suggested that it might be anything else. I can also resell on eBay if it’s not the issue. I guess since I’m doing the GEM I will go ahead and order a dash for it since the dash is cracked. I don’t need the whole dash the piece that is on top of the instrument cluster and kinda wraps around the radio and I need a radio bezel. I know I have to tear into the dash to replace the GEM so might as well do them together.

The great thing about working on this truck is none of the parts are super expensive so far except when I priced new leather for the front seats and that looks like it’s going to be $500-600 for original leather but it will have to be done at somepoint.

if anyone has any tips about the GEM I’m all ears. If I buy a GEM that’s like the one I’m removing do I have to have it programmed or is it plug and play? I’ve read lots of posts about it on here and can’t seem to find a clear answer. That’s really the only concern I have so far.

 

The 97 - 03 F150s may be the most reliable trucks Ford ever produced. The 97 and 98 V6s had an intake gasket issue that could cause problems but the V8s are super with the one minor issue of the plugs blowing out if not torqued properly. Google Million Mile van sometimes and read about the 97 E250 with a 5.4 engine that went over a million miles before finally giving up.

 

I agree. Personally I’ve found the 5.4 from ford and the 5.3 and 5.7 from GM from the late 90s early 2000s to be about the best and most robust engines put in trucks. I’m not total brand loyalty kind of guy just prefer the US brands. My dad does have a Titan with the Cummins and I will say it’s a pretty impressive truck if you can get over the looks. I have had GMCs, Chevys, Fords, and Dodge/Rams. They all have their good and bad. I currently have a 16 GMC 1500 Denali and debating on the next. I like the Ram interior and that huge touch screen is awesome and the ride of the Ram is like a cloud. But my top two choices are a new F150 King Ranch or a new GMC Denali or AT4. I love the look of both of those. I will say that the Silverado could be the ugliest truck ever made. Other than the sky high prices for trucks now it’s a great market with tons of great models

still there is something I just love about this old Ford and I’m not talking about the sentimental value either. I just genuinely enjoy it. A buddy has a 98 Silverado Z71 with under 100k. Flawless everything. The leather and paint looks brand new. He turned down $27k for it not to long ago because you wouldn’t find another like it. Sorry to get off track now back to GEM modules.... 😂

 

This sounds more like a fuse box issue than a GEM issue; HOWEVER, the fuse box and GEM are attached so the leaking windshield could have affected both. I would recommend removing the fuse box and checking it out. You will probably find it has a lot of corrosion on it. If you can, get a used one in good condition from a junkyard, swap it out, and see how many of the issues it fixes. You may still have to replace the GEM, but you may not.