No "BCM" (I think of that as being a Chrysler Term). But now for the confusing part

During the '01 run, some got a GEM, some got a VSM (the electrics were being updated) and how you can tell is actually by the Instrument Cluster (which itself became a Module, taking the GEM's basic functions). IF your cluster has a Digital OD and a Trans Temp Gauge in it, then you Do NOT have a GEM. IF you don't have those things in the cluster then you HAVE A GEM (located on the backside of the in-cab fuse panel and the first thing you should look for is that it's been getting Wet because of a, common, windshield leak)

Whether or not you have a VSM (Vehicle Security Module) depends on the trim level of your truck. Trucks with only the basics (no central locking, no ESOF, that kind of stuff) had no need of the VSM as the Cluster was doing the basic body functions now.

 

THAT IS confusing for sure. i do not have any stock digital guages in my cluster, and definetely no transmission temp gauge.

i do have the esof though. when i switch it to 4x4 low, the "low" light doesnot come on anymore, but the "4x4" is still lit, which i assume means that it is still in 4x4 high. it just i hope the pics come thru. it is an XLT trim. not sure what central locking is

 

well, can't upload my pics

 

Sorry if I wasn't clear in my cluster description Not a digital gauge of any sort but rather the mere presents of a Trans Temp gauge at all (no 2000 has a TT gauge in the cluster and All 2002's do have them). So 2001's have either the "old" (2000 and down) electrics or the "new" (2002 and up) electrics.

But, and maybe even easier, is your Odometer. Does it have numbers on wheels that mechanically turn or digital numbers? (old electrics mechanical ~ new digital).

Again, the 2000 (and some '01's) have no gauge and Mechanical OD) and all 2002's (and some '01's) have a TT gauge and a Digital OD).

Which do you have?

 

i must have the older style with "old electrics" since i do not have a TT guage and my odometer is mechanical. would this indicate a body control module rather than a gem?

 

No, again, the GEM is what Ford calls their BCM and you DO HAVE a GEM (backside of in-cab fusebox) and next you might drop that box (easy to do just 4 screws and it drops down) and look at the GEM for signs of corrosion because it's been getting wet.

You have no BCM, VSM, nor a Cluster that's performing body functions in your '01.

 

got it. i found it behind the fuse box. there are forum posts about pulling a fuse or disconnecting batteries to "reset" the gem ,,,or possible the ecu. do these strategies make any sense,, or just internet myth?

found a place in florida that sells rebuilt gems for 450$ good or bad price? can they even be found new anymore?

 

Lets see what Mike at Autonation has to say about price and availability has to say. @fordsvtparts

 

First step is to disconnect the batteries. Let sit for 15min and turn the key to "run" to drain any residual capacitors. Be aware your trans may shift hard and truck have minimal power for a few miles after reconnecting the batteries - the truck computers are "relearning". This is normal and goes away on it's own shortly.

I doubt this will solve your problem, but why not try the free solutions first?

Next step is to inspect your GEM and fuse box. Remove the bolts and connectors to completely remove both modules from the truck. Look at the large fuse box connectors for signs of corrosion. For the GEM, remove the casing and inspect the board for signs of corrosion or burns. If you see signs of water, replace both and have your windshield resealed. I had a good amount of rust under the window edge so make sure the tech takes the time to grind it and seal the hell out of it. If you don't see obvious damage, I'd look elsewhere before replacing those parts. I've never heard of one fail without water damage, and that usually causes much more widespread issues.

Replacements can be found on eBay for about $100 each. There's 5 or so different versions - a couple are interchangeable but it's easier just to find an exact match. Search the code found on a sticker on the GEM/fuse box itself - it looks like "F81B-14B205-AD" where the last 2 letters differentiate the models.

All that said, sounds more like the problem lies elsewhere. Loss of vacuum is a common problem and causes the original symptoms you describe. Either the hub seals, yellow o ring, vacuum lines, or vacuum reservoir fail and don't allow the hubs to automatically lock. The dash will indicate you're in 4x4 (high or low) but the wheels fail to turn until engaged manually. Shifting into 4x4 low must be done in neutral and you may have to drive a few feet to get the actuator to engage. The light will blink on the dash until this happens. If there is no light, could the bulb have burned out?

 

hi dan, thanks for the post. when you say "re-learning" what i am running a php tuner set up. i have 2 setting i always use, one for normal driving and one for towing. does the truck still relearn if that is plugged in?

 

thanks for help everyone, i think i have problem solved,,,,operator error and early onset alzheimers may have played a factor.