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I bought my 1997 f150 4.6 Lariat XLT 4x4 new.. Has about 300,000 miles in it..Been a unbelievable truck, with No major issues just maintenance..Just great!.. But I have had issues/problems with the 4x4 engaging/disengaging, sometimes works great other times not,, I rarely use it (truck) much anymore.No one has worked on my truck but me.. BTW....I'm a 67 year old ex electronic engineer..and also a business of restoring classic muscle cars ( special,specifically 70-72 Pontiac GTO's for around 25 years ( own a full shop)..This issue has been going on for a few years..Some times it will work.. but rarely now..If I disconnect battery and short the ends it will "reset" the system ( GEM) I assume and work again.. sometimes not but usually does..LOL All the hardware is operating , only when it feels like it though..After a "reset" usually works.. SOO.. I assume there is a issue with the Gem.. maybe capacitance/transistors other components in the GEM.. are weak? no other issues with the truck, electrical OR mechanical..Don't see ANY water intrusion also.. Anybody else familiar with this? Also to mention, I completely restored the interior ( leather/grey) and my red truck looks almost new! Thanx for any help opinions,,
I'm not positive but I don't think that a 1997 GEM has memory. I think it just responds to inputs. So there's nothing to reset in the GEM. The PCM has memory though.
Might help to give more clues. Is there a light that indicates 4WD? Does it light up and 4WD doesn't happen? Or does it not light up and nothing happens? Usually it's in parallel with the power to the shift motor, as I understand things. Probably help to get a wiring diagram.
Thanx!.From what I responded from a reply on the "other "ford forums....".I'm 69 years old by the way! And yes I also have 2 1970 Pontiac GTO's.and a 2011 VW Jetta tdi.. ( turbo diesel). the older the better! Sooo...I understand it may not have "memory".. But it does have timing devices on it.. in particular capacitors..And the GEM I assume does operate on timing of events...so If I discharge the gem by shorting the bat. cables together ( discharging components, caps in particular on the gem)'' a recharge occurs when reconnecting and temporarily works.. I have NO water intrusion.so I pulled the GEM out of truck and am testing it... But I do have a capacitor (C61 micro flush mount) that does have a "trail" and has discoloration on it also not getting the vom readings I would like to see on this cap....All the components to operate the 4x4 (solenoids, relays, diaphragms, indicators etc..) functions and works properly AFTER a reset..sometime works a few times then fails.. dead! Till a reset is done again....I don't have the "specialized micro soldering tools" any more to do a repair...Just curious if anyone has/had the same symptoms and discovered what the problem was.. I appreciate it!"
Tried to find your capacitor on the old internet but all that comes up is large sizes. No micro.
Any chance you can hardwire a new one in? Clip some legs and crimp in a new one? Just a thought I've had but never tried for computer applications. More room there though.
Maybe it's part of the motor starting circuit and you're on the right track. Not an expert. Good luck.
If the capacitor has leaked, it needs to be replaced. Take a photo and others here can help you find one. Buy a decent soldering iron, desoldering tape and some flux. The repair will cost under $100. If your DVM has a capacitor setting, you can measure capacitance after it is disconnected from the circuit.
Thanx but these are "micro" caps..not the typical 2 legged disc or tubular types (easy to replace)..very special tool are required to remove and replace.. I have very good soldering tools and de soldering tools etc..flux and solder But not the micro that is required.....I have a friend who may help...Problem is without more info ..won't now the specs on this cap. Cap is c-61...go down about halfway .it is just to the right of a dark looking screw is the best picture I could take..but you can see it looks darker than the one next to it..Not to mention ..no reading on my DVM set on caps.. A DVM check shows a open circuit thru the cap..all others have a forward bias..might have to buy another gem..we:ll see! Anyone have a schematic on this GEM board which will show the capacitance of this!? Thanx again
Last edited by FORREST2; Mar 12, 2026 at 02:53 PM.
This is not an electrolytic capacitor that are famous for leaking. But it could be bad. Looks like heat from the component on the other side of the PCB may be the cause...but I don't know. Since the marking on the cap is gone we have no idea what size it is without a circuit diagram.
A junkyard GEM may be the best option. It will show you the cap marking (if needed) and may fix the problem without going down a rabbit hole. But I don't know that the GEM is the cause so proceed on your own diagnosis.
Last edited by Don Ridley; Mar 12, 2026 at 02:51 PM.
I see it. Are you sure that's not simple soldering iron work? There's just a pad on each end. Not sure that's micro level. Just surface mount. I've been watching several repair channel videos. They do some amazing small work. They'd do that with a soldering iron.
Is it no reading because it's open, or no reading because it's shorted? Or because you're on the capacitor setting. Have you measured resistance to check? Just curious.
Hey bones and Don.... I could try to remove it with what I have.. BUT micro soldering uses a very small needle type tip with specific temps to avoid damage to the components,traces etc,,The cap is OPEN .. NOT shorted..all other similar caps show continuity only one way and none reversed..With caps check mode on the VOM,, all others show a forward bias only one way.. My bad one shows none. And Don none of the other micro caps have any specs on them either. I hope you understand? And thanks! schematic anyone??
Last edited by FORREST2; Mar 12, 2026 at 03:24 PM.
Hard to see why a power "reset" would bypass an open capacitor circuit problem. Seems like there must be more going on.
There's a bunch on eBay. A sign that there's an active market for them. Apparently (not positive), they are plug-and-play if you get the right part number. Looks like a fun problem. Have fun.
You have PIDS to check in GEM for 4x4 operation and diagnosis and testing
Just about NO scan tool short of a Ford NGS will talk to the gem to check those pids
Grab a 1997 service manual and find one of these
