tbone75

First off this is a great site, I've used it alot before posting this. I'll describe problem and list some testing I've done.

I have a 2002 4.6L Lariat ESOF.
The 4x4 light is on but it is not engaged. Moving the selector switch has no effect.
With the key in on position there is no sound of relays or TC engagement under the truck. perfectly quiet.
Tested selector switch and showed proper OHM levels on pins 2 and 3. 3.8k 2wd 1.06k 4hi
Both Solenoids on firewall have suction on lower hoses with engine running

Key on:
Both solenoids show aprox 70 ohms accross pins.
using test light both solenoids have 12V.
BOTH solenoids FAIL ground switch test with dash selector switch in all positions.

so something is preventing GEM from sending ground switch signal to open solenoid and nothing from transfer case
hoping its a fuse or relay? I get no other dash alarms and everything else on truck works properly.

what fuses and relays should I check?

hopefully don't need to replace GEM or dig out Shift relay module under dash.

Thanks in advance for any help!

also this video was helpful in running most of these tests.

tbone75

Also tested fuses 111, 104, 23,20 and 6. all good
Since its 16 years old I'm thinking about wiring around the GEM to engage TC motor. As little as I use 4x4 doesn't make sense to spend alot or tear out dash.

mbb

I'd say fix it properly. When something doesn't work anymore it's detracted from the value of the vehicle. You can realize that loss immediately by the repair cost or you can realize it at the point of sale. In either case you experience that cost of eventually.

the difference is if you fix it you get to enjoy having it work. So basically it's stupid not to fix things.

tbone75

Thanks MBB - I totally agree.

any actual advice on my issue?

olds442111

I've had to change the Xfer case electric motor on many. Just my $0.02

tbone75

Thanks Olds - I've seen alot online about that motor. I doubt its getting power but at some point I'll get 12v to the 2 wires going into that motor to see if anything moves and go from there. I have hit it with a rubber hammer-

Jbrew

If the GEM isn't sending ground there in and most likley lies the problem. So did this just start ? Describe the indicator light history, the illumination characteristics and how long this has been occurring. It may help determine or support the direction I think you should take.

tbone75

Thanks Jbrew- Just started a few days ago. switched it in 4hi to get up my drive and I believe it went in. next day switched back to 2hi and 4x4 light has stayed on since and nothing happens when moving switch. Its in 2hi but I'm not sure if that happened when I used the switch or if this malfunction put it back before that.

tbone75

I've suspected the GEM since the failed solenoid ground test. Just want to make sure a bad TC shift motor or something else wouldn't cause GEM to act that way.

Thanks

Jbrew

So your not totally sure it went into 4wd and out again to get up the drive when you used it ?

Regardless, if tested for grounds at the appropriate time and it's no longer sending..... if the switch passes testing like you said, then it's most likley the GEM. Your going to have to dry it out, inspect for water intrusion while dismantling. Submerge the GEM in rice to suck the moisture from it.

Contact user white89gt here, -

https://www.f150forum.com/private.php?do=newpm&u=225496

He's a frequent user and can explain the procedure with photo's as he documents fixes very well and thoroughly. Post your thread link and ask for his assistance, -good guy.