hpistar25

Just need a simple question answered. Does the GEM module on a 98 f150 4.6 4x4 give power to the the 4x4 solonoid at the T case when you flip the 4x4 switch on the dash?

Austin97

Yes.

hpistar25

all my relays and fuses are fine but my 4x4 light wont flip on and the t case solonoid has no power to it. saw on another thread a guy with the same problem and he replaced the GEM and it didnt fix his problem. id hate to eat 300 bucks on a GEM and it not fix my problem

Austin97

Just cause it controls it doesn't mean that will be your problem. The GEM gets a signal from the 4x4 switch and controls the transfer case shift relay module which shifts the transfer case. So you've not only got the GEM but the switch and t-case shift relay module and all the wiring and several fuses that can cause the problem.

So now you've got to rule things out. First things first, check fuse 17 under the hood and fuse 12 under the dash. Then I would use a volt meter to first check that there is power at pin 3 then measure the resistance between the two dark blue wires at the switch, pin 3 and pin 2. The three positions of the switch should read 3.9k, 1.1k and 360 ohms. If they aren't then you have a bad switch.

If the switch is good you need to make sure the GEM is outputting the ground signals to activate the relay that shifts the t-case motor. Orange/light blue is the wire for high and brown/white is the wire for low, they should be pin 16 and 17. Check those two wires for voltage when the switch is in those positions. You should check them both at both high and low just in case i'm wrong about which is high and low. If neither of them have voltage that doesn't mean it's bad. The wires should be nothing or power at rest and ground in high or low so take your meter and again set to ohms put one lead on a good ground and probe the wires with the other. In high and low you should read 0 ohms on the orange in high and brown in low. if the wires are going to ground the GEM is good and you need to move on to the relay.

So that should be enough to keep you going for a while. Let me know how the diagnosis goes.

hpistar25

when you say "pins" are you talking about the pins on the Gem? and btw, YOU HAVE GIVEN ME THE BEST INFO IN THE PAST 4 WEEKS ON THIS ISSUE! THANKYOU so much

Austin97

The connector pins. Where the wires go into the connector. You need to test everything with the connectors connected. Back probe the wires at the pins right at the connector. Sometimes you need something small like a paper clip to stick into the back of the connector so you can get the reading. As you can tell it's not exactly a basic diagnosis. What really sucks is that the shift relay module is up in the dash. Hopefully you can get to it by pulling the radio but I'm not sure.

Forgot to say, the second paragraph I'm talking about the pins on the switch connector. In the third I'm talking about the GEM.

hpistar25

so that shift relay module is that lil black box in the center of the dash kinda above the radio which involves taking almost the entire dash apart to get to? haha greeeat. this is starting to suck.lol

Austin97

I've never replaced one. But I'm sure it's no picnic. Hopefully it's the switch and you wont have to mess with it. I don't think they go bad often, I've never heard of anyone replacing it specifically.

kcautoparts

Hi guys I just wanted to let you all know that i just received a large order of GEM Modules for all kinds 1997-2003 f150's f250s and Expedition's.
Here is my ebay screen name " kcautoparts " . I am here to help out with your GEM needs. I have many diffrent part numbers in stock and listed check me out!! Thanks

hpistar25

The GEM was bad. For idk what reason. But after swapping it out my 4x4 works again. Thank you