hello. This is my first time posting a question. Thanks to anyone who can help me. My truck, 1997 f150 4x4, is not shifting into 4hi or 4low. Here are some things I have already checked. No ground from gem on either vaccum solenoid. No power from gem to shift motor. dash light not on< but do come on when i start truck and go out after truck starts. I pulled gem and found no corrosion on terminals. shift selector switch checks out ok. I checked the resistance in each range and compared them to specs found in this forum. All fuses check out fine. I have unhooked the battery over night in hopes of resetting gem. still nothing. I checked the contact plate location by comparing which wire is grounded and which isnt. it is in 2wheel drive. the gem was manufactured in 1996. the shift motor has the blue cover on it. I can't find any outputs from the gem regarding the 4x4. what do I do next? HELP. thanks again

 

i think it could be a bad transfer case shift motor cause if the light doesnt come on when shifted this usually mean the transfer case isnt engaging, flip the switch and reach under the truck and see if you can turn the drive shaft if u can its not engaged if its solid its engaged hope this helps

 

I flip the switch and nothing happens.No relay sound, I checked power leads to motor. No voltage to motor. Its like the gem is dead. Thanks

 

did u check the fues under the hood there should be a 4x4 fues it could have blown

 

Sorry for taking so long replying. I checked all fuses under hood. Yesterday I removed the fuse box and gem again to check for voltage going into gem. My hands are so big I couldnt check it to my satisfaction. as far as I can tell, the gem is getting power from the distribution power box. Question: If the contact plates in the transfer case motor sends a signal that the gem doent recognize. Will the gem shut down? Thanks for the help. I am really frustrated, we just got a foot of snow dump on us aand me without 4x4.

 

Hi Hawk,I'm Jerry.I'm having the same problem with my 98 ford f150.Currently the truck is in the shop for this problem,(under warrenty).If they can fix the prombem ,I'll write back to let you know,if you could do the same for me, Thanks Jerry

 

Same problem here with 03. 4x4 light is on only when truck is started. Nothing when 4x4 switch is turned, no switching sound or anything. Checked all fuses and disassembled switch and cleaned up. Any info would be greatly appreciated.

 

Hawk2010,

Check fuse #23 at the fuse box in the cab and #17 under the hood. When you had the fuse box out did you see any signs of corrosion? The GEM is fastened to the back of the fuse panel and water from a windshield leak drips down and corrodes the connectors.

.

 

Thanks Jerry and trucee, I will post what I find out on my truck. Please do the same. JMC, I went out and checked Fuses 23 and 17. they were both good. I changed them anyway, you never know, could of been dirty, When i had gem out, all the connections looked like what I would expect in a new truck. No corrosion at all. Im hoping the shift motor is sending a mixed signal to the gem. causing gem to shut down. Have you ever heard of this? what is the usual part that is bad, shift motor or gem? I have enough money for 1 but not both. Thanks again.

 

Trucee, Try disconnecting battery for 20 minutes to reset gem. The switch on dash tells gem what range to be in. gem then engaged magnet in transfer case and also sends 12 volts to motor on transfer case. When contact plates in motor determine that the shift is complete it sends a signal back to gem and the gem removes power and engages front axle soleniod. Only then will the 4x4 light come on. Alot of people have trouble with corrision on all connections in this system. Check wire connector close to motor. clean and reconnect. disconnect battery for 20. and retry. let me know what happens. This didnt work on mine but I hope it works on yours.

 

When working normal I would hear the relays switching when switched to 4x4. I do here anything at all now. If the shift motor was bad wouldn't you still hear the switching of the realys?

 

Yes and No. think of the shift motor as 2 parts. 1 being the motor itself. the other being the contact plates. the actual motor could fail, you would hear relay clicking until gem shuts it down. if the contact plate sent a bad signal, the gem would shut down. no lights, no relay clicking , nothing. Is your truck stuck in 4 wheel drive? Im not an expert, im like you just trying to figure it all out.

 

Does anyone have an electrical schematic of the 4x4 system? I ohm'd out the switch (4x4 one on the dash) but you can't because of a couple of components on the board. I have a good ole Haynes manual but it does not show any of the 4x4 stuff. I would love to know what pins or wires to check on the shift motor for 12v when it is to shift.

 

Hawk2010
It is not stuck in 4x4. At this time I wish it was with all of the snow we have recently had. Thanks for all of your feedback!

 

Check sskulley folder's. He has a lot of good stuff in there. Thank You sskulley for putting that in folders