1995 Ford Ranger 4 Wheel drive shifting faulty

I need to ask a question or two first so I can try to help. I need to know if the 4x4 lights come on on the dash. Do you have a lever to put it in 4wd or is it buttons on the dash to push? I also need to know if you have a digital multi meter to run some tests on the system to determine if it is the GEM or the T-Case Shift Motor? Get back to me so I look up the tests and walk you through them.

Hi
Thanks for getting back.
3 Position switch on dash is not problem. Brand new. Tcase motor activates when hotwired directly from battery.
Dash illuminates with 4wheel hi/lo lights on start up, then goes out.
Switch light never illuminates.
Have multimeter.
Any help figuring out if its Tcase motor or GEM is much apprecated!!
Brad Chute

Ok first gain access to the GEM and use the pic below to do a couple of tests. We are going to check the white wire with the light blue stripe on it. Now unplug the C3 connector from the gem and check the resistance of this wire between the 4x4 switch and the GEM term number 8, it should be less then 5 ohms if more then check for a break in the wire. Now plug it back in and do a voltage test between the white wire with the light blue stripe and gray wire with the red stripe. Should be battery voltage with key on engine off, if not look for a short in one of the wires. Now unplug the C3 connector again and check for continuity between ground and the white wire with the light blue stripe, if continuity is pressent then look for the short or where it is touching ground, if no continuity then we go to the next test on the GEM. You will need to be a little patient as this is long test. Get back to me with what you find here and we will go to the next step from there..

FRI PM:

Thanks for very clear explanation/diagram! Will start checking in early AM and relay results.
Brad

Ok sound good. Let me know what you find.

Thanks again for very clear procedure/diagram.

Ok first gain access to the GEM and use the pic below to do a couple of tests. We are going to check the white wire with the light blue stripe on it. Now unplug the C3 connector from the gem and check the resistance of this wire between the 4x4 switch and the GEM term number 8, it should be less then 5 ohms if more then check for a break in the wire.
RESULT: NO discernable continuity

Now plug it back in and do a voltage test between the white wire with the light blue stripe and gray wire with the red stripe. Should be battery voltage with key on
RESULT: Found two grey wires no red stripe on either, but by working at corresponding grey/red wire at switch switch figured out which was switch leg. Only found 3.7 volts with key on (Car not on).

Now unplug the C3 connector again and check for continuity between ground and the white wire with the light blue stripe, if continuity is pressent then look for the short or where it is touching ground, if no continuity then we go to the next test on the GEM.
RESULT:Key off: 4.17 K ohms
Key on: 5.80 K ohms

You will need to be a little patient as this is long test.
NO PROBLEM! PATIENCE I GOT-- EXPERIENCE AND SPECS I DON'T!
Talk to you soon.
Brad Chute

Ok check that gray wire with only 3.7 volts for any fraying or breaks as it sould be battery voltage. Let me know if you find anything and we will go from there.

Thanks!
Maybe stupid questions but:
Can you give me a rough idea of the scope of the search?
Should I bust apart taping on harness as necessary and just keep following?
Will it run around dash then into engine compartment? Will it go all the way to t-case?

Hey

By the way, I know shop time is worth 80-90 bucks an hour and a diagnosis at least that, so at the end of all this if I manage to find the problem, you guys tell me what kind of time you have into this problem and I'll add to the deposit

Anyway:
There is 12.0 (a little less that batt voltage) at grey terminal harness side (#14) on GEM.
Also, when brake is depressed with engine running there is about 11.6 next terminal over so it seems like GEM is getting that signal.
The selector switch is only receiving 3.4 volts from the GEM.
When HI is selected the voltage drops to 2.4
When LO is selected it goes to 1.2v
The voltage remains at 0 at two other wires (red/blk stripe and green/red stripe) throughout .
I tried supplying 12v to white/blue stripe connector on switch (feed from GEM) and provided good ground to solid black at switch. No lights, no shifting.

Talk to ya soon.

Sound like the GEM is not sending the signal for the 4x4. Before we say it needs to be replaced I would like to check the transfer case relay module. Use the pic below for reference. Now with key off disconnect the transer case relay module. CHeck for continuity between term 8 and 1. If there is continuity then the transfer case relay is the problem and needs to be replaced. Unfortunitly it don't tell me where it is. Here is the pic of the connector.

When you said check the transfer case relay module, I'm thinking you mean it's a connector location on the GEM and not a stand alone unit??

If it's part of the GEM harness, I should be able to match up pic you sent with some plug on the GEM even without a location.

Thanks!

Ah, found transfer case relay by flashlight. It lives right behind the 4x4 module. About the size of pack of cigs. Undid the clip and tested between Pin 8 and Pin 1. There is NO continuity.

Talk to ya when you get a chance

Brad Chute

Ok sound like the GEM according to the tests. Let me know how it goes. Have you checked the transfer case shift motor?

Yeah checked motor first thing. Hot wired it and it spins fine. That doesn't exclude it absolutely though. It could be a problem with the shift position sensor inside. Maybe its not sending feedback (or incorrect feedback--smushed bump stop??) to the GEM so GEM won't issue shift signal. GEM or relay is clicking (now!) on start up, whatever that means.
Asked my mechanic and he said he did probably fifty pickups with similar and he changed motor after screwing around for awhile and that always fixed the problem.
So ordered motor for $90 bucks on line. We'll see.
I don't feel too bad throwing parts at it at this point because even you guys are having some questions about exactly what it could be.
If its not the motor I'll also swap out the GEM. Many thanks.
Will be in touch!

Yes the motor is most common that is why I didn't want to jump on the GEM being the problem. Anyway I think that will fix it too. Let me know how it goes.

Hey, thanks again for getting back.
Snapped in new motor($90) and it's not the problem. Didn't install, just plugged it into in harness, clutched, braked and hit 4x switch. Nuthin. Don't think (electrical checks bear this out) that it's getting signal.

Weird thing though: The new motor has 7 wires, the old one had 8. The 8th wire (not on new one) runs from car wiring harness connector into transfer case through a rubber bushing. Don't think it's speed sensor. Can't seem to find any mention anywhere in parts on line, or at dealer or literature of an 8 wire connector.
What is it for? Do I need it??

Per your advice, ordered a GEM online (Conquest Auto $200).

If it's not the module or switch or GEM, it's gonna be a royal pain to find.
Will let you know how it goes!

Ok sounds good let me know how that goes. If that don't fix it then there has to be a bad wire somewhere. Any lets hope not.

Hey,

I am such a dips&%t!
When I hooked the new motor I got it in mail into the harness the first night(Just laid it on ground under truck), I hit dash switch and leaned out of truck to see if it engaged. It didn't, so I ordered a GEM for $200.

Right after I ordered the GEM, I started wondering if I had depressed the clutch and the brake all the way when I hit the switch the night before. I reattached the new motor to harness and made sure I did both.
Back in business! The new motor spins on command.
I canceled the GEM order. Now I just gotta install the new motor.
So even thought the old motor spins, the shift selector sensor is probably faulty and not sending correct GO signals to the GEM.

Sending along some more dough. That will bring total to half hour of shop time. Hope that works for you guys.Thanks for all the help with this.
Brad Chute

Great glad to hear it is working again. You have pride in doing it yourself too. You have a great day and if you need anything else just ask.