Need Help with 4x4.

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May 11, 2015 | 08:19 PM

jamesinmo

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Need Help with 4x4.

Just bought 1997 Expedition XLT 4x4. When I move the switch to A4WD the A4WD light comes on. When I move switch to 4hi or 4lo the A4WD light stays on and the transfer case does not make a shift… I think I hear a relay click four-five times when I move the switch to 4hi but then after it gets done clicking it won’t make that sound again until I restart the truck.

So I stupidly threw a new transfer case motor on it thinking it would fix it. It did not. So then I moved to switch, I tested the switch with an ohms meter and got the correct resistance at all positions.

From what I have spent hours researching online, this leaves me with the Transfer Case Motor Relay, and the GEM. Before I throw another part at this truck does anyone have any knowledge on the correct way to diagnose this system?

If i have this in the wrong forum, im sorry.

Thanks for all your help.
James

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May 11, 2015 | 10:59 PM

alloro

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From: 0,0,1

Check fuses 20 & 23 under the dash and 17 under the hood.
The pinpoint tests are quite long and you really need to have a factory service manual nearby in order to go through them all.

May 11, 2015 | 11:03 PM

FoxFord33

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From: Skiatook, OK

I believe that the system is vacuum-actuated. The problem could be with the diaphragms inside the hubs/axle. The lights on the dash will still come on, but it won't shift properly.

Also, you may already know this, but I'm gonna say it anyway because it gave me trouble before I looked it up: I couldn't get mine to shift out of 4lo because I didn't shift to neutral.

May 12, 2015 | 09:16 AM

alloro

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Quote:

Originally Posted by FoxFord33

I believe that the system is vacuum-actuated. The problem could be with the diaphragms inside the hubs/axle. The lights on the dash will still come on, but it won't shift properly.

That's part of the problem he is having, the dash light stays on A4WD no matter where the shift selector switch is.

May 12, 2015 | 09:18 AM

alloro

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Quote:

Originally Posted by jamesinmo

So I stupidly threw a new transfer case motor on it thinking it would fix it. It did not.

I gave this some more thought overnight. Where did you get the shift motor? There are contacts inside of the shift motor that control the dash lights. So if the motor doesn't shift, or if it shifts but the contacts wiring doesn't match what in your vehicle, then the dash lights will never change.

May 12, 2015 | 07:48 PM

jamesinmo

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Hey all,

So I fixed it. It was the transfer case motor relay. I am going to write up what I did so that it might help someone else; I know I didn’t find anything like this online.
Symptom: NO POWER AT SHIFT MOTOR BETWEEN YELLOW AND ORGANGE WIRE.
Diagnosis:
1. Check transfer case motor relay power. This is the two G/LG wires attached to the relay you should see batt. Voltage when you put on lead on one of the green wires and ground. If you have power then fuse 17 and circuit in power distribution block is good.

2. Put key switch in hot/run position. I forgot which one of this test I did, so do both. What you’re looking for is just a signal from the GEM telling your relay to give power to one of the poles on the motor. If you get no voltage after making the switch to 4x4hi then you know your GEM is ok and giving the TCMR a good signal.
a. Probe the small O/LB and GROUND you should see batt voltage, then switch the mode switch on dash to 4X4hi you should see no voltage.
b. Probe the small BR/W and GROUND you should see batt voltage, then switch the mode switch on dash to 4X4hi you should see no voltage.
3. Disconnect relay. Correspond which wire goes with which terminal on the Relay. Check for continuance between Yellow/Ground pins and then check for continuance between Orange /Ground pins ON THE RELAY. This HAS to be done with the relay disconnected.
a. If you don’t get continuance on one or both then your relay is shot.

Thanks all,

James

The Transfer Case Motor Relay is located under the dash. Its the grey one in the back.

This is the interior of the TCMR. You don't need to take it apart just wanted to show you what it looks like.

Transfer Case wiring diagram that was really helpful.

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