msb454
New Member
Ok, I have a electrical gremlin that I have been chasing for the last 2 months on a 2000 expedition EB. The issue I have having is the shift motor not trying to do anything. With shift motor solving the issue for 90% for the people with 4x4 issues, I blindly replace it. No luck. So I test power to the shift motor with a test light and I was getting power, so I thought it has to be and issue with the transfer case. To be sure, I took the shift motor off (while still plugged in) to verify its functioning properly. Again, no luck. So at this point I have power and a good motor with no operation. The only thing left is a ground. So I grabbed my meter and pierced the yellow and orange motor lead and tested power. Again no luck. So digging further, it turns out that I am getting 12v from each of the leads to chassis, with neither of them grounded. Now I open the dash to examine the I/O's of the shift relays. The grounds from the GEM are correct and only activating one of the two coils, but somehow both of the motor lead are going from normally grounded to 12+ when trying to shift into 4x4. At a off state, both motor leads ohm out to ground like they should. Just to clarify, I opened the relay and visually confirmed only one coil is activating. I am forced to think something is wrong with the shift relays, but it drives me crazy I cannot find anything physically wrong with it. Am I missing something? Any help might save the hair I have left! Thanks in advance for any input. Attached is the diagram I have been using.
