ESOF Woes - This one is complicated
#1
04-09-2015, 10:13 PM
ESOF Woes - This one is complicated
I bought an Excursion this past Monday - a 2000 Limited V10 4wd 4.30 gears. Only 55k miles on it and in super nice shape. Anyways, I noticed that the 4wd would not engage during the test drive. I pointed it out to the salesman and managed to talk them down quite a bit on the price because of it. I figured it would be something dumb like a fuse or relay.
Here's where I'm at so far:
Found blown fuse number 104 in the underhood fuse box. With the ignition off, trans in park, and the 4wd switch in the "2wd" position, I replaced the fuse and instantly relays and solenoids went crazy and the truck shifted itself into 4-LO. I pulled the fuse and started examining the shift relays. Both relays tested good. I started probing the relay connector and found that the coil terminals (85 and 86) for the High-to-Low relay are always energized whenever fuse 104 is in place. Looking at the wiring diagram, this points to the GEM grounding the relay coil to close the relay. I checked for voltage again at the relay coil with ignition on and 4wd switch in every position. Not only is the High-to-Low relay always energized, but the Low-to-High relay never gets energized. Next I pulled the connector from the GEM and sure enough the High-to-Low relay de-energized. This test eliminated a short-to-ground in the harness being the cause.
I then pulled the GEM out to take a look at it. Its been my experience that control modules only fail when they get wet or a resistor or capacitor blows up. My GEM showed no signs of either. The circuit board looked just like the day it left the factory. All other GEM functions work perfectly. I'm very hesitant to replace the GEM since it looks good and otherwise works good.
Next I tried hotwiring the shift motor to get the truck back into 2wd so I could at least drive it. To my surprise, the motor would not move in either direction when I applied 12v to the terminals. I also checked continuity between the relay connector and the motor connector and all was good. I removed the motor assembly from the transfer case and noticed it was a reman part. So apparently someone has already had it out at some point. The motor has approximately 23,000 ohms resistance across the terminals. I'm no electrical engineer, but I believe that to be wildly out of spec and the reason it doesn't work.
So I've identified one bad part. However, I still have the issue of the High-to-Low relay is always energized if fuse 104 is in place. I can't think of a reason why the GEM would constantly want that relay energized. I'm afraid putting a new motor in isn't going to fix the issue.
If I start throwing parts at it, I'll $400 into it pretty easy between a GEM and shift motor. My local junkyard has 2 manual shift NP-273s out of F-250s - my choice for $200 each. I could probably talk them into throwing in the shift lever and linkage. Add a set of manual hubs and I'd be right about at the $400 I'd spend throwing parts at the ESOF. My Excursion has the cutout in the trans tunnel for a lever and the 4R100 has the linkage mounting boss on the side of it too. It should be a plug and play swap. I've always had manual shift t-cases in my other Fords and I don't see why I wouldn't like it in the Excursion.
Any other ideas to fix the ESOF? Any reason not to do the manual t-case swap?
Here's where I'm at so far:
Found blown fuse number 104 in the underhood fuse box. With the ignition off, trans in park, and the 4wd switch in the "2wd" position, I replaced the fuse and instantly relays and solenoids went crazy and the truck shifted itself into 4-LO. I pulled the fuse and started examining the shift relays. Both relays tested good. I started probing the relay connector and found that the coil terminals (85 and 86) for the High-to-Low relay are always energized whenever fuse 104 is in place. Looking at the wiring diagram, this points to the GEM grounding the relay coil to close the relay. I checked for voltage again at the relay coil with ignition on and 4wd switch in every position. Not only is the High-to-Low relay always energized, but the Low-to-High relay never gets energized. Next I pulled the connector from the GEM and sure enough the High-to-Low relay de-energized. This test eliminated a short-to-ground in the harness being the cause.
I then pulled the GEM out to take a look at it. Its been my experience that control modules only fail when they get wet or a resistor or capacitor blows up. My GEM showed no signs of either. The circuit board looked just like the day it left the factory. All other GEM functions work perfectly. I'm very hesitant to replace the GEM since it looks good and otherwise works good.
Next I tried hotwiring the shift motor to get the truck back into 2wd so I could at least drive it. To my surprise, the motor would not move in either direction when I applied 12v to the terminals. I also checked continuity between the relay connector and the motor connector and all was good. I removed the motor assembly from the transfer case and noticed it was a reman part. So apparently someone has already had it out at some point. The motor has approximately 23,000 ohms resistance across the terminals. I'm no electrical engineer, but I believe that to be wildly out of spec and the reason it doesn't work.
So I've identified one bad part. However, I still have the issue of the High-to-Low relay is always energized if fuse 104 is in place. I can't think of a reason why the GEM would constantly want that relay energized. I'm afraid putting a new motor in isn't going to fix the issue.
If I start throwing parts at it, I'll $400 into it pretty easy between a GEM and shift motor. My local junkyard has 2 manual shift NP-273s out of F-250s - my choice for $200 each. I could probably talk them into throwing in the shift lever and linkage. Add a set of manual hubs and I'd be right about at the $400 I'd spend throwing parts at the ESOF. My Excursion has the cutout in the trans tunnel for a lever and the 4R100 has the linkage mounting boss on the side of it too. It should be a plug and play swap. I've always had manual shift t-cases in my other Fords and I don't see why I wouldn't like it in the Excursion.
Any other ideas to fix the ESOF? Any reason not to do the manual t-case swap?
#3
04-10-2015, 12:38 PM
That thread didn't tell me anything I hadn't already learned reading the internet. My problem can summed up as follows:
1. I have a known bad shift motor.
2. It appears that my GEM has an internal short-to-ground in the high-to-low relay driver circuit.
I'll try to take the GEM out again this weekend and see if the short to ground isn't right at the connector such that I could fix it.
Until I get the GEM to behave, I don't see the point of wasting $100 on a shift motor.
If the GEM is shot, the $300 replacement cost is prohibitive enough to make me want to do the manual t case swap.
1. I have a known bad shift motor.
2. It appears that my GEM has an internal short-to-ground in the high-to-low relay driver circuit.
I'll try to take the GEM out again this weekend and see if the short to ground isn't right at the connector such that I could fix it.
Until I get the GEM to behave, I don't see the point of wasting $100 on a shift motor.
If the GEM is shot, the $300 replacement cost is prohibitive enough to make me want to do the manual t case swap.
#4
08-26-2015, 07:53 PM
That thread didn't tell me anything I hadn't already learned reading the internet. My problem can summed up as follows:
1. I have a known bad shift motor.
2. It appears that my GEM has an internal short-to-ground in the high-to-low relay driver circuit.
I'll try to take the GEM out again this weekend and see if the short to ground isn't right at the connector such that I could fix it.
Until I get the GEM to behave, I don't see the point of wasting $100 on a shift motor.
If the GEM is shot, the $300 replacement cost is prohibitive enough to make me want to do the manual t case swap.
1. I have a known bad shift motor.
2. It appears that my GEM has an internal short-to-ground in the high-to-low relay driver circuit.
I'll try to take the GEM out again this weekend and see if the short to ground isn't right at the connector such that I could fix it.
Until I get the GEM to behave, I don't see the point of wasting $100 on a shift motor.
If the GEM is shot, the $300 replacement cost is prohibitive enough to make me want to do the manual t case swap.
#5
08-26-2015, 08:31 PM
Lead Driver
I have always wished I had a manual shift t case anyhow so I would just convert it.
But back to you, If you were to buy a reman gem don't you still have to take it to a dealer to be programmed for your vehicle ? So you have the price of the Gem + 1 hr shop rate ( for 15 minutes of work )
You say the low shift rely is always energized. That sounds like a problem to me. Can you swap the rely for a know good part ? Or find the rely test procedure to confirm your rely is still good. What I am getting at is the gem could be fine and the relay is bad ? Also is there a procedure to test the gem output to the shift relay ?
But back to you, If you were to buy a reman gem don't you still have to take it to a dealer to be programmed for your vehicle ? So you have the price of the Gem + 1 hr shop rate ( for 15 minutes of work )
You say the low shift rely is always energized. That sounds like a problem to me. Can you swap the rely for a know good part ? Or find the rely test procedure to confirm your rely is still good. What I am getting at is the gem could be fine and the relay is bad ? Also is there a procedure to test the gem output to the shift relay ?
#6
01-02-2017, 12:30 PM
Well let's bring this old thread back to life for a happy ending! I've been happily driving the X around as a 2wd for the past two years. Time flies I guess. A couple weeks ago I finally got around to feeling like working on the 4wd issues. I draggged out the ford service manual and EVTM and ran through the entire troubleshooting procedure. This confirmed my previous diagnosis of bad shift motor and an internal short in the GEM. Picked up a new shift motor and searched ebay again for a GEM. Got lucky this time and found several for less than $200. I guess more X's are making their way into junkyards at this point.
Everything works properly now! Boy did that did put a smile on my face listening to the relays and solenoids work properly when I first tried the 4wd switch! Just thought I'd finish this thread out for future searches.
Everything works properly now! Boy did that did put a smile on my face listening to the relays and solenoids work properly when I first tried the 4wd switch! Just thought I'd finish this thread out for future searches.
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