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4x4 issues after M5OD swap

Gadget X

Elite Explorer
Joined
March 13, 2007
Messages
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City, State
Gibsonville, NC
Year, Model & Trim Level
'94 XLT 5-speed
Ok, finally got tired of throwing parts at my A4LD, and swapped it out for a manual this weekend! All went good, but when I put it all together, I don't have 4-low. I can engage 4wd just fine, but low doesn't work at all. And yes, I am in neutral with the brake and clutch pressed. I did end up having to use my auto ecu, because the manual ecu that I got made my truck run like utter crap! Don't think so, but could that cause my issue? Also, what is "different" between the auto and manual ecu? Thanks!
 



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Did you happen to remove the shift motor when you pulled the tcase off?
 






Does your M5OD have a neutral switch? Did you hook it up?
 






No, t-case stayed completely intact, except for the nasty fluid in it, which I changed. My confusion lies with why it will go into 4wd just fine, but 4-low won't engage now.
 






Yes, I hooked up the switch on the clutch pedal, have to press the clutch before the engine will crank. Also used the manual transmission wiring harness, and both sensors on the transmission are plugged in.
 






Yes, I hooked up the switch on the clutch pedal, have to press the clutch before the engine will crank. Also used the manual transmission wiring harness, and both sensors on the transmission are plugged in.

99% of the time it's the neutral switch on the trans that gives people this same problem when they do the M5 swap.

My work around was to find and cut the red w/ white stripe wire at the shift computer. Then ground the end going to the computer. That will give you the ability of shift on the fly low range. (Kids, don't try this at home.)
 






Are you talking about the 4x4 module in the rear drivers quarter panel? What on the neutral switch could be causing the problem? Do the switches go bad, or is it a connection issue? Could me using the auto trans ecu be causing this? Thanks again!
 






Did you happen to remove the shift motor when you pulled the tcase off?

I asked this because the motor alignment can cause issues with no 4lo. Possibly the motor got bumped just enough while removing and reinstalling the tcase to shift the motor a hair.
 






No, it was removed, handled, and reinstalled gently. (I had to rebuild the darned thing once, don't want to again!) It goes into 4x4 with no hesitation, first push of the button, but 4-low, not even a click from the 4x4 module.
 






You can shift into 4Hi at any time, the computer doesn't care what your speed or selected gear is. However, the computer requires you to be in neutral (brake doesn't matter so much, just neutral). It's probably your neutral switch not being hooked up or hooked up right.

I think there's a vehicle speed sensor as well, it might be tied into the 4x4, requiring you to be under a certain speed when shifting into 4Lo.
 






You can shift into 4Hi at any time, the computer doesn't care what your speed or selected gear is. However, the computer requires you to be in neutral (brake doesn't matter so much, just neutral). It's probably your neutral switch not being hooked up or hooked up right.

I think there's a vehicle speed sensor as well, it might be tied into the 4x4, requiring you to be under a certain speed when shifting into 4Lo.
I understand all that, and everything is hooked up correctly. Is there a way to check to make sure the neutral switch functions as it should, and is it replaceable if not? Thanks.
 






I read somewhere once that if you can start the vehicle in anything other than Park or Neutral (in your case, anything but Neutral) then the Neutral Switch is buggered.
 






I read somewhere once that if you can start the vehicle in anything other than Park or Neutral (in your case, anything but Neutral) then the Neutral Switch is buggered.

If that were the case, the Clutch Triple Function Switch would be stuck closed and the T-case would be able to shift into low.



I would throw the clutch Triple function jumper back in... That would be a simple way to test that.
The neutral switch on the trans can be tested by disconnecting it and testing for continuity across the 2 pins on the switch while in neutral. Continuity = its good, no continuity = its bad.
 






Maybe there was a difference in the transmission wiring harness'? If they are from different years, the pins could be in the wrong place. Just a random thought.
 






The wiring harness and the transmission are both from a 93. Is there a difference between 93 and 94? Everything looks identical, wiring-wise. I even made sure that it had the same O2 sensors and egr stuff. Oh, and by the way, my cruise control does work, releasing if I touch the brake or the clutch. I'll check for continuity at the neutral sensor tonight or tomorrow. Thanks!
 






There very well could be, off hand I don't know for sure though. I ran into differences between a 91 and a 92 before while doing an engine swap on one of my old Rangers. Just had to move some pins around in the connector. The easiest way to tell would be to compare the wiring schematics between the two. It only takes one wire out of place to make it not work.
 






Ford changed the harness in the early 90s when they went to 2 O2 sensors. They also changed the connector at the same time. If it plugged in... It's the right one.
 






Ford changed the harness in the early 90s when they went to 2 O2 sensors. They also changed the connector at the same time. If it plugged in... It's the right one.

Well that's good to know! Also, what's the difference between the auto ecu and the manual ecu? I read somewhere that the timing and idle speed were set differently, but not sure what effect that would have on the way it runs.
 






Well that's good to know! Also, what's the difference between the auto ecu and the manual ecu? I read somewhere that the timing and idle speed were set differently, but not sure what effect that would have on the way it runs.

AFAIK, the auto ECM has a more aggressive timing curve (nothing really noticeable). The idle is a little higher on the auto ECM to compensate for the load of the torque converter. There is also something different about the way and speed it returns to idle vs the manual ECM... You may find it doesn't drop back to idle right away when you're coasting in neutral. There's probably some other differences, but those are the big ones.
 



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