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4 wheel drive question


Pix3L8

Well-Known Member
Supporting Member
Joined
Jun 13, 2016
Messages
134
City
Connecticut
Vehicle Year
1989
Engine
2.9 V6
Transmission
Manual
Total Lift
6
Hi, guys just had a quick question. I recently swapped my bronco from an A4ld transmission to a fm145 manual transmission. when I did this I reused the original bg 1350 transfer case. A little while after the swap my "shift on the fly" 4x4 stopped working, so I replaced the t-case motor. When I did this I got my 4x4 back but only 4-high, when I try to engage 4-low the light blinks. The question I have is, the old motor had 3 wires going to some sort of sensor on the transfer case BESIDES the plug to the harness, the new one does not, I'm wondering if I need to splice them into the new motors plug and this could be the reason it won't go into 4-low?

side note- the new manual transmission has no sensors hooked up to it, no neutral switch or anything (had to bypass it) none of the diagrams online show these three extra wires on the transfer case, could it be some sort of position sensor? 1989 BII when I took the old motor off I had to cut these 3 extra wires because there was no way to unplug them they go straight into the transfer case.
 
This is a long shot, but when you try to go into 4Lo are you moving? My 1990 owner's manual says that to change from 4Hi to 4Lo and back again, you must come to a complete stop. You can shift from 2wd to 4Hi while you're moving, but not 4Hi to 4Lo, and not from 4Lo to 4Hi.
 
Im pissin in the dark here. But im guessing that it wont go into 4 low because it doesnt know the trans is in neutral. Youll pry have to figure out how to splice the neutral switch in.

Or swap in a manual Tcase.
 
Im pissin in the dark here. But im guessing that it wont go into 4 low because it doesnt know the trans is in neutral. Youll pry have to figure out how to splice the neutral switch in.

This wouldn't be hard, there is a neutral switch on the 145, he would just have to run the N wires from the auto wiring to that switch.

Or swap in a manual Tcase.

This would be the better option.
 
I was kinda hoping it wasn't that sensor and I wouldn't need to splice but ill give it a try. Also, I tried both moving and stationary shifting into 4 low.

also, the 4x4 control module behind the driver's seat doesn't blink when I do a self-test so it knows something is wrong, the light just stays on.
 
I managed to find a diagram online, the three wires I'm talking about are the wires going to the magnetic clutch or the speed sensor
 

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I was kinda hoping it wasn't that sensor and I wouldn't need to splice but ill give it a try. Also, I tried both moving and stationary shifting into 4 low.

also, the 4x4 control module behind the driver's seat doesn't blink when I do a self-test so it knows something is wrong, the light just stays on.

It wants to see the trans in N when doing the 4-low shift because the T-case has to go through it's N range to get to low. If you are stopped in gear when the T-case hits N the trans and forward components will start spinning again and grind the T-case.
 
when you look at the shift controller...theres a series of plugs....

find b1. usually its either red/white or red light blue. its the
7-e4dba2c177.jpg
normal switch ground circuit via neutral...


you can simply ground it with a momentary switch to shift in and out of 4 low.

hold it when you press 4 low....or just leave it grounded.....but if you leave it grounded you can tear shit up that way
 
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thanks for the info guys
 
It wants to see the trans in N when doing the 4-low shift because the T-case has to go through it's N range to get to low. If you are stopped in gear when the T-case hits N the trans and forward components will start spinning again and grind the T-case.

Even in park my manual 1350 didn't want to go into low. I suppose the shafts couldn't shift around to line up when the trans output was locked in park... that's my theory anyway.

When the book said neutral, it had to be in neutral.
 
Even in park my manual 1350 didn't want to go into low. I suppose the shafts couldn't shift around to line up when the trans output was locked in park... that's my theory anyway.

When the book said neutral, it had to be in neutral.

You are probably right.

I remember one time I was in a truck with an auto trans and a manual t-case, and wasn't thinking when I tried to slip it into 4-low in D.
 
You are probably right.

I remember one time I was in a truck with an auto trans and a manual t-case, and wasn't thinking when I tried to slip it into 4-low in D.

I'm guessing one of two things happened. Either it just wouldn't go in, or somebody is still finding transfer case parts years later.
 
When I hear stories like these, I'm glad I haven't shifted the Rat out of 4 low in 2 yrs :D
 
Well, not if you unlock at least one hub. And are willing to go along slowly.
 

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