New guy here, couldn't figure out how to create a signature so the truck in question is a 1991 F350 7.3 idi 4x4. I recently swapped in a zf5 to replace my old burnt out e4od. So the issue I'm having is I have no reverse gear while the T case is in 4hi, as I discovered today at a very bad time. Well I finally got unstuck so here I am. Reverse works fine in 2hi, I have not tried 4lo yet. All forward gear work fine in 4x4. I think today is the first time I've used reverse while in 4x4 since the swap, so I probably screwed something up, just can't think what. Trans input shaft is spinning but not putting any power to the wheels, just makes a grinding noise and a lot of vibration.

I have all electronics hooked up to the T case, it is the manual not the electric. I think the wiring harness on it is just for the lights on the dash anyways?

I have no wires hooked up to the zf5. My donor truck for the swap was missing the two wiring harnesses, I thought those were only for reverse lights, cruise control, and the neutral safety switch. Am I wrong?

Maybe theres some wiring I'm overlooking? I can't think of any other reason for reverse to fail in 4x4, aside from an internal failure on the transfer case, but then I would think I wouldn't be able to put power to the wheels in forward gears either.

Any insight to this problem would be greatly appreciated, Thank you!

 

It won't let you create a sig until after 25 posts. Sorry.
As far as the transfer case not working in reverse, that's weird. There's no electrical needed with a manual selector transfer case. The elec stuff is for the 4x4 light and ecu to know when it's in low range (supposedly the e4od changes shift points in low) and the zf only has a reverse switch for backup lights. I'd say something inside the transfer case got goofed up. But it's weird that it works in 2hi but not 4hi, because I thought it only engaged the front pto and nothing else, where low moves to another gearset after engaging the front pto.
Very interesting.

Back to top for you.

 

Thanks for the response Untamnd, I was hoping I had overlooked some wiring.
Well I know the pump retainer breaking loose and allowing the pump to spin on the shaft is a common issue with the bw1356. My truck has somewhere around 175k miles on the clock so its probably time to split the case and see whats going on anyway.
I'm tempted to just find an np205 but I really don't want to have to have driveshafts custom made again.

 

welcome to FTE
first thing i would try is making sure the t-case is completely in 4high. it may have been partially engaged, and when you put in reverse it popped out of gear. then when you put it in first it went in enough to move the truck.

my 88 diesel did that to me a few times.

 

I think you may be right tjc transport. I made the linkage myself and assumed it was fine because it is shifting into 4x4 and the light on the dash comes on. I will pull it apart tomorrow and shift it into 4x4 without the linkage on and see if that solves the issue.

 

Tjc you were right, my linkage was a little too short so it was partially shifting into nuetral. Why this only happened with reverse gear, I have no idea. Just glad it's not an internal issue. Thank you!

 

you are more than welcome.
i am glad it was an easy fix for you.