Corey,

You might try posting this over in the Bronco II forum. The Big Bronco and the "Deuce" were/are very different models. Just an educated guess here since I know very little about these rigs but if the O/D has a manual shut-off (switch either on the dash or on the shift lever) you may be dealing with something as simple as a bad switch or at least one that is only working intermittantly.

 

hey guys.
i was wondering if you could help me. i have an 1986 ford bronco 2 XLT 4x4 with an auto transmission. the problem is that the trany will not shift into overdrive. but the weird thing is that it was actually working the other day for the first time since iv owned it. now i know that the trany in this kind of bronco sucks A4LD i think. but could someone please help me i would like to keep my bronco for as long as i can.

thanks
coreyh
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Assuming it's the original style A4LD that came out in '86, 3-4 shift is vacuum controlled. Make sure the vacuum line to the modulator is clear and intact. Beyond that it would likely be something internal -- either hydraulic or mechanical.
Is it possible they've put a newer A4LD in it (with an electrical 3-4 shift control)?

 

couldnt hurt to replace the trans fluid and filter while your at it