Shifting problem with AW4

Guys,

I am going nuts here, my symptoms are. The transmission either gets stuck in 1st or third gear, here is what I have done so far:

1. replaced the Throttle Position Sensor
2. removed and cleaned the Nuetral Safety Switch
3. Adjusted the TV cable per the Haynes manual
4. Unplugged the TCU and manualy shifted the truck, works perfect shifts between 1st and 3rd like it should.

This last one points me towards the Transmission Control Unit being bad. Anyone have any other ideas?

Thanks,
Dan

It's a 1991 Cherokee Leredo (4 speeds)....

it could definately be a bad TCU

mine in my 96 went bad (all of the sudden for no apparant reason)

symptoms were very similar to yours...

luckily i have a buddy in the auto repair industry who was able to order the new TCU from the stealership at cost.

VERY easy install though

the whole unit is about the size of a deck of cards...

its a black box undet the glove box with some wire harness' plugged into it.

i think after u do the swap (if it IS in fact the TCU) u may need to flash the computer (either unplug the neg battery terminal for 15 minuntes, or preferably use an OBD-II computer on it

i would see ifu can plug in to an OBD II diagnostic computer first--to see if i can pull any fault codes.

good luck!!

CaptTrev

There's an in-line fuse -- 10A, I think -- wraped in tape just before the TCU, and there's another fuse for the AW-4 on the fuse block. It might be one of those.

mine was acting up by not shifting into nuetral when I would come to a stop it ended up beint the harness, but I niagnost it my fallowing the tips on this site that I found on thissite . fallow these and you should be able to get it done.

I think you can reset the computer by touching the positive battery cable to the ground post on the battery. Might want to double check with ryurabbit as that is where I got this info.


Good luck, Dan

BTW, if the TCU fuse is bad, It's not supposed to shift out of 1st gear. I was thinking of putting a switch in line to this fuse to keep my auto in 1st on demand.