88 Transmission Won't Shift

[Roggesound]

I'm looking at buying my second Comanche, and the guy says the automatic transmission doesn't shift. He says he can drive it by physically moving the shift lever from 1-2 to 3 to D every time he stops. It's like his automatic transmission thinks it's a manual transmission.

 

Has anyone else had this happen? Should I just replace the transmission, or do you think I could fix it?

[comanchedude]

Could be couple things.. Could be throttle position sensor. Could be fuse.one in fuse box..7.5 iir or the one inline to the tranny computer behind the dash..

Check fuses first if that's good and the tranny computer is getting power,then it's most likely the tps. Of course check all connections as well. But the symptoms described usually indicate the tranny computer is offline for one of the above reasons

[Roggesound]

Thanks. That's exactly the kind of info I was looking for. If I can make the transmission work, the truck becomes much more worth it to me.

[cruiser54]

Could be couple things.. Could be throttle position sensor. Could be fuse.one in fuse box..7.5 iir or the one inline to the tranny computer behind the dash..

Check fuses first if that's good and the tranny computer is getting power,then it's most likely the tps. Of course check all connections as well. But the symptoms described usually indicate the tranny computer is offline for one of the above reasons

 

The 7.5 fuse in the box is for the Power/Comfort switch only, along with reverse lights.

 

The inline fuse up under the passenger side dash wrapped in yellow tape is the one that powers theTCU.

[64 Cheyenne]

Price go down...?

Before you attempt the fix?

Or before you tell the seller so the price don't go up?

[Eagle]

If he can shift it manually, the transmission obviously works. The problem is either the fuse for the TCU, or the TCU itself.

[88mjgilley]

yep tcu if you unplug it it will do exactly as its doing so i would say its either a loss of power or it went bad