Not down shifting.........its like theres no TC

91 laredo,4.0, 6 cyl, auto


ok.....ya know how yur jeep wont down shift when the tranny computer is not plugged in? (if set in 3rd or 4th....it will not start out in first, it will start in the gear you selected...)

well mine started doing that randomly.....soo some people said check the TC So i unplugged it and nothing happened....then i unplugged my brothers TC in his and now his was doing what mine was doing. so its not the TC it works fine (i switched with my brothers and it works in his). Should i suspect it is the connection or wiring between the TC and tranny? or can it be something else? and how shoudl i go about checking it all........? thanks for any info

nobody knows???

there's a fuse in the fuseblock for the TCU, mine blew before and it did this.

TPS? dirty TB? I recall someone mentioning those two items being potentially a cause of similar problem. Search around in the forum as I think that this was covered within last month or so. (check this out and search for more threads that include downshift in them )

Slip KId, what fuse exsactly because ive pulled every fuse i can find under the dash and under the hood none say tcu.....and i did not find a bad one...thanks

My 87 has a fuse right on the harness next to the TCU, trace back from the TCU connector, you will find it.

thanks guys problem is solved.. i just spent the last 2 hours cleaning every electric connection and fuse i could find under the hood and givin it some dielectric grease and its workin so far! !!!! yesssssssss


thanks for the help everyone