Infectious Off-Road.com

backstory:

1989 xj aw4 trans swapped into 1987 yj with 4.2L
shift linkage for yj modified to operate aw4 shift cable
1989 xj trans wiring harness and tcu used

the trans will shift to park, reverse, neutral, 1st/2nd with the tcu connected, and using a 1989 xj trans throttle position sensor. 4.4v idle, 0v full throttle
the trans will not upshift from 1/2nd with everything connected, either automatically or manually with shifter

checked shifter position switch by ohming out 8 pin black trans connector all check ok. transmission recognizes the gear the shifter is in.

disconnected tcu main connector, drove jeep, will manually shift through all gears using shifter, including 3 and 4th gear.

my dilemma is how to make the trans shift automatically.

the trans working through the gears with tcu disconnected leads me to believe all the trans solenoids work.

my thoughts and what i will check later is that the transmission speed sensor is either not working or has a bad wire.

oh and i did get the throttle valve cable hooked up and adjusted properly as well.

for reference this swap is not on a standard 87 yj, it has a tbi(chevy s-10) engine controls so the tps from the chevy requires 0v idle and 5v full throttle. I hooked up a second tps for the trans.

sucess finally...

first thing i tested was the trans output speed sensor, i jacked up the rear of jeep and disconnected switch, rotated tires with becca's help while checking resistance on the sensor. the sensor worked.

next i ohm checked all solenoids and input/outputs on the tcu connector all checked ok.

I then wired up the throttle position sensor temporarily and with enough wire to run it by hand(thanks becca). voltage was as it should be, but trans still would not shift automatically.

I went back to the speed sensor circuit, I ohm checked with becca's assistance again from the tcu connector to the sensor pigtail, I had no continuity. next i checked from tcu to 7pin connector, has continuity. checked from 7pin to sensor, no continuity. pulled on the wires, the speed sensor signal wire was pinched/broken about 4inches behind the pin connector.

repaired the wiring for the speed sensor. test ran unit again would erratically shift, from 1-2-3, then drop into 1, then sometimes into 4th with lockup on.

then i went through a checked a few other things. couldnt find anything.

this afternoon i was putting in the front driveshaft and noticed that the night before i must of had too much in the garage. the speed sensor was still disconnected.

reconnected the speed sensor, test ran the jeep with connected and all works. shifts up and down as it should

glad that part of it is over.

Your Welcome....But i wasnt much help lol.... just good company.....

[quote="Lake_v2"]noticed that the night before i must of had too much in the garage. the speed sensor was still disconnected[/quote]

Its a good thing you noticed all the empty beer cans in the garage, otherwise it would have never got fixed. Just the sight of beer cans brings out the genius in all of us. I like to think that it was the beer that pointed you in the right direction and inspired you to think