omega_rugal

i like that attitude, nice to know someone who knows to handle electronics too

weird, a TCU that dies all of a sudden... try with a known working one before buying, also read this https://www.naxja.org/forum/showthread.php?t=1053970

is it getting 12v? is it properly grounded?

the transmission is not shifting, let me guess, if you start in 1-2 and go throu D and OD manually it drives ok?

some say 20w-50 motor oil works fine, no need to use expensive oils on a tranny that can die at anytime last time i changed the oil on the old 4.0 i used 20w-50, a quarter of 10w-40 for Diesel engines for the zinc content and a small can of engine restore... btw it still looks bright and clean as coolant for the past 6 months or so i have been using the water that drips from my AC, it´s not distilled water but is not tap water either, so far no signs of rust. in winter i ll add some antifreeze if temps go low, it gets cold here but never SOO cold for the coolant to freeze.

the steering box is a little loose due wear... check this video WARNING mark the starting point with liquid eraser, do it in small steps, 10 degrees of a turn, do a test drive, a few more and test, the bolt must never get tight, this is a common mistake most people make, if the bolt refuses to turn, stop and turn it back. if after an adjustment the steering wheel feels stiff it means you went too far, loose it a few degrees. steering boxes wear down overtime and this fix must be done a few times during its life span, if you go beyond 45 degrees and nothing improves then the box must be replaced or rebuilt

not worth going hunting for an OEM unit... the 3rd brake light isnt a requirement these days?

the elusive bed light... does it had to be ordered or came with a specific trim?

unless you know how to dissasebly a steering column and remove all the stuff you don't need/bypass the right cables, i suggest you to gen a manual column and swap it theres no easy fix for your problem

if it s both you may have low coolant or a pressure leak, higher pressure raises coolant boiling point, if the coolant can not build pressure it overheats other causes could be a stuck thermostat, running too lean, too much spark advance, crowded engine bay the worst would be a blown head gasket it grinds my gears that whenever a car overheats people keep changing thermostats...

a confirmed working TCU does the same? then you have a bad wire somewhere if it comes from the same year XJ/MJ then it should be plug n play, there are like 3 version that are not fully compatible, 88 - 95, mid 90s ones and 99+ ones that would be the right procedure but you need a tester with some long cables since you already confirmed that the tranny does shift when the solenoids get power why don't you install a 2nd gear switch? or better yet, a manual shifter?

try before buy, it may be a bad harness too

25. Valve cover mod Most early and even later Renix 4.0s could be bothered by excessive oil in the air cleaner box. A fix from my old days as Service Manager at a Jeep dealership follows. Information was provided to me from a buddy at JeepTech during those days. I don’t believe it ever came out in a Technical Service Bulletin. Remove the valve cover and turn it over. Next, remove the fluted tubes that are now facing you by removing three screws on each. Chop 1 inch off each of them. Then, about a half inch up from the area where you just sawed them off, drill a half inch hole in the tubes so the holes will face the rear of the valve cover. Clean and de-burr/sand all rough edges nicely, clean with solvent, and reinstall. Don’t be concerned about the chintzy gaskets that will probably crumble into oblivion when you remove the fluted tubes. They can go back together without gaskets. _____________________________________________________________________________________

try cruiser´s tips, cut the flutes in half and drill a hole in the inner side, it will suck less oil vapours

then the TCU is dead...