AW4 starts in second when hot. No first.

OK, I give up.


My 91 XJ with the AW4 runs fine but was running a bit warm when working hard in the sand or in 4 low at higher speeds like 15mph. When the gauge hits around 3/4 or so, around 230* I would let it idle and it would cool down. also the transmission would stop working right after it got hot and would start out in second instead of 1st even after the engine cooled back down to 210* Waiting until the next day after it has cooled completely fixes it and it goes back to normal.


I tried swapping out the transmission solenoids and put fresh new dex/merc in. I took it on a trip and it seemed fine but then the transfer case blew up from me running it in low at high rpms. Also the water pump started leaking. I thought at least the trans issue is fixed.


Then, I put in a new thermostat, fan clutch (zj heavy duty), radiator, water pump and new hoses etc. Also a new water pump. The previous owner put an oil cooler and a trans cooler on it as well, they are in front of the condenser and radiator. the fan kicks on at about 220* or when the AC is on. Swapped out the thermostat elbow sensor with a B and M sensor, same resistance values, radiator fan kicks on at 220*


Fast forward to last Saturdays trip. It ran great all day with my son driving, then when I took over and got on it a bit the temp creeped over 210 and the transmission started acting up, starting out in second gear. The gear shift selector makes no difference, it starts out in second whether Im in D, 3 or 1/2. flooring the gas pedal, it wont shift down etc. The engine cooled back to 210 quickly but the shifting problem remained. Then the next day its back to normal until I heat it up.



So, why! Damnit.


KH

Only thing I can think of is a wiring issue. Maybe the
solenoid connector develops an open circuit when it gets
hot, and then has to cool off before contact is made
again...?

You might be able to test solenoid wire continuity with an
ohmmeter at the TCM connector, before dropping the
pan again.

I do have another TCM I can trade out and test. Its in another jeep I own.
the connectors and wires in the trans looked decent when I pulled the pan last time, I was looking at them thinking about that during the swap.
The hard part is I would have to do these tests when the problem is actively happening.
Ill have to see the TCM pinouts maybe and give it a try. Ill be at goatfest this weekend playing with it and the 4843 race buggy for KOH.

Ive had this problem years ago in a 92 and a friends 95 used to do this. Only when we used 4lo in deep snow. You are overheating the trans. Next time get out and try to touch the trand pan. I bet it will burn you.

No doubt its heat related.

I never had this problem with my 88 renix XJ and I had an atlas in that and worked it just as hard.

I wonder if I bypass the radiator and just use the trans cooler. Id want to have a temp gauge on the trans if I did that though.

KH