Have a TAC 20. 2 stop, twin post single stage jacks,4500 lbs capacity, 2 sp side opening doors, LD-03 door operator. No emergency lowering UPS. It has a pressure switch. Does not have a UIT and we do not have access to IMS.

Issue: Every morning we find the car in the pit. It has all run LEDs high and electronic starter ready to go. Will not level up or take a hall call. Upon reset it levels up and runs fine all day.
We replaced all 24VDC Finder relays,verified selector,tape and magnets all OK.
Any ideas on what else to check???

jack resync. check the side to side movement of the car sometimes when the car goes to resync the jacks it can clip the hall door locks. the other thing is when the oil gets cold the up levelling pilot might work properly. there Is a filter under the up valve that may be dirty. if you take the center bolt out then the up pilot bolt the filter is inbetween. its very small. make sure to relive pressure from the valve before you pull the pilot off. very easy find if you have ims but a lot more difficult without the fault codes.

I agree with everything pdq just said. But if its a single stage jack then Jack Resync should not be enabled. If it is, you would need IMS to disable.

If you put a gauge on it, turn off the disconnect and close the hydraulic supply line. You will lose pressure if there is a problem with the valve.

In my experience, it sounds like you have tripped the run timer after a re-level instruction. Then it sounds like you're by passing in the block. Cold oil is harder to push thru the block as it is thicker. I would also make sure your re level limit or magnet isn't real close to true floor level as it then cant have a good action the come back to floor level. You cant test this by opening the manual lowering valves. I would check the block as JKH said to make sure you haven't got a bad o ring or gauze.

Thanks for all the great comments:
We will check all as the unit is currently in the pit.
Here are a few more details:

As soon as we reset when in the pit it levels up with cold and runs fine all day.
When we open the manual lowering it re-levels just fine with cold oil.

We will post our findings as we complete in the next few days.

Sounds like an typical LOO reset. Maybe check the screen on the up level adjuster.

Low oil timer. As car runs all day, oil loses some of its push as it gets warm. Without IMS or a UIT, I think you are stuck with making the valves very very soft. Means with cold oil you will push past floor sometimes as the oil is thick. Better call a TKE Buddy that owes you a favor as soon as you can. He should be able to verify if this is the issue within 2 minutes.

Hmmm
Got me thinking...cold oil on a TAC 20? Someone has disabled viscosity?

Not all TAC 20 or 32s come with viscosity. Was an owners option and was value engineered out a lot from 2007-2010. Would explain why car is in the pit as well, low oil timer clips when oil is warm/hot, levels to bottom floor, and shuts down. As oil cools, car slightly lowers on the colder oil. When you reset, the elevator thinks all is good, and the now colder oil works great with current valve setup.

You need ims. Period

"We will post our findings as we complete in the next few days"
OK...whu'd you find?

Ims will save your life over and over, check the up leveler adjuster on the valve

Speaking of viscosity, make sure the car is not creeping up while running the pump to heat the oil up, leveling back down, up, down etc. This will shut the car down. If so, reset bypass.