Only one car does it?
If so, quite possible the call is being cancelled due to the car being “at floor”, but the (MAC 104) door open pilot relay(s) is bad, or the opening slow speed doesn’t have the poop to open the door. If the NUD relay appears unmolested, You can swap the DO pilot with NUD on the door board and see if your issue continues (if you have enough new relays, replace them).Tight belt or bad belt(s) will give door troubles too. Also check the operator sheaves for proper alignment one to another. I’ve seen the set screws loosen and sheaves walk out or in causing door troubles.

Does this car have the IPD system? If it does hall calls can be locked out. Check IPD_Front_HX, per floor. True locks that floor, false not locked. There is also a rear IPD

Only one car does it. So I don’t think I describe it very well. So if elevator 3 is at 3rd floor and I hit down call. The call will latch but the elevator will not open the doors. However if the elevator goes to another floor it will then come back to take the hall call.

Now separately elevator 3 and 4 both have the output board. I swapped them and it went away for a few days but it’s back now. But on elevator 4 the output light stays on until the call is answered but elevator 3 output light just flashes on then goes off.

To make this even better it’s the miprom is an overlay combined with a Dover relay logic. This is on a dc traction elevator

So not exactly a 2 car group, and not quite a Miprom 21. So an at floor hall call should make DO10 output go high. DO17 the door closed limit input should be Hi, and the also DO3 input, when sitting with the doors closed. Is the operator a MAC 104 board? Is there some kind of door zone relay left from Dover? If there is a common panel on this? If so, there is are inputs called UP and DN to pilot an at floor door open. Good Luck.

Wow that is interesting. So does each car have an overlay with M21 CPU, PIO, SIO? Or is it just an M21 CPU and PIO running the group? That might be a have to be there to figure it out kind of problem. I’ve never really understood the logic of doing an overlay.

The one I worked on had the CPU and PIO laying horizontally, and a card rack with input and output boards. The only reason for an overlay, is because that was the cheapest way to get fire service.

Well, I’m out on this one!

Good luck Bricker...you get all the good ones!

Each car has the miprom overlay and they both have the cpu, pio and sio boards vertically. It has the card rack in a separate controller underneath

I believe what you have is called a "Lonnie" overlay. Was not supposed to be permanent. Was to allow all cars to talk to the Miprom Group when modded. Not sure how much info I have on it, but we used it on an Otis A Base before a Mod. I do remember the communication wires were very different then thought and very touchy units. I am pretty sure if it is a Lonnie that you can talk to it with a real svc tool using the Lon on the tool.

Do these have CSV1 and CSV2 toggling on and off? like a master/slave setup? another thought, if the output stays hi, only as long as the input, it may be out of service for one reason or another. you need to look the I O's over and see if this is the case. Make sure binary counting and such are correct. Is the an HCN input. this cancels hall calls, and is used with the PB1 PB2 PB3 PB4 binary car position. Check closely one may be incorrect and the car would think it is on another floor.

I think you need a svc tool to set up that will do lon. Not sure if world tool does lon setup.

I seem to remember an IPD computer on the job we could do a lot with too. It was connected to group.

A level 4 tool will work for m21 lon.

A level 4 tool will work for m21 lon. But id check all output boards in that rack. Could be a diff board causing that output to not come up. Does it blink high for a split second on your tool? Like 3u/3d input is high, but do10 output won't open door? What if you give it a 3c at that time? Go to motion tab i think then IOs. Watch DO10 there.

I have a customer describing what seems to be the same problem. Mine is a 96 vintage digital dc four-plex. Haven't been able to see it happen yet. I think its a hall call input board issue, 2 of my four have the hall call inputs. I've sat on this bitch for 4 hours last week, 2 different days and of course it didn't happen.