I have an mph1, 2 car group, have a problem where one car will run fine if you give it car calls, it will also answer hall calls, but will not cancel them. it has a digital pi in the car that will indicate the proper floor, however it has a regular in line pi in the lobby that will only indicate that it is at the bottom floor. Kind of a strange problem here. the coms led is illuminated on both cars, indicating a communication problem between cars, i believe. when i use my tool, the status will display that the car is not insv, even though the insv led is illuminated. I am fairly certain the mph control board is bad, but thought i would throw this out for any ideas. fcb status is ok, hfcb status is ok.

Swap boards from car to car?

idk..

It's well known that MPHI 2 car banks can have "master" car issues. Real strange about the PI at the Lobby, change that FCB? First I would switch the master to the other car, tighten conn's and reseat FCB connectors, check the close limit and see what happens. Sorry, not giving much help here.

Try turning the disconnects on in sequence?

I.e, first car #1, then car #2, or visa versa.

thanks vic i had the route guy try that with no help, good thinking though, Hey e-man, i was thinking about trying that at the job, but i could find no info on how to go about doing it. maybe i did not dig deep enough, could you explain how to make the other car the master, that would be helpful in the future. another thing that makes me believe it is the board, is that the route guy indicates that occasionally the car would only travel between the 1st and 2nd floor, it would take all car calls above the second floor, but would stop at 2 and cancel calls then it would only accept a 1st floor call. would not fault just go between 1 and 2, very strange problem. I'm hoping the board fixes it, cause I'm out of ideas generally i would try swapping the boards, but this is an 8 story hotel, with only 2 cars, just don't have the huevos to try it here,

There's an LED on the processor PCB that indicates which car is master (in the HHT also). Just turn off mainline to the current master car to force a switch. I would start looking at I/O's - HU and HD, T/B69... in other words find out when the car runs from 1 to 2 and has car calls ahead, do you have an up direction, call LED, UPSV etc. etc.
After re-reading your first post, does the COMS LED being on indicate a problem? I thought it was the COMF that is a COM failure. Unless I'm wrong because it's a car to car comm prob.

come led is fine, no problem with fcb boards. coms led indicates a problem communicating between cars. everything on the tool indicates no problem except that it won't go available and is not in service even thought the led on the board says it is. waiting for board now, they want to sell them an upgraded board. just waiting to see what they will do buy a new board or wait a week to see if the old one can be repaired.

Turns out the board was the problem, installed an upgraded board, although i did not see what the upgrade was, looked the same to me. all is well now. that was a strange call.