I have an old school TAC50. Basically it's a T4 in TAC50 clothes. It will not allow the hall calls to pick. Here are the some specifics. This unit was running until it went down with an encoder fault. The encoder was changed by another mechanic. After this is when I got involved. I have my HCP input on the group. The car shows in auto on motion diag screen. Group controller is showing fire service along with a group fault 11. I am not picking my AHC relay along with my AHC output. Group fault 11 states there is an EEPROM load error. It said to do a group parameter initialization which I did. Hope this isn't all over the place. Trying to get it out while its all on my head! Thanks for any help!

I assume you have tried to reset from the key switch and made sure fire service inputs are correct? Does the 11 fault return if you clear it? You might try a GET command.

Yes. Reset has been tried. Inputs appear correct. 11 never goes away. GET command returned an OK

Peak,
Did you try Fire Recall Phase 1? Did the doors open? Both key switches returned to "Off" positions?
Will the unit take and answer car calls?
This is a simplex yes? If it's an early TAC50, the PMI boards are laid out similar to a late Dover Traction I believe. On the board that has the fire stuff, check those wire termination header plugs for good wire connection and that the plugs are seated fully, then try to reload the job. Module locations should be on the inside controller door and they are on the print, and prints are job specific.
Bad FE module? (I forget what acronym they give fire stuff, I know it's not FE, (FSM?) but whatever main floor recall is).
Sure seems odd that this seemed to "just" happen out of nowhere.

If the inputs are correct inIMS then the PMI modules and wiring are fine. Make sure there isn't an auxiliary fire service switch somewhere. Have you tried reseating the EEPROMs and the CPU card? Sounding like a software problem, might be worth replacing the CPU but may need to buy software from TK if not archived.

I had one that thought it was on emergency power and it was a lose connection on the PMI board where the input output module was located. Also had a bad door zone and had to change the input module. Like elmcannic is saying check for the location on the door.

I'm suspicious that all input/outputs would be correct as part of his trouble is the failure to successfully load the group parameters, and two different modes of operation. But that's just me.
Hopefully he'll come back soon with the resolution.

Ya, I guess the question is whether the Inputs and outputs are correct. Can you pull up the group I/Os on an older TAC50 to make sure they match the car like a TAC 20, 50-03, 50-04? I don't remember.