Bosch servodyn

Hello.
I have some old analog bosch servodyn drives that powered by a common psu rectifier.
PSU gets 3x400VAC and outputs 565VDC and all servo drives supplied by this 565VDC voltage.
This PSU has 2 ok outputs BTB1 and BTB2 that if all are ok (temperatures/voltages etc) these outputs enabled
BTB1 and BTB2 leds light and the contacts of floating relays BTB1 BTB2 closed.
The problem is that it outputs correct the 565VDC volage but the ok outputs (BTB1 BTB2) not enabled.
The PSU connects with X8 (8 pins) socket in a chain connection to the side servo drives and i suppose that X8 outputs to the side servo drives
are not correct due to electronic fault of PSU.
This X8 socket has 8 pins
FGZ (freigabe zentral/central enable) - GND - 0V - 24V fan blower - LT2 - LT2 - LT1 - PE

FGZ - GND - 0V - 24V fan blower - PE are self explanatory pins but what LT1 and LT2 pins are ? knows anyone what are these pins ?