See here the solutions to a variety of different faults that can occur for a Digivoice decoder 1038/34/35 or 1138/31.
Fault:
When pressing the programming key the led does not light up.
Solution:
Measure the voltage between terminals “+V” and “0V” of decoder box, if the voltage is lower than +16Vdc, then find the reason of voltage drop or short-circuit.
Fault:
The programming led flashes continuously.
Solution:
Measure the voltage between terminals “D” and “0V”, if the voltage is lower than +13,5Vdc, find the reason of voltage drop or short-circuit.