Hi,
Some years ago I used that GPS as it works on 5Volts (and 3.something). But when you use it with a 5Volt power supply the output signals are always 3. something Volts and not 5 Volt!!
To solve this I placed a signal amplifier between the GPS unit and the PIC (sorry, that's what I used then) to lift the signal to 5Volt. Then it works.
Hopefully this will help.
Attached the schema I used.
I am not responsible for wanted or unwanted results by using the schema in any form.
