1995 Camry TDS

[Nordnog]

My keyless entry (TDS) system on my 1995 Camry works intermittently. One day it works, the next it won't, or sometimes in the same day. I changed the batteries in the fob. The fob looks like it's working, the led lights strongly each time pressed, but the doors won't lock or unlock, and the system won't arm/disarm.

I suspect a loose connection in the transponder or ECU whatever it is called. Where can I find this device?

Thanks for your advice.
Keith

Also, where are the manuals in this website. I can't find them.