Nissan Patrol 4x4 (Africa)

I have a 2005 3.0 diesel and am having problems with the sound from the radio. It is the original Nissan radio with single CD player. Everything works fine but no sound from speakers. If you are on a long trip and leave it playing the sound does come back. I have changed the radio and fitted a new one and the same problem persists.
Has anyone any experience with this problem?

Is there not a amp in line?

Clean the plugs at th edoors [open the door, there is a wire harnass that goes in -- twist the plaug anti clock, remopve, clean with WLECTRO KLEEN and soft tootbrush .. that car was at the coast and the contacts packed with salty air [aangepak]
check where the YELLOW wire goes -- it is for the antenna .. if you dont have an electric antennae, the yellow must be free.
MAYB previous owner had a reverse camera .. that also may effect the speaker's operation. .. but I doubt it in your case.

Thanks guys. I will check the connections.