Hello Steve ,

i have some erratic values on BTN result ( BTN = TRISB ) under pic smulator ide 6.91 .
like 1 . 2 . 4 .255 and cycle infinite .

But i will try this evening on led test or resistors.

I note in 16f877x datasheet that with "1" TRISB , we have High Impedance so we can choose whose resistor to be put off .
But with other state bit of TRISB , i don't understand how tie to common +5V of car radio (TIP) to the RB0,RB1,RBx..... ???
We have agree that it is a result of a resistor between common ground (sleeve) and +5V (tip) on jack "grip" .

Hervé.