Mega 2560 analog read trouble

I have an issue I’m not sure how to solve.

When I attempt to perform an analogRead on pins A0 - A15 they give a strange result.

When displaying the read value when trying to read a 5V signal pin A15 gives a value of 69.
A14 gives 68
A13 gives 67
A12 gives 66
A11 gives 65
A10 gives 64
A9 gives 63
A8 gives 62
A7 gives 61
A6 gives 60
A5 gives 59
A4 gives 58
A3 gives 57
A2 gives 56
A1 gives 55
A0 gives 54

The above values do not change if I turn the potentiometer. I have swapped in a different one to test that. with no change. Even tried reading the voltage directly from the +5v pin to the readpin.

If I attach a 330 ohm resistor to a LED it will light so I know there is voltage. I placed a 10Kpot on it and I can dim&brighten the LED as you would expect.

I’m at work now and can post the code later this evening.

int voltReadPin=A0;
int readVal;

int delayMs=5;

void setup() {
// put your setup code here, to run once:


void loop() {
// put your main code here, to run repeatedly:





Any insight is greatly appreciated