Appearing the noise by adding the second sensor

[Idahowalker]

@hashemshah

The output of the mag is OK till the GPS module is not connected to the Arduino. But when I connect the GPS module to the Arduino the data of mag become very noisy.

Making sure I got this correctly.

Wired to a Uno is a mag sensor. When the Uno is powered on with the mag sensor the thing works. Now still powered on a GPS is connected to the Uno and then things go wonky?