Air Brake Gauge Malfunctioning

[Lou Placentia]

My air brake gauge is jumping up and down, Any ideas what would cause this??????

[Will Procter]

Electrical problems, often a bad ground for the dash instruments, is often the cause.

Will

[77newell]

Is the gauge electrical with a remote sensor or mechanical? I suspect it's the former based upon the symptoms. If this gauge operates the way the rest of my panel gauges then the ground will be located at the sensor. There are two other possibilities; that the gauge itself has an internal random short (this can be tested by removing any ground connection from the case of the gauge), or even less likely that the voltage to the gauge is fluctuating.