With sensitive aftermarket audio equipment, unused energy from solenoid valve coils can be transmitted through speakers as a pop sound. Here is the suggested resolution from audio specialists: To eliminate speaker pop, wire any #4001 through #4007 diode between the positive and negative wire of each solenoid valve coil, with the cathode side of the diode connected to the positive side. See attached photo for reference, and list below of valve/relay wire colors for our systems:
Front UP valve - Green(+), Black(-)
Front DUMP valve - White(+), Black(-)
Rear UP valve - Orange(+), Black(-)
Rear DUMP valve - Red(+), Black(-)
Compressor Relay - Yellow or white(+), Black(-)
