Voltage on trailer brake line with brakes not applied

[ridesabout]

I just purchased a new Chevy 3500 and when checking the voltage at the various prongs in the trailer plug at the rear of the truck discovered that there is a voltage reading of 3.5 to 4.6 on the trailer brake prong even though the brakes have not been applied. The Integrated Brake Controller readout shows no voltage output. Has anyone noticed this on their truck? Should there be such a reading? Any ideas?

[gijoecam]

ScottG wrote:
It has to put out just a little voltage in order to sense the presence of the resistance in the magnets.

This. The system is checking for a connection at all times to determine if there is a trailer connected or not. The voltage is usually always present with the key on, but is almost no current (a few milliamps at best, even if there was a dead short).

[ScottG]

It has to put out just a little voltage in order to sense the presence of the resistance in the magnets.

[Learjet]

voltage but no amps, put a load on it and it will go down I bet.

[WyoTraveler]

Yes normal. Have someone apply brakes and voltage will go up. There is a votage to show when TT connected.