Power Level Jumps Up with No Trailer Connected to a 2004 GMC Sierra and Primus Brake Controller

Question:

I just installed a new Primus IQ in my 2004 GMC Sierra 2500Hd 6.6 ltr turbo diesel. When I unlock my truck and even while driving sometimes it shows a fluctuating power setting of 0.5 up to about 2.7. No trailer attached. It does go away eventually and displays the . . as it should with nothing attached. I did not read anything in the installation guide / troubleshooting chart about this. The brake seems to be working fine when hooked up to my RV, so Im not really worried about it to much. Just would like to know if you think there is a problem.

asked by: James F

Expert Reply:

The most likely cause of the power jumping up on the brake controller with no trailer connected is a dirty or corroded vehicle side trailer connector. Check the connector on the truck and make sure it is clean and free of corrosion inside, where the wires attach, and outside on the pins.

What can happen is corrosion will cause electricity to jump from a nearby pin to the brake pin drawing power and causing the brake controller to display output voltage.

expert reply by: Michael H