Review on ACDelco 20904439 Original Equipment Continue by Jairo Cunha

I'm very glad it worked. This stupid service trailer braking system has been bugging me for months, although the trailer lights and brakes still work fine, it chimed every time I started the truck. I had no idea where to look for the problem. People talk about measuring voltages, checking this and that, blah blah blah. Someone else says swap the little relay for $15 and like magic it will fix itself. For the record, the relay looked fine, no idea why it wasn't working. The exchange took only 15 minutes. I am grateful that people understand this and publish it on the internet. I'm sure the dealer would say just swap everything out bumper to bumper for a few thousand dollars and you'll be fine. May be. FYI, that was for Silverado 2007.5.