[Macs_Chevy_S10]

Hi folks & Tech Exchange editor. I just bought a 2003 Chevy S10 Ext Cab 4.3l v6 Fleetside with 89k on it. I bought it to haul a small travel trailer (1000 lbs dry weight). Looking around underneath the rear end to check hitch & wiring options and saw the following. Wondering what two items are - first the wire with the blue cap/cover (to the left), also the round, black box mounted to frame (to the right). (In the middle is the rod that is turned to raise/lower the spare.) Appreciate any help.

 

[oldeerslayer]

The junction block with the blue cap is where all the ground wires for the back of the truck meet and then go to one bolt into the frame. Make sure that wire is healthy and the ground is clean and secure. On your truck that doesn't appear to be an issue. Pretty clean under there.
The black box with the round top and 3 wires is not OEM and could be anything. My first guess would be a back up alarm wired to the backup lights. Do it beep when backing up like heavy equipment does?

 

[Macs_Chevy_S10]

Thanks Deerslayer. So, can I use the junction block to ground the trailer wiring harness? As for the black box, I kinda suspected it might be a backup alarm, but wasn't sure if there was another OEM part. Again, thanks!