bad ground... or something else?

[BLACK&chrome]

My 99 k2500 ccsb is having some electrical problems. . Hooked up the dual batteries and now my left blinker doesn't work with lights on but does with them off.. when I hit the brakes with lights off my dash and parking lights turn on..

I'm thinking bad/missing ground as I found the 3/4 inch strap broken I think it goes to frame or engine not really sure.. anyone know where or what length it is supposed to be

 

[98_k1500]

Does sound ground related. Check the one at the rear of the truck on the drivers side. There should be a strap between the passenger head, the firewall, and the frame rail also.

 

[BLACK&chrome]

The one that's broken I found laying on drivers side arm.. was hooked up to the same spot as drivers side batteries negative post.. however I can't find the other end of strap.. anyone else have a factory dual battery set up that can locate the position of the 3/4 inch strap and figure out correct length.. the problem didn't occur till I hooked up second battery so I'm assuming it's caused from that ground strap not being hooked up since it is broken.. I have a picture of the strap and where it was bolted but it won't let me upload from phone for some reason