Hello,
This is a follow-up to a previous post- thanks for the replies! I am now looking to understand if my issue that there is a short on one lighting circuit, but the shorts are detectable on multiple lighting circuits because they share a common ground. Any savvy folks who have encountered this?

So, I have electrical shorts appearing on many circuits, and I'm trying to figure out if it is in just one place. They show up at the underseat fuse box and the engine compartment fuse box. The fuse that blows is #20 Right Rear Park underseat fuse. Shorts show up with the detector on (underseat) 22- Frt Prk, 20 Rt Rear Prk, , 18 Lt Rear Park, 16-Upftr prk lamps.
(engine compartment) 9- Right DRL and turn, 10-Left DRL and turn ,
And also unrelated to lights, shorts in 21 and 22 engine ignition, 26 ISRV, 28 BTSI

I am guessing I have a short on one circuit, but the short is detectable on multiple circuits because they all share a ground.
I diagnosed with my new fancy ECT-3000 short finder. ECT-3000 . I have spent hours now tracking this thing using the ECT 3000 trace function.

I have disconnected both rear light wiring harnesses. I fixed a broken ground wire on the Right Rear. A fairly heave gauge wire connector had snapped on the rear right corner of the van, held by a 10mm bolt.

But, I'm stumped. Any tips for figuring out which circuit has short, when the ECT-3000 doesn't seem to be clear?

Thanks,
Rob