So, to start.

I rebuilt the head after driving for one week, and this started happening.

Cluster lights pulse, AC cluster flashes, and truck lopes are sequenced with the pulse.

When I use the window switches, it speeds up and intensifies the pulses.

So, the passenger battery was removed simply because the truck was just a race truck.

1st new battery stamped 2/23, same result.

2nd new battery stamped 4/23, same result.

Both batteries were sitting on a charger fully charged, good batteries.

They replaced terminals with fresh ones to ensure no cracking in the lead.

0 gauge true copper cable from alternator to battery.

0 gauge to TIPM.

0 gauge to chassis.

Brand new Mechman 240amp alternator, same result.

Is there a way to test the ecm without sending it out?

No codes, nothing.

I am using a pretty nice Launch Scan tool.