Electrical pulse
I would guess you have a ground loop somewhere Either that or you have EMI from something such as the EFI/ ignition system. EG MSD igntion can cause this sort of problem
I would start by increasing ground wire size affecting the VR, AKA ground from battery to body.
Describe more about the system?
Not familiar with this VR/ harness you speak, link?
What ignition / EFI?
Where is battery located?
What do you have for grounding/ bonding from body to engine to battery?