Ok, this is bizaare. Tach / temp guage is fine durning normal driving. Soon as I turn on flasher, hazaards, or headlights, the tach and temp guage jumps, like it pulses with the lights. Anyone have any clue as to what could be causing that? Or if there is a specific relay / ground wires / plugs that I can check. Check your grounds dont help much, cause I dont know where to start and checking grounds if i was to start from scratch might be easier to just swap the whole harness out. Was hoping for a way to avoid that. If anyone has ever noticed this happening or can suggest a place to start would greatly appreciate it. Thanks. Also, my ecu is throwing Code 17 frequently now, but have not traced down the cause of it yet. Engine runs fine. Thanks

 

might be that your alt can no longer supply the power needed for all of that... try a new 1. or 1 u know worked good.