Good evening,
Its been awhile since I was on here. I got fed up with life and the bronco took a back seat to every other thing. Finally got back to it last week. Its been sitting up about 2 years. Many different issues to figure out. But here is the most annoying one.
When I turn my key to "On" the tach jumps right up to about 500 rpm. Once the struck starts, the tach stays around 2500-3000 rpms and does not change with engine speed. Hard reving may make it climb another 500 or so. I'm thinking a short somewhere. It will drain the battery fast. Like brand new battery will be dead after an hour. New parts include starter solenoid on the firewall, and on the starter, followed by a new starter/starter solenoid. Problem was present before and after. Meter on the battery while idling was 13-14. Could it still be the alternator? Has anyone had this issue happen to them? Other than starting at one end of the harness and working through the whole thing, any ideas?

 

I doubt the tach is the battery drain problem. put a 12v test light between the cable and post on one of the battery terminals and start pulling fuses to isolate the circuit......also the alternator + lead.....to check it for a draw