I am working on a 1994 F150 for someone and it has a been switched back to a carbureted V8 engine. It was originally a 300-6 truck. Has a factory tach in the dash that reads incorrectly since the wiring harness is for a 300-6, not a V8. There is a pin in the big square engine wiring harness connector under the hood that if grouned will set the tach for a V8 engine. Anyone out there with a wiring diagram that could tell me which pin in the connector needs to be grouned to switch the tach to V8 mode?

 

You just need to ground pin #10 of C250 at the cluster.


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Thanks for the info! They are bringing it to me later this week, so I will tear into it and see what I find.