older supra rpm gauge question??

Ok I am in the process of fixing some things and my tach has not been working. My question is where does it connect on the engine?? What should i check to diagnose? Thanks

Mine doesn't work either it goes up to 1000 and that's it

Here is a PDF scan of the electrical system Wiring Diagram from my 89 Sunsport Owners Manual titled Supra the 19'Series.

Upload Supra.pdf (91.8 k)

usually off the distributor. not exactly sure how, since mine has two wires. pos and neg.

On my 406 sbc in my nova it hooks in to the distributor which is the standard GM with an ignition that replaces the stock right on the cap. The boat had the coil seperate for the ignition so I just trying to fing the right wires. My boat has been such a PITA so far this year. If its not one thing its another thing.

have you checked the guage?

Ive checked all the wires and they seem to look fine. no corrosion and are nice and tight.

Tachometers normally get their signal from the negative side of the coil. Usually boats use a grey wire for the tach signal. The tach needs to have a ground and some also need power and a lighting power source. Should be four wires max. and could be two.

That makes sense. 4 wires on the coil.