Hey Jeff (or anybody else with electronic knowledge)!
The manual also says to use "J-33431 I/P Tester" (Which I don't own) to test the Tach signal. It says to disconnect the connector to the Computer Controlled Coil Ignition (CCCI) Module and use the black lead of the J-33431-10 harness adapter to ground and use the red lead to the CCCI at terminal "E" (WHT). You then set the tester to "54 MPH", "60 MHZ" & turn power switch on. Turn the ignition switch to "RUN" & if Tach shows 1350 RPM, replace the CCCI Module or if the Tach doesn't operate, check WHT (121) wire for a open or short to ground. If OK, check that all I/P Cluster connections are clean & tight. If OK, replace I/P Cluster. Since I don't own this "J-Tool" I thought I would just see if there is a signal going to the Cluster instead!
I found the Tach signal pin location!
It'* "B15" WHT (121)!
Will this idea of mine work?
Have you ever torn apart your Cluster yet? I have, to fix the odemeter setting. The reason behind all this is that the Tach cuts out from time to time for no reason & the RH Turn Signal Indicator in the Cluster only doesn't work (but it does "click")!