RPM Gauge Volt Meter Test Procedure?

[treetopflyer737]

I only have one motor reading RPM's on my challenger 1800. Switched the plugs behind the gauge console and confirmed both RPM gauges do light up and read RPM when connected to my starboard motor however port motor will not catch a reading on the RPM gauge.

I Just rebuilt this Port motor- Is there a voltage meter test I can perform to see what's going on with the outgoing RPM signal of this motor? I'm assuming that the RPM gauge lead wire is in the wiring harness plug that plugs into magneto side of motor? I've unplugged and plugged all connections leading from motor to gauge without success and none of the male/female plug contacts looked corroded or burned out.

 

[Sportster-2001-951C-Stock]

In the case of marine wiring, the tachometer signal wire color is grey, maybe this info will help.

 

[ORION '95 Speedster]

http://www.ebay.com/itm/New-Hour-Me...473062?hash=item4d164aa766:g:UJQAAMXQ2kxSKprD

Installs in 2 minutes and will tell you the RPM and hours. For less than $10, how can you go wrong?