How can I test my Speedo sensor?

[DannyBNH]

Speedometer stopped working recently. I had the engine and tranny out recently and the speedo worked fine after replacing them... then died about a week later.

I'm thinking it's the pulse sensor on the transmission for the speedo.

I've already reseated it a few times, cleaned it, and checked the connections in the box behind the seats... All seems as should be..

Is there any way I can test the sensor on the transmission before buying one to make sure it's the problem...

Thanks
Dan

[docrodg]

An analog multimeter works great as you can see the needle sweep with the pulses. You can also use an oscilloscope if you have one. I would not recommend a digital multimeter as they rarely have a fast enough response time to show the pulses accurately.

I wonder of a tach/dwell meter could be used as well? IIRC there are four trigger points per revolution so a tach meter should pick it up just like a 8-cylinder motor. Would have to check the circuit tho to be sure.