Yes, I have one. Do I connect to ground and touch the lead to the back probed orange wire and look for a pulsating light at operating temp? Will I be able to see it at the frequency demonstrated on your scope?

 

The DME is sending system voltage to the thermostat on the orange wire; it then completes the circuit by providing the ground via the white wire; when that happens, the circuit voltage drops to zero; When the DME disconnects the ground, to voltage goes back up to system voltage; in the previous lab scope picture, the scope was set to 50 milliseconds; so if you connected a test light to the positive battery terminal and then touched the tip to the back-probed white wire, the light should illuminate when the DME completes the ground circuit, but the pulses are so fast you will only see a steady light and only after the engine has reached operating temperature. Any good indy shop should have a lab scope and could tell you if the DME is switching the ground on and off; you've already verified it's sending out the power.

 

I wonder whether a multimeter set to read frequency would be able detect the duty cycle frequency.

 

Could you recommend a scope that is reasonably priced for the diyer? As you can see, electrical is the weakest of my auto based skills

 

It can't. Not fast enough.

 

 

Update? Problem fixed?