What type of signal is the "maintenance" tach connection on the passenger side wheel well of a 93 'Lude? Is this a PWM, a/c pulse, d/c pulse, % duty cycle?

I thought it would be a dc frequency, but my Fluke doesn't get anything. If I use ac frequency, I am getting 350-450, but engine is not idling that slowly. Dash tach shows 800.

 

my actron reads it just fine, but it has a tach setting, and also has selections for 4,6,or 8 cyl engines.

 

u need the tach adapter for ur multimeter. Some have a built in feature, some don't.

 

Hmmm - You are right - I recall that most tachs have to set the number of cylinders..... So, is this a pulse per spark?

I may have found a description - the signal should be a 12v square wave with one pulse for each cylinder per rev.

I need to try my meter again. - I think I just need to take the frequency and divide by four.