How do I test for a good tach signal?
If this is the case, rev the motor up and down and observe the reading on the meter. The AC voltage should rise when the engine RPM’s rise and fall when the engine RPM’s fall. Locate a tach source that has at least 3V AC at or slightly about idle speed.
Do you need AC voltage for a tachometer?
Note that a typical tachometer signal is not true AC voltage but pulsed, DC voltage. A Digital Multi Meter is not fast enough to read the pulsed DC voltage and this is why you need to use the AC voltage setting.
Can a multi meter be used to test a tachometer?
To properly test a tachometer wire in a vehicle will require a Digital Multi Meter capable of measuring AC voltage. Note that a typical tachometer signal is not true AC voltage but pulsed, DC voltage.
Where does the 6.5 gets it’s tach signal?
AFAIK, the tachometer is driven off the alternator on all models. This is something I have always wondered why GM did. They have a very accurate engine speed signal for the PCM, yet drive the tach from the alternator. Why would they do this?
How does a 6.5 diesel tach read the stator pulse?
And also they are specifically made to read the stator pulse that the alternator produces. The 6.5 diesel tach is run off of the stator output terminal in the voltage regulator. It simply reads the stator pulses like it would those of an ignition charge pulse since they are both similiar in wave length.
Can you read RPMs while cranking a car?
As you might already know, such a code (or codes) can give you an idea of what is going on and/or where to start the diagnostic process. OK, even if you tried using a scan tool, most makes and models will not let you have access to the Live Data (to read the RPM’s) that the scan tool provides while you’re cranking the car or truck.
https://www.youtube.com/watch?v=6l0JAwLKU14