Hi Guys.
I am installing a data logger in the truck as a test before moving it into something else, after i'm sure it does what i need.
Anyway, I need to get a tach signal to drive the RPM function.
Anyone help me ?
Thanks
Marcus

 

Tell me what year truck that you have and I will get you the wiring diagram....And I might need the engine size also....

 

It's a 2007 5.7 Hemi Quad cab.

Appreciate the help

 

PCM just realys CMP input to the tach. All digital signal until it gets into the tach itself, then converted to analog so the needle can be driven.

If your logger is designed like most aftermarket tach's (connect to coil negative, select number of cylinders), it's not gonna work.

 

Logger requires 0-14v square wave to trigger. Nothing much analog about that

 

The square waves generated by CKP or CMP are 100% analog (they are generated magnetically).

Remember, digital is on-off-on-off (or 0's and 1's, if you prefer). That's the only kind of signal digital generates. It just does it really, really fast. The sequence is what determines the information.

Anyway, if your logger is set up to read square waves, should be able totap the CKP wire.

 

CKP (crank position sensor) output, injector pulse, coil pulse, spiced into the wires. They will all work if your logger just needs the pulses, which it probably does.

I have used all of them in my SMT-6 and all work fine.

Your tach uses the ckp signal that goes to the pcm, not the tach and the pcm massages it and sends it to the tach.