GMPP Drive by wire ECM to factory tach?

[formula]

So, I'm about to look like an idiot--but is there any way at all to connect the ecm on my l76 to a factory 2nd gen tach? Or does anyone have any info on how it'd work at all?

All I've heard is that the ls engines put a signal out like a 4 cylinder and confuse the tach--but is there any way to get in and change the output frequency value in the tune, or something?

[neki67]

They idd do put out a 4 cyl signal. You could try changing the hi/lo time for the tacho output. G1202/3 table. This is not available in the GMPP calibration, but you can load e.g. a CTS-V calibration. You than change the hi/lo from 15/15 to 8/7. This doubles the number of tacho pulses from 2 per rev to 4 per rev. Obviously you need EFI-live or HP tuners to do that.

You also need to wire in a 5K pull up resistor, the instruction that come with the wiring harness have changed and includes the following picture that tells you how to wire it.

https://static1.pt-content.com/images/pt/2009/10/tachsignal-1.jpg

[formula]

:1st: you win the prize, sir!! Sounds like I need to call frank and figure out what my current tune is before I delve any deeper. I've been considering investing in either hptuners or efilive anyway, and the only other solution I've found to convert the signal is about 90 bucks from dakota digital:

http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=127/category_id=105/home_id=59/mode=prod/prd127.htm

Provided that would even work.

[TnBlkC230WZ]

Are these instructions also correct for an Autometer tach? Can I set my tach to 4 cyl and ok? Does Autometer have an adapter that I need?

[dhutton]

:1st: you win the prize, sir!! Sounds like I need to call frank and figure out what my current tune is before I delve any deeper. I've been considering investing in either hptuners or efilive anyway, and the only other solution I've found to convert the signal is about 90 bucks from dakota digital:

http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=127/category_id=105/home
_id=59/mode=prod/prd127.htm

Provided that would even work.

I used the Dakota Digital converter with my LS1 and factory tach and it works well.

[garys 68]

Most aftermarket tachs have a setting for 4,6, or 8 cylinders. Just set it at 4. And you may, or may not need the pull up resistor. Try without it first.

Are these instructions also correct for an Autometer tach? Can I set my tach to 4 cyl and ok? Does Autometer have an adapter that I need?