Tach issue
 

HI I have an LS3 PSI harness and an auto-meter electronic tach. The tach is a special addition 2006 Gm Performance parts issue that I need to keep.
I mention this because tachs pre 2007 are known to have a problem with low voltage signals.

Tach is inoperative but is fine on a bench test. Found lots of info about using a step up resistor inline. Then found so much conflicting info.. Mus use 12v.. not must use 5V... must use 1Kohm.. no us 5K ohm. that I got really worried.

So I went out and bought autometer 5117 https://www.autometer.com/tach-adapt...E&gclsrc=aw.ds

question has used this tach adapter? Instructions say tap into each coil bank.. which I am not doing..
I want to use the tach signal (white wire) out of PSI harness

Alternatively If someone could set me straight on the step up resistor that would be helpful as well

12v 1kohm resistor. Follow this. https://lt1swap.com/lsx_tach.htm Ive done it several times.

Also make sure that the tach is set for 4 cylinder.