stock tach w/ LS engine question

Malihoochie-

Not-quite-so-new-guy
May 14, 2020
44
18
Detroit area
I looked thru various posts, but am unsure about this, what cyl setting is the factory tach supposed to be set on when hooking it to the wire from the computer? If it matters, it is a painless wiring harness being used. I saw that some say to set it in the tune, but is there a "right" way to do it initially, so it reads semi correct from the start?
 

81cutlass

Comic Book Super Hero
Feb 16, 2009
2,521
113
Western MN
Yeah there's a setting for tach output in the tune.

Do you have a stock gm pcm with hptuners?
 

Malihoochie-

Not-quite-so-new-guy
Thread starter
May 14, 2020
44
18
Detroit area
Stock gm pcm with only a bare bones tune from painless wiring that as far as I know only got rid of the vats and altered the idle a smidge....and possibly set electric fans to come on at ...🤔...185°, or something.
 

81cutlass

Comic Book Super Hero
Feb 16, 2009
2,521
113
Western MN
This is what I have on my 99-02 P01 pcm with factory harness I cut down. I think stock is 6, you need to change it to 3. The location in the tune might be different depending on the year, but thats what you need. Mine is feeding a 86 GP with the rally dash.

1589675663954.png
 

Malihoochie-

Not-quite-so-new-guy
Thread starter
May 14, 2020
44
18
Detroit area
So, with the factory rally tach in the dash, what should I have the tach (the actual, physical tach in the dash) set at?
You know, the little plug thing in the back of it. What cylinder setting should that be set on? And thank you for taking the time to answer.
 

81cutlass

Comic Book Super Hero
Feb 16, 2009
2,521
113
Western MN
Oh, yeah the 8 setting is what you want.

You could probably make it work with the 6 setting and fix it in the tune.
 

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