TXCatfish

I swapping out my digital rpm shift light with an Autometer playback tach. I've pretty much cut the wires to the shift light, matched the colors to the tach and connected them. Everything turned on the Autometer tach shows roughly .500 and stock tach shows roughly 1,100 rpm.

I do have a blue and gray wire off the tach that are not connected.

Any suggestions? Thanks!!

TXCatfish

Anyone? 121 views and not 1 response?

TXCatfish

I just checked my connections and everything looks good. Green wire connected to the white wire #10, I have power to the tach but the rpms are lower then the factory tach. I do have a blue and gray wire off the tach that's not connected.

LSX Power Tuning

iTrader: (4)

You need to hook it up like the directions say for a 4 cyl and it will read correct.

TXCatfish

I just found the instructions for this model tach. The wiring is correct but it has an option in the setting for 4,6, and 8cyl.

imma_stocker

iTrader: (19)

same problem here tapping rpm signal off PCM, currently set it to 6 cyl for most accurate reading. Always reads 500rpm lower than PCM from idle up.

Someone told me to tap rpm signal off a coil pack instead but haven't looked into it.

Grip

Do a search for LS tach pull up resistor.

imma_stocker

iTrader: (19)

Like so?
http://www.autometer.com/resources/index/faq_view/id/77

10k resistor connecting signal and power wires behind the tach, correct?
Link says " I recommend starting with a 10K-1/2 watt resistor, though you may go as low as 5K- ½ watt" so how do you tell which one to use other than solder, test, clip, solder, test, clip.... I expect a butchered harness in an area without room to butcher.

What can be done with a multimeter to get as close as possible for the first test?