Justrob

I'm sure it's been asked a thousand times before. But I have tried the fix and nothing works. I have a 95 Silverado pickup with a 2005 lq9 swap. Running psi harness. I have the tach hooked up but it only reads half of what it should. I have hooked up a 1000 ohm resistor to a fused battery source. And a 690 ohm resistor. No change at the tach. I only have a multi meter to test with. With just pcm tach wire hooked up the tach gets about 4.5 volts and reads 250-300 rpm at idle. With the 1000 ohm resistor hooked up it gets about 6.5 volts but still reads the same. The 690 it gets about 9 volts and still no change. It moves with engine rpm just not correctly. How can I fix this? I have checked all my grounds. Hooked to the tach under the dash to bypass engine bay wiring tried different power sources. No change. It's driving me crazy. Please help.

Russ K

iTrader: (1)

Remove the resistor and set the tach output high & low fields to 3.

Russ Kemp

Justrob

I ordered a new ecm from psi since they did the tuning. Won't cost anything once they get the original one back. Thanks for the info on the tune. Can anyone explain why the resistor trick did not work. ? Now it's just a curiosity thing

Russ K

iTrader: (1)

It's because LS tachs function as a 4 cylinder tach. PSI should know this.

Russ Kemp