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've double checked my connections, I'm using the white wire on pin 10 on the pcm.

I do have a blue and gray wire off the tach that are not connected. And there is not a 4cly switch or any other wires to cut on the tach.

Any suggestions? Thanks!!

CoolAid

Stock tachs in 4th Gen Fs are commonly off. Mine reads 150 RPM lower than what HP Tuners and Torque show from the PCM.

I remember tuning the A4 trans in a 2000 Z28 and yelling at the driver to SHIFT! SHIFT! as we crested 7,200 RPM on HP Tuners. We were holding gears to 7,000 and when HPT was reading 7200 he was at 6800 or 6900 on the stock tach.



Check your new one against a PCM scan, not the stock garbage gauges.

TXCatfish

Wow didn't realize the stocks were off that much. Mine at an idle shows .500 on the autometer but I know it is higher then than.

I did find the instructions for this model tach. The wiring is correct but it has an option in the settings for 4,6, and 8cyl under "pluse per revolution" settings. I'm going to give that a shot and if it doesn't work I'll try a pcm scanner.

Thanks!