Tach wiring for 99+ Vortec/LS

Some PCM tach signals are too weak for some aftermarket tachometers. Connect a 1k Ω (brown/black/red) resistor between the tach wire and a fused key-on 12V source: one end to the tach wire, the other to fused 12V+. The tach wire is Pin 10 on the RED PCM connector for 1999–2002 vehicles and Pin 10 on the GREEN PCM connector for 2003–2006 vehicles.

Diagram of an automotive electronic setup with a 12-volt fuse, 1K ohm resistor, a gauge, and a connector wire connected to a customized car-themed decal featuring a lion, various car brand logos, and the text 'Ewalts Auto Tuning Unleash The Beast'.