New tach

[silverbullet]

I just got a new 5" tach w/shiftlight, for my 04 silverado 5.3. An I was just wondering how to wire it in on these NBS trucks. I know where the red, black an white wire go, but what do I connect the green wire to, so that it can read my RPMs? I know some of you guys out there have a separate tach, so if you could drop me some info. Thanks

[silverbullet]

I just got a new 5" tach w/shiftlight, for my 04 silverado 5.3. An I was just wondering how to wire it in on these NBS trucks. I know where the red, black an white wire go, but what do I connect the green wire to, so that it can read my RPMs? I know some of you guys out there have a separate tach, so if you could drop me some info. Thanks [/b]

Come on, I know there are a few guys out there with aftermarket tachs right, so someone please help me with wireing mine up.

[RedHeartbeat]

I hope you bought the right model. LS1 PCMs only put out 1 or 2 tach pulses per revolution. You may have to set it up as a four cylinder tach for it to work correctly. My 92 six cylinder tach expects 3 pulses per rev for the factory tach and it reads way low when hooked directly to the LS1 tach output signal. If you bought a conventional style tach you will be best off to try it set up as a four cylinder module unless it was specifically designed for the square wave tach signal of a late model GM V8. The wire it will hook to in the PCM should be pin 10 on the red connector, white wire for a 2001 harness. I am not 100% sure of the wiring configuration on the 2004 since I won't spend $100 on a manual for a vehicle I don't own.

[silverbullet]

Do you think its posible to cut/cross into the wiring that is already running to the factory tach? I thout that might be a simple way to do it. An the tach that I have you can change it to run on a 4 to 8 cylinder vehicle.

[RedHeartbeat]

That is what you are going to have to tap into, be it near the tach or near the PCM. I wouldn't wire it in permanent until you see that it is reading correctly. I think it will be about 1/2 of what it should be though. Just my opinion.

[silverbullet]

Thanks im going to try that. Anone else know from experiance?