i have a GTA with a ls1 conversion, i want to know what is the easiest way to get the factory tach to work with the ls1 conversion. any help appreciated

 

You may want to update your title with your vehicle info so everyone knows what you are working with. There is a search feaure that is recomended to use before posting a thread, as you can usually find the anwser to most questions by using it. https://www.thirdgen.org/forums/ltx-...a-vin-h-4.html post # 172

 

You need to get the signal wire from the ls1 ecm. Take it over to the drivers side kick panel. Then pull the tach wire out of I believe the C100 connector. which will be a white wire. Now connect the 2. If it works great for you, but mine did not I had to get a 680 ohm, 1/2 watt resistor (radio shack) and spilce into a keyed 12volt source. I taped into my guage feed from fuse box. If you search it I believe Pocket has a diagram posted somewhere. Really simple though, good luck!

 

with above post.I had to do this aswell but still find that my factory tach is reading nearly 500rpm too low.I might trying playing with a few other resistors and see what gets me closer to being as accurate as my autometer tach.

Some guys get lucky and dont need the resister booster method and hook up the tach directly to the pcm,i think it matters which cluster tach is in the car between the 6cyl or 8cyl but dont quote me on that part.