According to the wiring diagram, the tach wire is (BLACK/YELLOW) for 2004 GS430 is not correct. If you turn the ignition to on position, the tach wired (BLACK/YELLOW) is read about 11.5VAC. The correct tach wire is supposed to read the volt only when the engine is running not on. If anyone installed the remote starter before, please help me out.
Thanks

 

I remember I had the same issue too. The wiring diagram I got online wasn't quite correct. I tried 3-4 random wires till I hit the right one by luck. I'm going to start tearing apart the inside of my car here in a bit to check out all my wiring to make sure the fire didn't damage anything. If you you still haven't found the wire then I'll report back here with my findings of which wire gives the tach signal.

 

i know on the gs300 its the first wire on the ingniter on the driverside if ur looking at the plug from the front of the car. The first wire on your right handside. I dont know if its the same for a gs4

 

JeffTsai,
I found two wires one is 12VDC and the other is the wrong wire I'm talking about. I still have no luck. Please help.
Thanks

 

Working on a remote starter install. Have any of you guys figured out which wire you used for the tach and you found it?