So I've got a '96 VQ30DE in my '73 240z. The engine, wiring harness, and ECU came out of an i30 with an auto trans. I've got the car running and driving after spending a year doing the swap and one of the things on my list of "not working as planned" is the tachometer. The wiring harness has been stripped down to the essentials (removed EGR, EVAP, etc.) and I'm using pin #5 on the ECU as a tach signal source. I know my tach (made by autogage) works because it worked with the stock engine and I haven't changed any of the tach wiring except for the signal wire. Anyways the tach does not react to the engine starting, running, or revving, it just stays at 0 rpm. I read that you can test the signal by reading AC voltage between the tach signal wire with the engine running and a ground and when I do that I get 0 volts no matter how much I rev the engine. So at this point I'm fairly confident that I don't have a tach signal coming out of the ECU, any reason why this would be? I have both crank angle sensors wired in, the proper flywheel timing ring, and an engine that runs great and seems to have no spark issues etc. Unfortunately, I don't have an OBD2 port to read codes from currently but are there any codes that would stop the ECU from sending a tach signal? I'd appreciate any advice, thanks!

 

The other gauges working? Are all of your power and grounds hooked up? I wired in an i35 cluster for my 3.5 swap and theres illumination wiring from the light adjustment switch plus there's a couple power wires I don't think my tach worked without the power hooked up

 

Sorry if I didn't make this clear but I'm not using a gauge cluster, I'm using aftermarket gauges.

 

The more you change your car from what it was to what it will be, the harder it is for most of us to help you.

 

Just because it worked with your stock signal doesn't mean it works with the signal provided by your new engine. Different engines different sensors, very likely different signals. If your car is running good then you're getting a good tach signal. Your gauge is either not compatible or it's your gauge wiring

 

The dash tach signal is definitely from the flywheel/flexplate CPS. I'm not sure what pin that equates to but that's the one you should use.