Have a '93 that I put a 5.3 into and I'm getting ready to get the A/C going, and I'm looking into getting an RPM signal from the GM computer output to the Toyota ECU. I tried the tach signal output from the GM harness to the Ne & IGf terminals on the ECU with no luck, no movement on the gauge.

The tach signal output can be changed via tuning on the GM computer, but want to see if I can just get any movement on the gauge before having it tuned so I know it will work.

Or should I tap into one of the coil wires on the engine and route it to the IGf terminal?

Thanks in advance...