Resolved 2G RPM not reading after harness swap

[DsmKhan]

I have 99 GSX, that I just did a Ohms engine harness swap and the rpm is not working.
Not sure if the rpm come from the ECU or something else need help?

 

[luv2rallye]

Tach signal comes from the ignition Power Transistor.

 

[DsmKhan]

Ok that has been related inside the car, how how does the tack at the signal from that, is a wire running to the ecu? If so what pin is it ??

 

[luv2rallye]

For 2g turbo it goes to ECU pin 58.

 

[DsmKhan]

So pin 58 from the ecu the white wire runs to the Ignition power Transistor??

 

[DSMPT]

So pin 58 from the ecu the white wire runs to the Ignition power Transistor??

Yes, the ECU pin #58 is connected to the PTU pin #4. And that white wire is also shared with the tachometer.
Not reading the RPM signal at where? At ECU or the tachometer? I assume at the tachometer. If so, just trace the white wire from the pin #58 and make sure that it also goes to the gauge. I don't know which harness you are using but if it's a race harness, you may need to connect the tach signal to the tachometer by yourself.

 

[DsmKhan]

Yes the tachometer not reading I have the ohms wire harness. So from pin 58 to the back of the gauge cluster is where I should Connect??

 

[DSMPT]

So from pin 58 to the back of the gauge cluster is where I should Connect??

Yes. From somewhere on the RPM signal wire to the gauge. Are you sure that the ECU is reading the signal?
Please refer the diagrams below. The red line is the RPM signal wire (White) between ECU and PTU that we talked above. The green line is the one that goes to the gauge cluster. Trace it and see if you have the signal there.

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[DsmKhan]

Ok I’ll work on looking for that and get back to you thanks

 

[DsmKhan]

I figured the problem out. I have a eboost2 gauge and the yellow wire I put it to pin 58, took the wire off and rpm back working always simple