91 GSX, RPM Signal not working

[wickedimports18]

The internal RPM guage dont work. I found the test wire under the hood in the back wall but i dont get the signal either. I bought a tachometer on ebay and tested it on a 98 and it works. Can anyone help me find another RPM source so i can plug in the tach? Also will any tach work??? And any ideas why the signal doenst work. I mean where does it get it initially?

 

[DSMsamurai666]

You can get an RPM signal from the plug on the cam angle sensor. Pin #2, black wire. There are two black wires on the plug. Its the second one from the left if you are looking at the sensor from the passenger side of the engine bay.

 

[steve]

The internal RPM guage dont work. I found the test wire under the hood in the back wall but i dont get the signal either. I bought a tachometer on ebay and tested it on a 98 and it works. Can anyone help me find another RPM source so i can plug in the tach? Also will any tach work??? And any ideas why the signal doenst work. I mean where does it get it initially?

If it's really a 91 and still has the original ignition the signal comes from the power transistor to the ECU and tach in the gauge cluster.

Many cars have been bastardized and have older style engines and parts installed because their owners were too cheap or too stupid to know the difference.

The real 91+ coil pack will have a three pin triangle connector and a 8 pin connector to the power transistor that's mounted on the side of the intake manifold below the coil pack.

The earlier coil pack will have a square four pin connector and a 7 pin power transistor. On those the tach signal is generated by a module on the coil pack and connected to the extra pin.