I have wired up a couple of these to work perfectly. There was another thread where it was covered but I never went over the wiring. I am not going to tell you exactly what wires go where, but I will point you in the right direction. Use the 2 plugs that go into the cluster and the 2 plugs that go into the USDM harness behind the dash. Now download the 1991-1993 S13 240SX FSM and look at the electronics section and the meter wiring. You will notice that the gauge cluster has its own wiring diagram printed on its circuitry. Start soldering the wires that need to go together.
You will also need to put in an S14 speed sensor and S14 temp sensor (single wire sensor) for the cluster to read these guages right. And open up the cluster and put some electrical tape over the AIRBAG light, otherwise it will never turn off.
Here was the old thread:
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