Verify Wiring and Common Ground
Not having a good ground between the gauge and sender is the most common issue. Verify your wiring is good and that the gauge and sender both have a good common ground (ground both to the same place on the chassis). The 9204 temperature sending unit does not have a ground wire connection, it grounds through the body of the sending unit. It may be necessary to run a wire from the body of the 9204 sending unit to the gauge ground location if your sender does not have a good common ground with the gauge.
Verify Ohm Signal from Sending Unit
Turn your vehicle on and let it warm up. Disconnect the gauge signal wire from the sender and check the ohms output between the sender and common ground/chassis with a multimeter. Compare the ohms output with the expected ohm output at warm temperature. Temp/Ohm data for the SCX and Comp II temperature senders can be found on the respective product pages:
If the sender is not reading as expected contact us for a replacement.
Verify Ohm Signal at the Gauge
Reconnect the gauge signal wire to your sender, disconnect the signal wire from the gauge and check the ohms between the signal wire and gauge ground wire (signal wire needs to be disconnected from the gauge). The ohm reading should be the same as you measured at the sender. If it is not, then you will need to check your wiring (use smaller gauge wire, verify common ground etc.).
Verify the Gauge
Check the SCX or Comp II temp/ohm data on the respective pages above and confirm that the gauge is reading at the expected temperature for the ohms reading at the gauge. Example: at 200 ohms, the SCX temp gauge should read approx 180F. If the gauge is not reading as expected contact us to return your gauge for checking/replacement.
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