GM Service Manual Online
For 1990-2009 cars only

Caution: Refer to Test Probe Caution in the Preface section.

The following procedure determines the frequency of a signal:

Note: Connecting the DMM to the circuit before pressing the Hz button will allow the DMM to autorange to an appropriate range.

  1. Apply power to the circuit.
  2. Set the rotary dial of the DMM to the V (AC) position.
  3. Connect the positive lead of the DMM to the circuit to be tested.
  4. Connect the negative lead of the DMM to a good ground.
  5. Press the Hz button on the DMM.
  6. The DMM will display the frequency measured.