Why does my PP III make a crackling sound

through the speaker as I connect it to my circuit?

What you are hearing is the probe tip puncturing through the corrosion or oxidation layer as you are connecting it to your circuit. You can simulate this by dragging the probe tip across the positive of a battery terminal (Turn the speaker tone off for a better effect) Take notice that while you hear the crackling from the speaker you will also see a “P” Icon in the lower left hand portion of the LCD. What is going on here is Mode 1 not only has the ability to display DC voltages but also AC voltages. What makes this function unique is that you as a user can set the threshold level (Mode 5) at which the display will switch from displaying DC to AC voltages. Not only do you get the reading of the Peak to Peak AC voltage but you actually get to hear that AC voltage.

This audible feature enables you to:

• Hear bad connections due to oxidation or corrosion and also allows you to listen for poor

  connections as you wiggle wires.

• Quickly find malfunctions due to high ripple from bad diodes in the alternator. (You actually

  hear the alternator whine as you rev the engine)

• Verify and trace various audio sources from Stereo Pre- Amps and Power Amps.

• Listen to logic circuits from the Engine Control Unit (ECU, ECM) for activity.

The voltage threshold level setting can be manually adjusted to

7 different levels:  0.2v, 0.5v, 1v, 2v, 5v, 10v, and 50v.

If you would like to adjust the threshold level setting higher, hold down the mode button for an extended push until you hear a beep. Repeat this step 3 more times until you see 1.0 on the display.  Each subsequent quick press of the mode button will increase the preset voltage level setting. The settings loop from 0.2, to 0.5, to 1.0, to 2.0 to 5.0, to 10.0 and to 50.0.  Once you reach your desired threshold level setting, hold down the mode button again for an extended push until you hear a beep and you will be back in Power Probe Mode and ready to use your Power Probe.   Each time you re-connect your PP III to the vehicle’s battery the setting will default back to the last known setting.