| Problem | Likely Cause | Solution per Manual | | :--- | :--- | :--- | | | Dead 9V battery or open fuse | Replace the battery. If still dead, check the internal fuse near the battery terminals. | | Inaccurate resistance reading | Test leads have resistance; low battery | Use the REL mode to zero out lead resistance. Replace the 9V battery. | | No continuity beep | Meter not in continuity mode; blown fuse | Ensure the rotary switch is on the continuity symbol (not ohms). Check the mA or A fuse. | | “OL” on display | Overload; measurement out of range | Select a higher range (if manual ranging) or check if the circuit is open (for resistance). | | Fluctuating voltage reading | Low battery; dirty test leads; EMI | Replace battery, clean leads, move away from motors or VFD drives. |
: Turn the vehicle ignition to the "ON" position (do not start the engine). The scanner should power up automatically. Mac tools et97 user Manual
Essential for identifying "dead" batteries or verifying that power is reaching a specific component, such as a fuel pump or headlight. | Problem | Likely Cause | Solution per