Knock Sensor: Testing and Inspection

In order to use the VOLVO tester diode #5280 (or equivalent) for fault tracing, the engine must be able to start.

Testing With Test Diode:

1. Connect test diode (VOLVO tool #5280) to the test connector located on the driver side wheel housing (yellow-red lead). Connect the red lead to the positive terminal of battery.
2. Run the test diode into the passenger compartment and close the hood.
3. Turn ignition ON. The diode should now display a steady light.
4. Start and run engine at 920 RPM. The diode should now turn off.
5. Drive the car a short distance under low and high engine load conditions.
6. If diode flashes a series of 4 flashes, check the knock sensor wiring. If wiring is OK, replace the knock sensor and recheck.
7. If diode continues to flash during a road test after replacing the knock sensor, replace the ignition control unit.