Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

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Engine Control Module: 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.

Trouble Shooting Chart:





6. Use the chart for diode flash code information.
7. After test drive, check and repair indicated problem and retest.
8. Disconnect the test diode. Fault codes will be erased as soon as the engine is turned off.