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Home >> Mazda >> 1991 >> 929 V6-3.0L DOHC >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Knock Sensor >> Testing and Inspection >> Component Inspection
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Component Inspection

If the engine "pings" excessively and base timing is okay, check the on-board diagnostic system. If either knock sensors or knock control unit experience a problem, malfunction code 05 will set.

Knock control unit input voltage can be checked at ECU terminal 2M. With ignition "ON" and engine running at idle, voltage should be 4.0 - 5.0V.

To perform a basic check, hook up a timing light and tap on the engine block near either sensor while observing the timing marks. Timing should retard when the artificial "knock" created by tapping is detected by a sensor and relayed to the knock control unit.