FUSO 4M4 – INTAKE AND EXHAUST – TURBOCHARGER CONTROL SYSTEM – Diagnostic Precautions

2. Diagnostic Precautions
• Before measuring voltage, check the battery for charged condition and specific gravity. If system inspection is performed with the battery uncharged or reduced in specific gravity, accurate measurements cannot be achieved.
• Before disconnecting battery cables, harnesses and connectors, set the starter switch to LOCK or OFF, then allow at least 20 seconds.
• To avoid having electrical parts damaged, set the starter switch and lighting switch to LOCK or OFF before reconnecting battery cables, harnesses and connectors.
• When performing measurement with the tester, handle the test bar carefully so that it does not damage internal circuit and other electrical parts of the electronic control unit to result in a short-circuit failure between terminals in connector or between connector and car body.
• Resistance is affected by temperature. Determine the necessity of resistance measurement following given temperature specification as a guide. Otherwise, use normal temperature (10 to 35°C) as the measuring condition.
• To start the engine, be sure to connect the connector of the MPROP (rail pressure control valve) to the engine harness. If the engine is started without connecting the MPROP connector, the engine electronic control unit can-not control the supply pump and the fault of the engine may result.
• If the electronic control unit is replaced with a new one, some data must be registered in the new electronic control unit for proper engine control. This also applied to the case when replacing the electronic control unit with the one that has been used in other vehicle. (See Gr13.)

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