Main relay, engine management system
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Main relay, engine management system
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At voltage feed +30, the main relay is the key. Power is supplied from main relay pin 87 via fuses 38 and 16b to the following components.
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Control module and diesel pump, PSG 16 (595)
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Mass air flow sensor (205)
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Control module, glow plugs (596)
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Charge air control valve (179a)
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Control valve, swirl throttle (403)
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When the ignition key is switched to the OFF position, +15 disappears from pin 16. The afterrun then starts in the engine control module. It is not until the afterrun is complete that the control module closes the main relay and the control module is without power. This takes approximately one minute after the ignition key is turned to the OFF position. Diagnostic communication is functional during the afterrun.
If a fault occurs in the main relay circuit, one of the following DTCs can be generated
P1652 Main relay. Voltage drop too late.
P1653 Main relay. No voltage to the control module.
