Main relay, engine management system
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Main relay, engine management system
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When the ignition is turned to ON, the main relay is active. The following components are supplied with power from the main relay pin 87 via fuses 38 and 16b:
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Control module, EDC 15 (595)
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Accelerator pedal position sensor (379)
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Relay, A/C compressor (156)
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Mass air flow sensor (205)
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Intake air temperature sensor (407)
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Control module, glow plugs (596)
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Control valve, charge air (179a)
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Control valve, exhaust gas recirculation (404)
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Control valve, swirl throttle (403)
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When the ignition is turned to OFF, +15 on pin 39 will go low and the afterrunning function in the engine management control module will start. Only after the afterrunning function has expired, will the control module deactivate the main relay, de-energizing the control module. This takes approximately one minute from the ignition being turned to OFF. Diagnostic communication is operational during the afterrunning period.
If a fault occurs in the main relay circuit, one of the following diagnostic trouble codes can be generated
P1625 Main relay. No voltage to control module pin 3.
P1626 Main relay. Voltage drop too late
