| Notes on general repair work on vehicles fitted with auxiliary heater |
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| If parts of the fuel system have been removed or replaced, make sure that all components used for diverting fuel to the auxiliary heater are properly installed. The auxiliary heater is then to be switched on and operated at full load for at least 10 minutes to ensure complete bleeding of the fuel pipe. Operation of the auxiliary heater is also to be checked. |
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| After performing repairs in the area of the auxiliary heater fuel pipe, check that: |
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| There is no air in the fuel pipe to the auxiliary heater. |
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| The fuel pipes are flush with the underbody and protected against mechanical damage. |
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| The fuel pipe to the auxiliary heater is protected against heat generation which could affect operation. |
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| The fuel pipe is not making contact with components which become warm. |
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| When performing repair work in the area of the fuel delivery unit, pay attention to correct routing of the pipe for diverting fuel to the auxiliary heater in the fuel tank. If the pipe is not routed properly, the metering pump -V54- may only supply fuel if the tank is completely full (if this is not the case, no fuel is supplied and the auxiliary heater is deactivated on account of a fault) → Chapter. |
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| After removing and installing fuel system components, the auxiliary heater is to be switched on and operated at full load for at least 10 minutes to ensure complete bleeding of the fuel pipe. |
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| If there is not enough fuel in the tank (fuel gauge in control unit in dash panel insert -J285- in “red zone”), the supplementary heater control unit -J364- does not activate the auxiliary heater (activation prohibited by way of the data bus on account of a lack of fuel). |
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| Prior to activation and during operation of the auxiliary heater, the supplementary heater control unit -J364- interrogates the data bus diagnostic interface -J533- / battery monitor control unit -J367- via the data bus. As soon as the data bus diagnostic interface -J533- transmits a request for energy saving on account of a no longer adequately charged battery or insufficient electrical system voltage, the supplementary heater control unit -J364- switches off the auxiliary heater. |
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