D E F

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Mr Bob, Aug 19, 2019.

  1. Mr Bob

    Mr Bob Light Load Member

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    Mar 17, 2015
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    Got a Volvo D11 with a P204713 code. Open circuit is noted. I can force a regen but it will revert back to derate. Anybody got a schematic on this?
    Just great now it has morphed into a P204900 code. I dont get it, troubleshooter says its mechanical but lists possible electrical problems.
    Circuit description
    When the aftertreatment selective catalytic reduction (SCR) system operates under normal conditions, the aftertreatment control module (ACM) monitors diesel exhaust fluid (DEF) dosing valve duty cycle and DEF pump control value. When the DEF dosing valve duty cycle increases above allowed threshold and the DEF pump control value decreases below expected threshold, the ACM stops DEF dosing and reports a fault. Only certain mechanical failure or blockage in the DEF dosing valve or DEF supply line from the DEF tank will result with this fault, it is not a indication of an electrical fault.

    Conditions for diagnostic trouble code (DTC)
    Short circuit to battery voltage on A137:44

    Observable symptoms
    No aftertreatment diesel exhaust fluid (DEF) dosage

    Probable cause
    1) Short circuit to voltage supply, Control wire (-)
    2) Short circuit to 5V, Control wire (-)
    3) Connector
    4) Wiring harness
    5) Aftertreatment DEF dosing valve
    6) Aftertreatment Control Module (ACM)
    Also the DEF pump does not run after engine shutdown.
    This truck is messed up , the engine fan rpm does not match the requested speed , some of the time, with no codes.
     
    Last edited: Aug 19, 2019
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