Glow plug light not coming on

Discussion in 'Sprinter' started by Bruce Salt, Jan 4, 2017.

  1. Bruce Salt

    Bruce Salt New Member

    My 2008 sprinter has an intermittent problem where the glow plug relay wont come on and as a consequence the starter motor wont engage . this seems to happen mainly when the motor is hot but not always. I removed the connecting plugs to the ecu and cleaned all the contacts/pins with contact cleaner which solved the problem for a short time. I have always managed to get started so far by just cycling the ignition key off and on until the glow plug relay engages and then the starter motor can be engaged. once started the motor performs normally
  2. Kajtek1

    Kajtek1 Active Member

    The starter should engage independently from glowing process, so lack of light likely is the result, not the reason.
    I would start with observing the voltage and clean all accessible connectors starting from the battery.
  3. Bruce Salt

    Bruce Salt New Member

    If the glow plug sequence does not happen correctly then the motor will not crank but if the sequence is correct there is no problem with engine starting which normally starts on the first or second crank. Is it possible that there is a faulty temperature sensor so that the engine is perceived as being very cold so that glow is always required. I live in a temperate climate and our lowest winter temperatures would very rarely get to zero degrees celcius. I will follow your advice and clean all possible connections.
  4. Bruce Salt

    Bruce Salt New Member

    I tracked the problem to the relay that supplies power to the ecu having an intermittent fault in the grounding circuit of the relay coil, the coil has 12vdc supplied to it at all times and is activated by grounding the other leg of the coil via it appears the ignition switch . I am unable to confirm this as I am unable to track down any decent circuit diagrams so at this point i have installed a temporary grounding switch in the wiring loom until i can find some additional information.

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