Glow Plug Issue

[Phil Ratcliffe]

My 2018 MP went to our local garage for a service earlier this week and when i picked it up the glow plug light stayed on for a minute after starting, the manual says this is a glow plug module fault. This was purchased and fitted but the problem persists. I then booked the car in at my local Mercedes dealership and they diagnosed no power at the glow plug relay and wanted to check the fuse which they said was under the drivers seat which required its removal to get at the fuse, as they seemed unsure if this was the fault and it would take a few hours to achieve (there rate being £145 +VAT per hour) i decided i could do that. So yesterday i removed the drivers seat and side panels to the seat base but could not locate the 100 amp fuse for the Glow plug module. In desperation a friend of mind who is a retired motor mechanic came over and after removing the start battery we could not see any fuses, he suggested that we check for power at the glow plug module which indeed was seeing power, (so much for the Mercedes garage wanting to strip the seat out, why could they have not done that simple check)
So we still have the same problem, the glow plug module has been replaced and it has power, the fault code that comes up when plugging in the diagnostic kit is P064C which is described as failure of the glow plug module. I have several questions
1 Could it be an individual glow plug that has failed? if so should that have its own fault code?
2 In the Fuses Assignment Supplement the pre-fuse box (which contains the 100A fuse for the pre glow system) is shown under the drivers seat base, is that so
3 Is there a simple test for individual glow plugs?
Any help on this is gratefully received as we are due to go over to France in the MP next Thursday

 

[DogWagen]

It is worth looking at MBClub.co.uk - the fault will likely be common to W477 V-class, vito and possibly others with the same engine code. There are a number of tech specialists that contribute and may answer if you post a question.

You don't say where you are in the country but I would look towards an independent Mercedes specialist to help - again have a look on MBClub to see who is closest.

You can check glow plugs with a multimeter but you do need to know what the resistance should be - MBClub might help (have not looked)

Hope that helps,

 

[Phil Ratcliffe]

Thanks for the info, the MP goes to my local garage tomorrow for them to check the glow plugs, i read on the MBclub site that a failed plug often blows the glow plug module .