Glow Plugs and now dealers dont know!

[leicschris]

Hi All

car - 2001 W220 Mercedes S320cdi

The issue I have is that I have no glow plug light in the dash ever, and have had recent starting problems, although not this week, but the dash light is still not working.

I have changed the relay/control module for a used one which I was told was working, and changed the temperature sensor for a genuine Mercedes one, which seems to have helped the starting first thing in the morning although I am worrying about the winter.

Today I put the car into Mercedes Leicester for a star report and diagnosis, which did not seem to be any help at all. I didn't understand the service reception guy who didn't seem coherent in his definition, or inspire confidence in his knowledge and Mercedes seemed keen to keep their technicians to themselves!

They told me that at first a fault showed with glowplug number six on the star and as I had used a second hand relay/control unit that when they tested the car with a new control unit all the faults went away on star but they couldn't get the glow plug light to light on the dash.

They don't know why the dash bulb will not light, and said they had the instrument cluster out but someone previously had done something to the cluster and they didn't know what, so they would change the instrument cluster.

I can accept the possibility that the relay/controller could be suspect even though the breaker told me it was tested and working but I don't understand what could have been done to the cluster that Mercedes looking at it couldn't tell what it was.

Asking a simple question like "Is the bulb blown", "Was there a bulb there" and "Is the glow plug light a separate bulb in the cluster, or part of a unit" couldn't get a direct answer from the service receptionist, just we don't know what is causing it, but the must be an issue somewhere!, Yep, that's why I was there!

It is my understanding that the main ECU looks to the engine coolant temperature sensor and depending on the answer it decides to power the glow plug relay to turn on the glow plugs, and to turn on the glow plug light on the dash. It is for this reason that I changed the temperature sensor in case it was sending false readings to the ecu.

I would have thought it would have been quite easy for Mercedes to test a bulb and/or determine if the relevant wires were showing power to the connector, and that any previous bodges would be obvious.

I would remove the cluster myself and look but the dealers wouldn't sell me the removal tool and the one I bought on ebay which said radio key is not up to the job and is too thin and wont remove the cluster.

Any ideas guys

Thanks

Chris

 

[nick mercedes]

Take it to someone who knows what they are doing WDM Cars in Birmingham for example.

 

[Harlowcabbie]

I was able to pull my cluster out by making two hook tools using an old coat hanger . Sounds like a horrible idea I know but it worked perfectly .

 

[jaymanek]

Trying to remember a w220 cluster, think it uses radio pins to pull it out?

 

[leicschris]

Hi All

thanks for the replies

I did think the main dealers would know what they were doing, just disappointed with their service. I have some family flying in from Ireland tomorrow for a few days so the car will be busy. was thinking of letting is it Mercland in Nuneaton look at it as they are closer.

it is radio keys that fit the cluster but the ones I bought were thin and flimsy and although you can hear them click they bend and wont pull the cluster out. Guess thats what you get for a couple of quid.

I've seen lots of posts about glow plug lights staying on, but none about the lights not lighting, even though the owners manual states this shows a fault and tells you to take it to a dealers!

I did think it could be an ecu fault but the star report claims no fault in the ecu or the instrument cluster

thanks

Chris

 

[Dieselman]

Do you realise a CDi doesn't need glowplugs in all but very, very cold weather.

 

[ItalianTuneUp]

Do you realise a CDi doesn't need glowplugs in all but very, very cold weather.

Good to know that.

My same model but MY2005 car has the opposite issue: glow plug light comes on occasionally at seemingly random times. I had the glow plugs replaced but it seemed to make no difference to the dash light coming on from time to time. Probably nothing to worry about, but still a bit annoying. Any ideas as to the most likely cause?

 

[bob6600]

Hi All

thanks for the replies

I did think the main dealers would know what they were doing, just disappointed with their service. I have some family flying in from Ireland tomorrow for a few days so the car will be busy. was thinking of letting is it Mercland in Nuneaton look at it as they are closer.

it is radio keys that fit the cluster but the ones I bought were thin and flimsy and although you can hear them click they bend and wont pull the cluster out. Guess thats what you get for a couple of quid.

I've seen lots of posts about glow plug lights staying on, but none about the lights not lighting, even though the owners manual states this shows a fault and tells you to take it to a dealers!

I did think it could be an ecu fault but the star report claims no fault in the ecu or the instrument cluster

thanks

Chris

I don't really trust your dealer's diagnostic as they are either trying to sell you a cluster that is most likely not needed or do not know what they are doing.

When you switch your ignition on, all lights should come on. If the glow plug light does not then as you have thought it could well simply be a bulb.

Take it to Mercland, Jay will at least get it diagnosed properly

 

[leicschris]

Hi
Yea I don't trust the diagnosis either, of they had said the bulb is not blown but it's not getting power then that would be a start, but to not know!

I'll phone jay next week and see when I can get it booked in.

I was happy to buy a new relay unit if that solved the problem bit when I asked if something could be breaking the relays and if I spent £150 on a new one could they confirm it won't be broken by a fault they just looked at me blankly

I know the cdi engine can start without glow plugs in the warmer weather and that could account for why it does now. It's the winter I'm trying to prepare for

Chris

 

[Dieselman]

A Cdi isn't going to need glowplugs in any UK temperatures.

 

[WG M-B]

A Cdi isn't going to need glowplugs in any UK temperatures.

Unless its a 642 engine

 

[WG M-B]

And are you sure it's not as simple as someone turning the glow lamp indicator off??

 

[leicschris]

And are you sure it's not as simple as someone turning the glow lamp indicator off??

Hi
No, I don't know if someone has turned the glow lamp indicator off though wouldnt that be something the dealers would have checked!

makes me wish I had a star system of my own

Chris

 

[panason1c]

As cdi engines will start perfectly normally without g/plugs, I would ensure that the glowplugs were actually being energized when ignition is turned on (they also remain energized for a few seconds after engine start-up)

With a cold engine, disconnect any one of the g/plug leads from its g/plug and connect a tester between the lead and earth to check for 12v when ignition is turned on, leave ignition on and power to the lead should shut off after a short while (perhaps 30 seconds or so?)
This test will at least ensure that the g/plugs are actually receiving power and my attention would then go to the cluster side of things (check cluster connections,bulb, etc) if all ok with the g/plugs.

If the above shows no power to the g/plug leads then the fault is somewhere else and would possibly explain why the dash light isnt working. (possibly a problem with the main power supply to the relay)

 

[HarpreetSingh]

Dude, Leicester Merc are a rip off and a half- as already said you could try merc land or premier service who are MB specialists (and I mean real MB specialists, no BS like some people) over on the troon industrial estate, I've used them and they've been ace!

 

[leicschris]

Hi All

Just to update you all, problem is still not solved and car wouldn't start yesterday again.

I called Jay at Mercland and was planning to bring the car to them when I got it started, and then received a call from Leicester Mercedes as my other half had telephoned Mercedes UK to complain about the service received from them, and Mercedes Leicester have asked me to bring the car into them next week for two days free of charge so that they can diagnosis the problem, and offered a courtesy car while they have mine.

I will update when it returns and I know what the issue is.

One thing I learnt from Jay is that the instrument cluster does not have a glow plug bulb but an LED, so I may have a faulty cluster which needs repairing, but I'm not sure the cluster has anything to do with starting, just showing the warning light or not.

regards

Chris

 

[SilverSaloon]

MB Leister sounds like they havnt got a clue, and after looking at it will advise stuff that may or may not actually need replacing.

I'd see what they say, and if the cost seems pricey, i'd get a 2nd opinion.

Is the glowplug relay plugged in?

 

[BlackC55]

I'd put money on the cluster being at fault.

I think the starting issue is something very different. Air in fuel pipes, injestor leaking off too much, fuel rail sensor or high pressure pump.

 

[96catai]

More info:
Thanks for download!

 

[grumpyoldgit]

More info:
Thanks for download!

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