Sprinter Glow plug warning light staying on.

[sullivan]

Hello Everyone...
I currently drive a 2005 Sprinter 311cdi.No problems starting or driving but yesterday the glow plug warning light remained on after starting.No other symptoms.No flat battery etc..
I removed and replaced the 4 plugs .Checked the resistances 3 were 0.7ohms and 1 was 18-25ohms, so i assumed this was the problem.
But the light still comes on ... Is this fault stored in the memory?
I have looked around the engine bay and ive noticed there is one 3 wire connector next to the wiper motor above the inlet manifold (2 thicker red wires)that has serious traces of corrosion.. is this the wiring going to the glowplug relay??
Does the warning light have to be reset by MB?
Will this cause damage if i continue to drive it?

Any info our advise is much appreciated..
Thanks.

 

[dava]

Chances are if you had one or more glow plugs open cicuit then it may/will have burnt out the glow plug relay, from experience if this has happened we change this at the same time. It's located under the battery to get access remove the grill then the head light, they cost about £56 ish so it may be a good sense to change it. However, before doing that disconnect the battery for a few moments then reconnect it, it may clear the fault code but leave it in it's memory, worth a try.

PS, the only sure way to test glow plugs is put them across 12v, + to top of glow plug and - to threaded part if they glow red hot they are OK, if they dont, then no good, some just get warm. Why I say this your method would not prove they get realy hot.

 

[Xtractorfan]

If you are in any way handy atall these relays can be repaired , i've just done mine, there is a few good threads on here about repairing them thats if u are into that sort of thing, u need a slodering iron and a bucket of cold water .......... to dip ur fingers in when the iron slips

 

[sullivan]

Thank you for your quick response. Ill give it a try , if it doesnt work ill buy a relay.
Will it be ok to drive for the moment ?
( cant purchase till during the week)

 

[dava]

Hmmmmmm not sure, if the relay is open circuit could burn the glow plugs out as it would be feeding current to them constantly, put your meater back on and see if it is given feed all of the time.

 

[Bolide]

Chances are if you had one or more glow plugs open cicuit then it may/will have burnt out the glow plug relay

How does an open-circuit glow plug burn out a relay?

Nick Froome
www.w124.co.uk

 

[dava]

Ops! I meant giving a feed to the glow plugs.
I must remember to read what I type.

 

[Jacko918]

If they are getting a feed all the time then they won't just burn them out, they'll also flatten the battery. Just unplug the large multiplug from the relay if you need to drive it, and get a relay asap.

I normally test glow plugs for continunity with a multimeter by disconnecting the wire and putting the + lead on the tip of the plug and - lead on the engine block. If your meter beeps they may be ok, if it doesn't they are definately open circuit. This way saves removing them to test them and the reduces the possibilty of snapping one off if it's siezed when you didn't really need to remove it.

A Word of Warning: Just cos you get a beep doesn't mean that plug is good. Sometimes when these plugs burn out they short to plug casing, effectively creating a dead short, this obviously will give you continunity but as there is no resistance in a dead short it will burn out the glow plug relay. Probably welding the relay contacts together, keeping them on all the time. For this reason I never change a glow plug relay without changing ALL the glow plugs or at least removing them all and testing them like Dava said. I have seen more than one new glow plug relay ruined like this because the person didn't change all the plugs first aswell.

 

[Jacko918]

Also when fitting glow plugs, give them a light coating of Merc CDI injector grease, between the tapered seat near the bottom of the plug and the top of the plug threads, this will stop them siezing for next time and potentially snapping off in the head.

As the old saying goes "Prevention is better than cure"