W211 Glow Plug Relay (Well sort of) 2.7CDi 2003

[X308]

Greetings,

Sorry, I know very little about Mercedes

This afternoon I attempted the repair of a glow plug relay on my mother in laws W211.

I replaced the glow plugs and repaired the blown fuse inside the relay with some 30amp fusewire.

As I was putting it all back together I made the novice error of arcing the 12v relay input voltage wire retaining nut against the relay housing fixing thread. It arced like a good one and eventually welded itself together.

Having separated the two items I am no longer getting any voltage to the relay. Of course the relay could be fried now but I would expect there to still be power coming into it.

So my question is - Is there *something* between the relay and the battery, a fuse or relay. I have checked all the fuses which seem intact and the car starts and runs fine.
Is the voltage to the relay constant, in pos 1 or 11, or *sent* when required subject to the engine temperature as defined by the CTS?

Is there anywhere I can get a (free) copy of the wiring schematics?

Best wishes for the new year people.

Regards,


X308

 

[mersum1es]

pre fuse box is found in passenger footwell, there are few main voltage feeds coming from batter with 'big' fuses, cannot remember specific lines. Are you getting voltage to big wire coming to relay (main feed I assume)? I think it should be constant, ecu is then controlling relay via small connector? It is many years since I was messing with my W210 relay, cannot recall all...

 

[X308]

pre fuse box is found in passenger footwell, there are few main voltage feeds coming from batter with 'big' fuses, cannot remember specific lines. Are you getting voltage to big wire coming to relay (main feed I assume)? I think it should be constant, ecu is then controlling relay via small connector? It is many years since I was messing with my W210 relay, cannot recall all...

Hello and thank you for your reply.

Currently I am getting nothing (key in or out and in any position) and no feed to the relay. From what I have read the F32 fuse box is the next place to look although it involves lifting the carpet and as it is raining here currently. I will give if a miss 'till it clears up.

Judging by an article I have read*, there is nothing glow plug specific there?

*I am unable to link to said article as I assume there is some anti spam software in operation preventing new users posting links until <x posts is reached

 

[X308]

*I am unable to link to said article as I assume there is some anti spam software in operation preventing new users posting links until <x posts is reached

Please add this link when moderated

http://mbfan.ru/Instruktsii/W211_ Dual Battery_ABC.pdf

 

[X308]

I managed to find some time between the showers to pull out the drivers floor and expose the Fuse 32 set up. My interest had been sparked by THIS information which lists

69 - Valid for engine 629, 642, 646 EVO:Glow time output stage

I have no idea what engine number the 2.7 is but it was worth a punt.

69 is the black cable with blue marking. 69 Has no voltage output, in any key position. Whilst I was at it I checked all the fuses which were ok.

The three other cables all showed a voltage output.

I ran a continuity test from cable 69 to my glow plug relay and sure enough it appears to be the source of the power to the relay.

So, where am I. Well I wanted to take the fuse box out to open it to see if there were any hidden fuses inside of at the least if I had fried the cable 69 circuit. I was not able to do this as the fusebox is secured through the chassis and I needed access from below. I was keen but not that keen to get the ramps out!

What I am after is if anyone has opened one of these boxes before or has any knowledge as to whether or not there is anything inside that could have fried? The document I highlighted earlier suggest a 150AMP fuse.

EDIT: I guess this answers the question;

Regards,



X308

 

[Uncle Benz]

That does indeed answer your question. The only advice I would offer is PLEASE disconnect the battery this time before removing any of the big cables. The large incomer at the bottom will have no fuse in its line from the battery. If you short that one to the surrounding metalwork you'll give yourself a fine new-year firework display!

 

[mersum1es]

your engine is OM 647, but I think W211 model has similar system in all diesels

 

[Botus]

what a stupid place to put a connection box, sorry to hear the agro at least only £20 and a fight with the carpet

 

[X308]

Thanks for your comments, all back together again and working great.

The only advice I would offer is PLEASE disconnect the battery this time before removing any of the big cables. The large incomer at the bottom will have no fuse in its line from the battery. If you short that one to the surrounding metalwork you'll give yourself a fine new-year firework display!

Fortunately I did not repeat my earlier err, although getting the fusebox out of the car (need to access underneath too) did tempt me at times to set fire to the bleeding thing!

your engine is OM 647, but I think W211 model has similar system in all diesels

Thanks - Odd it was not listed, however I can confirm it should be.

what a stupid place to put a connection box, sorry to hear the agro at least only £20 and a fight with the carpet

It is. It is under the right footwell carpet, left or right hand drive. In fairness it only takes 5 minutes as I am an expert now, having done it three times. The footwell carpet slides out as a whole which makes it alot easier.

 

[ray-x777]

Thanks for your comments, all back together again and working great.



Fortunately I did not repeat my earlier err, although getting the fusebox out of the car (need to access underneath too) did tempt me at times to set fire to the bleeding thing!



Thanks - Odd it was not listed, however I can confirm it should be.



It is. It is under the right footwell carpet, left or right hand drive. In fairness it only takes 5 minutes as I am an expert now, having done it three times. The footwell carpet slides out as a whole which makes it alot easier.

hi. i did the same mistake when putting back the relay and arced the same like in yours. what did you find? how did you fixed it? was the relay good or was fried? thanks