Hi Guys,

Bought my first Merc about 4 months ago, loving the experience, but have a nagging Fault, its getting hard to start over the last few weeks. I'm a technical engineer so not clueless, but when I took the engine cover of the engine, I was taken back at just how complex and big it was! hardley any room around it to work! OK poor starting hmm I thought id do the basics, checked the air filter (fine) thought id check the Glow Plugs, reading up on the web there supposed to have a low resistance if ok and be open circut if defective, well I could only get to the inner three, but they read ok 0.8, 0.4, 0.6 Ohms. So seem ok,

So I thought id check the voltage to them, Bingo! 0 volts, checked it properly, imediately ignition switched on G-Plug led up on dash but 0 volts, infact switching back to Ohms it was 0 Ohms ie connected to earth! hmm, so a couple of questions, how to identify the relay in question??
(I have just ordered a manual) I already metered out all the fuses in the box top left of engine bay there all ok, im guessing the relay isnt firing up and guessing when its not activated it pulls the plugs down to earth? I also read that the load can be 60amps, so a failed relay at 100k miles wouldnt supprise.

There are things I dont know about these glow plugs, I know the led comes on in the dash to allow time for them to heat up, fair enough,
but in modern engines there also used to improve emissions, so do they remain powered up? or is it the heat of combustion that keeps them doing there job??,

Hope someone out there has some understanding

Many Thanks Mark....

 

Hi Guys,

Didnt get any help, but by the poweres of the internet, traced the issue to the glow plug relay, the timer board has a blown resistor, so eurocar parts can supply for £80.20,