Glow plug warning light W124 E300 Diesel

[3 phase]

Have tried finding a thread on this but no luck.
Just started the car and when I turned the key no glow plug light. So waited 10 seconds tried again no warning light. So I tried starting it and the engine started fine, (outside temperature 19 degrees C).
Then after about 20 seconds of running, the light came on for about 10 seconds then went out and remained out. When we returned to the car later the same scenario happened again. Does anyone have any ideas?

 

[Dieselman]

Suspect the glow relay. The dashboard light is only and indicator to the driver, the plugs may still be working fine but it needs checking to see.

 

[3 phase]

Thanks dieselman, can you give me a any clue where its sited and which one I should be looking for??

 

[Dieselman]

Item 57, mounted on the n/s inner wing. Meter the output first to see what's going on.

 

[3 phase]

Thanks very much indeed for your help. Merry Christmas.

Ade

 

[Number_Cruncher]

One thing to check carefully before condemning the glow plug relay/controller is that the engine wiring harness hasn't failed.

The glow plug relay expects to be able to read the engine's temperature from the coolant temperature sensor which is located under the inlet manifold, near the back of the cylinder head. This is exactly the area of the wiring loom that degrades first (possibly because it gets hotter).

You should be able to read the resistance of the coolant temperature sensor from the wiring connector at the glow plug relay, i.e., you shouldn't need to do any stripping down of parts to check it, and if there's a problem, you'll most probably find the wires have shorted together.

On my 1995 E300D, I found the wiring at the coolant temperature sensor was in a really bad state, and I fitted a new engine wiring loom, the price for which was about £300.

 

[3 phase]

Found the relay as you detailed dieselman, thought I would remove it and make sure all was clean and also took a good look at the loom as detailed by numbercruncher, then put the relay back and everything now is Ok and performing as it should. The loom looks to be almost brand new, so maybe it was replaced before I took possession 10 weeks ago.
Thanks for your help again.

Ade

 

[Number_Cruncher]

>>The loom looks to be almost brand new

On the new loom I fitted, there was a white wraparound plastic sticker on the loom, just by the multiplug, which is in the compartment with the brake servo and the duo-valve. On this sticker there was the date when the loom was manufactured.

My loom looked good - until I took the manifold off, and looked at the area by the temperature sensor. Did you take the manifold off?

A system that didn't work, was disturbed, and now works again, to me strongly suggests either a problem with the wiring or a poor connection.

 

[3 phase]

Yeah, take your point on that, I didn't pull or prod the loom, just the relay contacts, but the car is at our friends after taking a taxi home last night, will have a look at the date of manufacture when I go to pick up this morning, thanks again.