Mercedes 124 300D Glowplug warning light

[Wellbrook]

My 300D Mercedes with 116000miles has developed a fault with the glowplug system. When I turn on the ignition with a cold engine the glowplug warning light does not come on. I wait the usual 5 seconds and turn the key and the engine starts immediately and then the glowplug warning light comes on and stays on for several minutes ( at least 5). If I stop the engine after running for a couple of minutes then turn on the ignition the glowplug light comes on as normal and the goes out as normal and the car starts as normal. The problem could be either a faulty glowplug, a faulty temperature sensor, or a faulty control unit. Any ideas?

 

[RJR28/12]

Sounds like you have a glow plug not working.The light comes on after starting to tell you there is a fault as it runs a self check on the system.I would che the resistances of the glow plugs and see how many you need.

 

[psmart]

Check out the thread http://forums.mercedesclub.org.uk/showthread.php?t=18312

It points you to 2 other threads. Looks like your Relay might have gone, with you saying it stays on for 5 minutes. Normally it stays on for around 40 seconds when a glow plug is down.

 

[Wellbrook]

Thanks for replies on W124 glowplugs. I appear to have resolved the problem by cleaning the earth contact on the control unit and giving the vehicle a motorway run for 150 miles even though it took over 4 hours because of traffic congestion. I hope the problem will not return as it sounds as if there are problems changing glowplugs.