Flickering Glow Plug Light

[will_t]

The other day the glow plug light in my 85 300d coupe started flickering. It happens with some regularity, though I don't see a particular pattern. And it comes and goes, like every few minutes.

Anyone know why it would be doing this?

Thanks,

[Carpenterman]

I have this same problem. I've checked and double-checked the wiring and swapped in a known-good relay from my parts car--all to no avail.

I think the problem is the ignition switch. I can push up on the key and get the light to go off, so I believe there is a contact problem inside the switch.

Try manipulating the key when the light flickers and see if that affects it.

[will_t]

Originally Posted by Carpenterman

I have this same problem. I've checked and double-checked the wiring and swapped in a known-good relay from my parts car--all to no avail.

I think the problem is the ignition switch. I can push up on the key and get the light to go off, so I believe there is a contact problem inside the switch.

Try manipulating the key when the light flickers and see if that affects it.

I'll give that a try. Thanks!

[Diesel911]

You can get a cheap Volt/Ohm Meter and check the resistance of the Glow Plugs. I don't recommend buying parts there but Diesel Giant has a good Pictorial on Glow Plug Repair that tells you how to ceck them from the Connector at the Glow Plug Relay. About a 2-5 min job.

The Manual has if the GP Light as abnormal when you are preglowing it is the Glow Plugs.
If the Lignt comes on after the Car is running it is a problem in the Relay. The exception is if you have a year and model that has the Afterglow feature.

It is well accepted that Carbon build up is bad for Glow Plugs. In the below section is ways to clean out the Glow Plug Hole.

Repair Links
Fast navigation Fast navigation Do It Yourself Links

[Maxbumpo]

How rapidly does it flicker?

If it comes on after the engine is running, stays on for a few seconds, and then goes out, that is the self-diagnosis telling you "Houston, we have a problem!".

[will_t]

Originally Posted by Maxbumpo

How rapidly does it flicker?

If it comes on after the engine is running, stays on for a few seconds, and then goes out, that is the self-diagnosis telling you "Houston, we have a problem!".

It flickers intermittently, every 5 to 10 seconds or so, though not with that kind of dependable regularity; it's more random. It doesn't really ever come completely on, rather, it flickers with partial power. It sort of reminds me of the warning light for a slightly failing generator or voltage regulator in an old gas car.

[psaboic]

I had that problem on my 83 300D and a new glow plug relay solved it......