Hello fine people,

On my 1991 W124 300D...

Today I went to change the oil and filter as usual.

I took it off the hoist and started it as normal...

The glow plug cycle light went on as usual and went off, I started the engine but a few seconds later the light came back on.

The relay has been replaced less than a year ago "old one stopped working".

The unusual thing is that the light goes off when I am accelerating /driving over 50 kms/h.

I checked the battary as it was low on charge. Replaced it with a fully charged one but I still get the light back on after the engine starts and the light goes off when driving as mentioned above.

Using DVM all 6 pins read 7.5V when the light comes on the second time.

The relay sounds a click when the light comes back on.

What could be the cause please

Regards,

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* 1991 W124 300D 480.000 kms Running on WVO
* 1991 W124 300D 230.000 kms Running on Diesel
* 1997 W210 E300 280.000 kms Running on Diesel