ah-kay-

If you note, the replacement relay does the same thing as this mod - it's referred to as 'after-glow'. It helps smooth running a cold engine, especially at lower temps. And it doesn't have to be permanent, just until all the other problems are found and corrected. The idea is to isolate down to a minimal circuit where the problem is still exhibited and can then be found. This part of the glow plug circuit shouldn't be drawing much current and it seems to be doing just that. So removing the connection has a two-fold purpose. Once he's happy with his circuit, he can reinstall the GP relay connection and decide if he needs go further. Besides, he seems to have found a large voltage drop in the solenoid wire already, so he's on the right track.

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mjk

'84 300SD 119KMi (Liesl der Diesel)
'84 300D 326KMi when the oil left (former parts car)
'82 300SD 253KMi (new parts car)