Preglow relay interchange: w201 to w123?
 

I have been having some possible relay issues (another thread) and I just found my spare preglow relay... which turns out to be for a 190d, based on my check of the part number (005 545 18 32).

Two questions:
- any impediment to using it?
- did the 190d system have a post-glow function built in (relay stays activated and plugs hot for a while after startup)? If so, for how long?

Thanks

If the relay has 5 pins in the smaller connector, it's an afterglow relay. The fifth pin, actually marked pin 6 since space 5 is blank, is for a coolant temp sensor. Afterglow time is determined primarily by coolant temp. FWIW, preglow indicator time is more dependent on engine temp than in a conventional relay. If you restart a hot engine, you might not notice the preglow indicator come on because it'll go off very quickly even if the plugs are still energized. I don't know if preglow cycle time varies with engine temp or is different from the maximum cycle time of a conventional relay.

If it fits, try it.

Sixto
87 300D

It's four live pins on the small plug. Thanks for the quick reply.