Help me techno-wizards!!
What is the function of the overvoltage relay (I've seen it mentioned many times on the board) and what can be effected if the overvoltage relay goes bad?

I'll be I'm not the only one who is in the dark on this...



------------------
Jay Yambrovich
1989 300 E
1992 190-E 2.3

Basicly it's a protection device for the computers. It's there to keep excessive voltage spikes from damaging them.

You should interface with fiver64; check out his thread. Also, I found a search on, "protection relay ABS" produced some good background info. Cheers, Andrew Seidel.

------------------
89 190E 2.6
83 300TD Turbo
75 240D

The OVP (overvoltage protection) relay uses a Zener diode to act as a voltage regulator, spike suppressor. The diode allows current above a certain voltage to pass through the fuse to ground. Small spikes are just shunted larger ones blow the fuse.

The device is similar to a UPS (uninterruptable power source/whatever) for the car computors that are hooked to it.

The reason it causes so much problems (amongst those not familiar) is that the main system affected (KE-Jet) works rather well without electronic control. It looses all its enrichment schemes; most noticably cold start/warm-up enrichment.