Skybound: Nevermind. I think it stands for Over Voltage Protection relay. Correct me if I'm wrong. Where is that located on the 400E and could that be the cause of a continuous engine stumble or miss? Thanks.

[QUOTE=emerydc8;1513722]Pete: I have a 1993 400E with 229,000 miles on it. During the recent process of replacing the water pump and power steering pump, I think I may have disturbed the wiring harness, because it's got a miss now. I ordered the harness from MercedesShop today and hopefully it will arrive by 2nd day air by the long holiday weekend. Any tips on where to start with the harness replacement? Thanks.

Take the air cleaner assembly off and everything will be abundantly clear. All you will need in the way of tools is an allen wrench and a phillips screwdriver.

Thanks, Pete!

400E's do not have an OVP.

Thanks. After reading other posts, I see that it was integrated into where the computer cards sit.

Just got my wiring harness today and replaced it in about an hour. As someone previously mentioned, the hardest part--and it wasn't even that hard--was to remove the harness end (canon plug) where it plugs in behind the firewall. There is a breather hose on the right rear side of my valve cover and the beautifully-engineered canon plug wouldn't fit by that hose. I either had to remove the hose and risk cracking it, or go the other direction and pull the wires out towards the back, which is what I chose to do.

As you can see the insulation flaked off as soon as I touched it. The main line, closer to the canon plug, was not in good shape either, but it certainly wasn't as bad as where the wires were exposed to all the engine compartment heat. I will repeat what someone else said: it's hard to believe the car even ran with the old harness. I guess I was lucky after 229,000 miles.

As Mercedes says "There's nothing to see here,,, keep on moving."