Jumpstarting fry ovp relay?
 

I recently jumpstarted my 87 300e and soon after I experienced a rough idle. My abs light would light up on a few occasions. I suspect this is my ovp. Could anyone tell me how to replace this fuse. I know it;s located somewhere behind the battery. Thanks

The fuse, or fuses depending on which OVP you have, is mounted under the red cap on the OVP. Simple 10a blade fuses. Not sure where the OVP is located on your car.

If the ABS light would come on 'on a few occasions', I doubt you'll find the fuse bad. The OVP 'relay' itself is likely bad, and usually it is internal cracked solder joints. If you can solder, this problem is repairable, IF you can get the OVP case off. A consideration though is that an improper jump could have damaged the internal zener diodes - replacement would then be best.

Steve

I missed the "on occasions" part. Blame speed reading.

Pull the OVP and shake it. If you hear rattling, it's bad - replace it.

This is not a conclusive test, but again, if you hear rattling when shaken, it's a goner.

I pulled the ovp relay out and the fuse seems to be fine. I also shook the relay and no rattling sound. Is there any other way to tell if the relay is defective? My idle is still rough when put I put the transmission in drive and the rps houver around 500 rpm. Other symptoms include the occasional antilock brake light coming on and bad gas mileage. Please help.

Your OVP can be affected by jump starting, usually I think it's just the fuse though. Test the fuse in case it's damaged where you can't see it (this can happen).

Russell

Typical is internal cold solder joints. Those cannot be diagnosed or fixed without disassembly. The altrnative is to replace it.

Bad contact in the OVP - which powers the fuel control computer, ABS computer - will upset various things in loop control, such as the rotary idle air valve.

Steve