Can I bypass the OVP
 

hello,
1987 190D NON turbo-
My AC quit working at the same time I started experiencing a rough idle.
(my tach has been broke for over a year)
I am pretty sure it is the OVP. If anyone has another opinion, I am open to listen.


I have looked for an OVP on Pelican Parts, but cant find one. I have looked at other sites (ebay, Amazon etc) and there seems to be a discrepancy as to whether the OVP has the same part number for a turbo and non turbo. Does anyone know the part number for a 1987 190D NON turbo 2.5?
If you have a used one, I am open to buying it.


Can I bypass the OVP to test?
Can I bypass the OVP permanently?

The OVP should be the same for ALL cars of the same era. It is chassis-specific, not engine-specific. Any OVP for any W201 should fit, probably the exact same part for the 123,126, and 124 cars too.

Can you bypass it? Yes. Should you? No.

This is what I know whatever it's worth.

1) ovp can cause rough idle, I experienced it on a w126 but I gather it could be mechanical.
2) kilma on w201 controls the tach. So it could be the kilma relay.
3) kilma controls the ac also.

I have used one from w124 and w126 if you need one. I am not sure they are compatible with w201. My 84 190D don't have ovp. PM me if interested.

I'm pretty sure that all 2.5's used the same part, 2015403745. Pelican stocks three or four brands, just search with that part number.

OVP also supplies power to the idle computer (which supplies speed signals to the Klima and tach, the Klima does not supply the tach) and antilock system. Best to replace the OVP and go from there.

Hang a volt meter on the battery to see if you are actually going over voltage.

Also hang an incandescent light ( not LED ) + a volt meter on pin 87 ( or farther down stream ) to determine if the relay is dropping out.

Most older cars regardless of brand don't have a OVP so if you are attentive to the volt meter, there is little risk during testing. Look at post 19 in the link below for a diagram and even a way to test a OVP. https://www.peachparts.com/shopforum/tech-help/177089-testing-ovp.html

See my other posts in the thread above for more info.

For testing of the car side when bypassing a OVP, you will need to jumper 30 ( Battery ) and 87 ( idle controller and other loads ) It would be wise to insert a 10 amp fuse in the jumper as you will be eliminating the existing fuse. You will also need to jumper and unjumper each time you run the car as the OVP coil receives switched power and 30 is constant battery.

In theory, you could jumper 15 to 87 and not have to deal with adding / removing a jumper each time you drive however, there might be too many loads in 15 to tolerate another load.

Thanks to all that Replied.
I purchased an OVP.