Cannot Find Overload Prot. Relay 85 500

[ambuldog]

Hello Everyone, new here, picked up 85 500 SEC idle surges up and down.
Read about a few remedies but I can not find OVP, this SEC is a euro version.
Any additional help greatly appreciated. Thanks !

[wbain]

The OVP should be between the two firewalls. It has an square aluminum cover and fuse(s) on top.

It's the OverVoltage Protection relay. In the rare case there is anything greater than 22 volts in the system, a 22 volt zener will conduct to ground through the fuse causing it to blow, it's a dead short. This protects the ECU and ABS computers. BTW, the ABS computer is visible between the two firewalls in the center. The ECU is neslted away behind the passenger side kick panel.

The OVP should be opened and resoldered and should the Fuel pump relay.

Next, you will need to check for vacuum leaks.

[mercedessd]

on that model it is in the fuse box. red top

[Don350SDL]

Can be a red cube relay when used for ABS, in the fuse box, or a taller silver relay with a red top and clear plastic cover and 10 amp fuse insude, between the firewalls about dead center, by the windshield.

Don

[ambuldog]

Thanks for the help, however, took the car to old timer in Ambler, PA. Bob Fox, he proceeded to tell me the engine in this car was an early 80's version ?
It hand no OVP, honest, I had bought one and gave it to him for his time. I replaced the Idle Contol Unit on fire wall and cleaned the Idle Control valve, runs like a champ, also my passenger side automatic seat belt deliverer started working again. Now i'm selling it.

[wbain]

That Idle Control Unit on the firewall is actually the ABS controller.

See page 3:

http://mb.braingears.com/126_DISC2/program/Chassis/42-700.pdf


The CIS-E control unit is inside the car behind the passenger side kick panel.