Overvoltage Protection Relay

A 5, 7, or 9-pin overvoltage protection relay is installed depending on the vehicle model and special equipment. This relay protects the control units (ABS, CIS-E, etc.) from excessively high voltage.

The battery voltage is present continuously at relay terminal 30. With the 7 and 9-pin versions the battery voltage is also connected to terminal 30a over the 10 A flat plug-in fuse. When the ignition/starter switch is turned to position 2 (driving position), the voltage is present at terminal 15 causing the relay to pull in. Power is supplied to terminals 87 (5-pin version) or 87E and 87L (7 and 9-pin versions).

Voltages > 22 V in the vehicle electrical system are connected directly to ground by the Z diode (fuse defective).

In the event of overloads occurring after the overvoltage cutout, the circuit is interrupted by the 10 A flat plug-in fuse. The 9-pin version is also fused separately at terminals 87E and 87L, whereby when the fuse for 87E blows 87L is also switched off.


Pin Function
30 Battery voltage input (12 V)
31 Ground
15 Ignition switch input
87E Fused and diode protected output (12 V)
87L Fused and diode protected output (12 V)
30a Fused output (12 V)
OVP pinout
5-pin OVP
7-pin OVP
9-pin OVP

The following procedure is a static test for basic relay operation. Passing the following test does not guarantee that the OVP relay is functioning correctly, but will accurately tell if the OVP relay is faulty.

  1. Apply 12V to pin 30 and ground 31
    1. Verify with a multimeter that 30a has 12V and 87E/87L has no voltage
  2. Apply 12V to pin 15
    1. The internal relay should click
    2. Verify with a multimeter that 87E and 87L have 12V as well as 30a.

Part Numbers for OVP Relay

Part Number Description
201 540 32 45 7-pin relay, black top, single 10A fuse
201 540 38 45 7-pin relay, black top, single 10A fuse
201 540 37 45 9-pin relay, red top, double 10A fuse
  • articles/overvoltage_protection_relay.txt
  • Last modified: 2020/11/17 00:49
  • by john5788