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Overvoltage Protection Relay
Function
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.
Diagrams and Pinout
Pinout
| 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) |
