Further information
The PP line comprises a circuit designed to indicate to the OBC the connection status of the EVSE charging cable.
A connection is made between the vehicle and EVSE by pushing a Type 1 charging cable connector into the vehicle's charging port.
The two are disconnected by:
- Depressing a button on the Type 1 charging cable connector, which releases the connector and signals to the vehicle's On-Board Charger (OBC) to stop charging.
- Removing the charging cable connector from the vehicle's charging port.
The PP line functionality can be checked by disconnecting the PP line between the OBC and the vehicle charging port and measuring the change in resistance between the PP line (on the vehicle charging port side of the connector) and the vehicle chassis earth.
To complete this test you may need to disconnect connections at the OBC end of the circuit or locate a more accessible connector using the manufacturer's technical information.
In all circumstances, do not carry out a resistance measurement with the Proximity Pilot line intact as there is the potential for harm to the vehicle or your test equipment.
The modes of PP line operation for each connection status are described as follows:
- With the EVSE charging cable and vehicle disconnected, the PP line circuit comprises a single path to chassis earth via a 2.7 kilohm resistor in the vehicle charging port, hence the measured resistance is 2.7 kilohms.
- With the EVSE charging cable and vehicle connected, an additional path to chassis earth is created and the PP line circuit becomes two parallel paths to earth, with one path having a resistance of 150 ohms and the other 2.7 kilohms. The total resistance of the parallel circuit is 1/(1/150 + 1/2700) ohms = 142 ohms.
- With the EVSE charging cable and vehicle connected and the Type 1 connector button depressed, the path to chassis earth is again two parallel paths to earth but with one path having a total resistance of 480 ohms (150 ohms + 330 ohms) and the other 2.7 kilohms. The total resistance of the new parallel circuit is 1/(1/480 + 1/2700) ohms = 408 ohms.
Symptoms and fault diagnosis
If the charging does not start when the EVSE charging cable is connected to the vehicle, there may be a high resistance in the PP line circuit within the charging cable connector. This is because the OBC expects to see approximately 142 ohms on this line before it commands, via a separate circuit, the EVSE to start charging.
