CISPR-25 indicates that both CE-V and CE-I must be carried out to validate an automotive electronic device.
CE-V in dBuV is measured on B+ and GND lines using the LISN port.
CE-I in dBuA is measured using a “current probe” clamped at 5 cm, then at 75 cm from DUT’s connector. The probe is clamped on the whole harness, then on each connector separately. The RF noise measured may be coupled from DUT directly as well as from wire-to-wire along the 1.7 m test harness.
CISPR 25 is not very specific about supply lines CE “redundancy”, therefore we test everything for CE-I.
Chrysler is the only OEM that specifies in CS.00054 as exception from CISPR 25 to remove from “current probe” all Supply Lines (power and ground).
CS.00054 is asking to run CE-I on all wires not tested at CE-V, however measurements are aquired only at 5 cm from DUT's connector.
The EV does not mean the end of 12V automotive battery. For various safety reasons, complex modules are powered using two 13.5V / 200A batteries such that the Backup battery comes into play the moment the Main battery's voltage is outside operating voltage range.
The Ground Offset Test involves a voltage variation of +/- 1V on Supply Return line that may affect DUT circuitry referenced to an absolute 0V via remote ground. The diagram below shows how to use a combination of three power supplies to simulate the +/- 1V Ground Offset condition.