All codes
Service call
SC490
High-voltage power / bias leak
BTransfer / HV
Level B — stop, power-cycle may clear
First check
Which other SC is in history? Chase that unit first, then HVPS.
What it means
HVPS detected a leak or failed to produce bias. Catch-all that often rides with 302/401/441.
Likely causes
- HVPS
- Leak at PCU/ITB contact
- Moisture
On-site steps
Parts to have on the truck
- HVPS
- PCU
- ITB
Related codes
Confirm the subcode and part number in the FSM for this serial. Raicoh is a field companion, not a replacement for the book.