U3545 is a manufacturer-specific code indicating the powertrain control module has detected an abnormal electrical state in the high-voltage interlock circuit path “P.” The interlock is a safety loop that must remain closed and intact for the high-voltage system to operate; this code means the module sees an open, short, or incorrect resistance in that monitored segment.
The most common cause is a connector on the high-voltage loop that is not fully latched, a missing or damaged shorting bar, or a connector position assurance lock not seated, causing the interlock path to open.
The dedicated low-voltage interlock wires can break, pinch, rub through insulation, or corrode at pass-throughs, producing an open circuit or short to ground/power that the control module detects.
Loose, backed-out, spread, or oxidized pins in the interlock connector create intermittent or permanent resistance changes that the module reads as a circuit fault.
After service, the high-voltage service disconnect or a sealing cover may be inserted but not fully locked, breaking the interlock loop for circuit P.
A battery pack, inverter, converter, compressor, or heater module can have an internal interlock switch or trace failure that opens the loop even though external wiring appears normal.
Only after the wiring, connectors, and all high-voltage components are verified should a control-module input fault be considered, because module failure is an uncommon cause of this code.
It is usually not safe or permitted by the vehicle’s failsafes. The high-voltage system is typically disabled, which can cause loss of propulsion or a no-start condition.
Clearing the code will not repair an open interlock loop. The fault will generally return immediately and the vehicle will remain in a protective mode.
Not usually. This code points to the safety interlock circuit, and the most common causes are connectors, wiring, or service-disconnect seating rather than the battery itself.
Usually no. This code is almost always caused by wiring, connector, or high-voltage component interlock faults. Control-module replacement is rarely the correct fix and should only be considered after the entire circuit is proven good.