Service disconnect plug not fully seated or latched; Damaged or corroded terminals in the service disconnect circuit; Open or shorted wiring in the service disconnect detection circuit; Faulty service disconnect switch or interlock mechanism; Failed high-voltage battery pack assembly (internal disconnect fault); Corrosion or water intrusion in the service disconnect connector; Control module software error or internal fault in the battery energy control module

DTC codes / P0Bxx · Hybrid propulsion / P0B35

P0B35High Voltage Service Disconnect Circuit Low

Q: What does code P0B35 mean?

High Voltage Service Disconnect Circuit Low. P0B35 indicates that the high-voltage service disconnect circuit has been detected as having a low voltage condition when it should be at a higher level, typically when the service disconnect plug is removed or the interlock circuit is open. The computer monitors the voltage on the service disconnect detection circuit and sets this code when the voltage falls below the expected threshold, signaling a potential safety issue with the high-voltage system.

P0B35 indicates that the high-voltage service disconnect circuit has been detected as having a low voltage condition when it should be at a higher level, typically when the service disconnect plug is removed or the interlock circuit is open. The computer monitors the voltage on the service disconnect detection circuit and sets this code when the voltage falls below the expected threshold, signaling a potential safety issue with the high-voltage system.

SystemPowertrain

Code typeGeneric (all makes)

SeverityHigh

Fix difficultyProfessional

AreaHybrid propulsion

Symptoms you may notice

High-voltage system warning light illuminated on the dashboard
Vehicle may fail to start or enter ready mode
Reduced power or complete shutdown of hybrid/electric propulsion
Service disconnect plug may appear loose or improperly seated
Often no symptoms besides the warning light if the fault is intermittent
Possible inability to charge the high-voltage battery

Common causes, most likely first

Service disconnect plug not fully seated or latched
Damaged or corroded terminals in the service disconnect circuit
Open or shorted wiring in the service disconnect detection circuit
Faulty service disconnect switch or interlock mechanism
Failed high-voltage battery pack assembly (internal disconnect fault)
Corrosion or water intrusion in the service disconnect connector
Control module software error or internal fault in the battery energy control module

How to diagnose and fix it

Verify the service disconnect plug is fully inserted and the locking mechanism is engaged
Inspect the service disconnect connector and terminals for corrosion, damage, or loose pins
Check the service disconnect circuit wiring for continuity and shorts using a multimeter
Test the service disconnect switch for proper open/closed continuity
Inspect the high-voltage battery pack for internal disconnect faults or damaged components
Reprogram or update the battery energy control module if applicable
Replace the service disconnect plug, switch, or high-voltage battery pack as needed

Service disconnect plug often the culprit

A service disconnect plug that is not fully latched is the most common cause of this code, and simply reseating it can resolve the issue without any parts replacement.
The code can set intermittently due to vibration or temperature changes affecting a marginal connection, so a wiggle test of the connector while monitoring live data can reveal the fault.
Technicians sometimes overlook the service disconnect interlock circuit when diagnosing no-start conditions, focusing instead on the high-voltage battery itself.
This code does not always indicate a failed high-voltage battery; the fault may lie in the low-voltage detection circuit or the service disconnect switch.
After any repair involving the service disconnect, the high-voltage system must be properly reinitialized and the code cleared to confirm the fix.

Can I keep driving with P0B35?

Do not drive the vehicle with this code present, as the high-voltage system may be disabled or in a unsafe state. Have the vehicle inspected by a qualified high-voltage technician before attempting to drive.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.