Powertrain, generic · Hybrid propulsion

P0B33 High Voltage Service Disconnect Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The high-voltage service disconnect is the removable plug, usually fused, that splits the traction battery for safe servicing. A low-voltage detection loop runs through the plug, and the battery controller reads it to know whether the plug is seated; patents from Ford and Lear describe this loop, which opens before the main contacts part. P0B33 is the general circuit code for this detection input. No manufacturer documents P0B33 publicly. CARB requires such hybrid components to be monitored like any input. Performance, low, high and open have their own codes, P0B34 to P0B37; the separate high-voltage interlock loop uses P0A0A ff. Expect contactors to stay open: no ready mode, no charging.

Likely causes

Service disconnect plug not fully seated or locked after service
Chafed, open or shorted detection loop wiring between plug base and battery controller
Corroded or spread terminals in the plug or its base
Battery controller input fault

Symptoms

  • Vehicle does not enter ready mode or will not start
  • High-voltage system warning and MIL on
  • Charging not possible

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€80–1,500
Time0.5–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

hv service disconnect switchwiring harnessbms

Related codes

P0B34P0B35P0B36P0B37P0A0A

References: law.cornell.edu, patents.google.com, patents.google.com.