P0B59

Code

Generic P — Powertrain

Hybrid/EV Battery Voltage Sense G Circuit

Brand: Generic

Type: P — Powertrain

Views: UK: 34 EN: 46 RU: 38

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Page language: EN

Causes

Open or short in the Battery Voltage Sense G wiring harness
Corroded, loose, or damaged connector at the battery junction block or control module
Failed resistor divider or sense circuit hardware inside the battery junction/monitor assembly
Internal battery pack sensor/module fault
Blown fuse or faulty junction/fusible link feeding the sense circuit
Faulty hybrid/EV control module (ECU/BMS) or software/calibration error

Symptoms

Hybrid/EV warning light and battery system warning on the dash
HV system disabled or reduced power/limp mode
Inability to charge or reduced charge functionality
Incorrect battery pack voltage reading or inconsistent SOC indication
Possible loss of regenerative braking or altered drive behavior
DTC stored with possible related codes

What to check

Retrieve all stored/related DTCs and freeze frame data with a capable scan tool.
Verify manufacturer-specific safety procedures and isolate high-voltage system before any physical inspection.
Visual inspection of battery junction block, harness, and connectors for damage, corrosion, or loose terminals.
Check fuses/fusible links and any service-disconnects related to the battery sense circuits.
Measure sense circuit voltage at the control module pin and at the battery junction per service manual (key ON, HV system state as required).
Perform continuity and resistance checks on the sense wire between the ECU/BMS and the battery junction block.

Signal parameters

Sense circuit is typically a low-voltage scaled representation of pack voltage (ADC input): expected 0–5 V range at control module input.
Typical operating sense voltage (indicative): ~2.0–4.5 V depending on pack state and vehicle design (refer to vehicle service manual for exact scaling).
Fault thresholds (generic): open/low 5.0–5.5 V — consult manufacturer specs for precise limits.
Battery pack nominal HV range varies by vehicle (e.g., ~100–800 V depending on platform) — sense line is scaled down by resistor divider or signal conditioner.
BMS/ECU live data should show pack voltage and individual sense-channel ADC values for comparison.

Diagnostic algorithm

Read and record DTCs and freeze frame data using a compatible scan tool. Note any related codes (other sense channels, HV faults).
Follow manufacturer high-voltage safety procedures. Disable the HV system/service disconnect before touching battery hardware.
Perform a visual inspection of the battery pack junction block, sense harness, connector pins, and ground points. Look for damage, corrosion, water intrusion, rodent chews, or repair patches.
With the vehicle in the specified key/ready state per service manual, measure the sense circuit voltage at the ECU/BMS pin and at the battery junction block pin. Compare to expected values and to actual pack voltage measured at approved HV test points.
Check continuity and resistance of the sense wire(s) between the ECU and battery junction. Confirm no short to B+ or chassis ground (measure resistance to B+ and to ground).
Inspect and test related fuses, fusible links and service disconnects that feed the sensing hardware.
If wiring and connectors are good, test or replace the battery junction/sensor assembly or signal conditioner module per manufacturer procedure. Some packs require module-level testing or replacement.
If the sense circuit voltages are correct at the battery junction but not at the ECU/BMS, suspect harness damage between junction and ECU or the ECU input stage.
After repairs, clear codes and perform a full system test (charging, drive modes) and monitor live pack voltage and sense channel values. Confirm the DTC does not return under normal operation.
If the fault persists after harness and module checks, consider ECU/BMS internal failure and consult manufacturer diagnostics or service bulletin before replacement.

Likely causes

Broken or chafed sense wire causing open circuit
Sense wire shorted to battery positive (B+) or chassis ground
High resistance at crimp/terminal or corrosion at connector
Failed voltage divider/signal conditioner inside the battery harness or junction block
Intermittent connection from vibration or water ingress
BMS/ECU internal input failure

Fault status

⚠️ Status

Hybrid/EV Battery Voltage Sense G Circuit — abnormal or out-of-range voltage detected on the battery pack voltage sense G input. Possible open, short, high resistance, connector issue, sensor/module failure, or ECU input fault.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 1.5 - 4.0 hours