Code
U029A
Generic
U — Network/User
Lost Communication With Hybrid/EV Battery Pack Sensor Module
Views:
UK: 15
EN: 41
RU: 26
AI status
Completed
Completed
100%
Causes
- Open or shorted communication bus (CAN/LIN) wiring
- Corroded or loose connector pins at the battery sensor module or gateway module
- Blown fuse, relay, or lost module power/ground to the sensor module
- Failed hybrid/EV battery pack sensor module or gateway/ECU
- Faulty termination resistor(s) or incorrect bus topology
- Intermittent wiring damage from chafing, heat, or water intrusion
Symptoms
- MIL/TPMS/dashboard warning indicating hybrid/EV battery or communication fault
- Loss of EV or hybrid drive mode or reduced power/“limp” mode
- Inaccurate or missing battery pack voltage/SOC/temperature data on driver display or HVAC control
- Other modules reporting related U-codes or CAN timeout errors
- Vehicle may refuse high-voltage charge or show charging errors
What to check
- Use a capable scan tool to read stored DTCs and freeze frame data; note related U-codes
- Check for additional module faults that indicate a network-wide issue
- Visually inspect battery pack sensor module connector, wiring harness, and nearby components for damage or corrosion
- Verify fuses and relays that supply the sensor module and gateway/ECU
- Check for proper module power and ground with a DVOM (reference vehicle wiring)
- Capture CAN bus traffic with a scan tool or oscilloscope to confirm the sensor module is not responding
Signal parameters
- CAN High idle voltage ~2.5 V (varies by vehicle)
- CAN Low idle voltage ~2.5 V (mirror of CAN H; dominant state changes ~1–2 V differential)
- Typical bus differential voltage during activity ~1–2 V
- CAN termination resistance ≈ 60 ohms (two 120 Ω in parallel) between CAN H and CAN L at key points
- Module supply voltage (12 V or vehicle-specified) present at sensor module power pin
- Ground resistance low (
Diagnostic algorithm
- Record freeze frame, full DTC list, and related network codes; do not erase yet.
- Clear the code and attempt to re-create the fault to confirm repeatability.
- Inspect battery pack sensor module connector and wiring for corrosion, water, damage, or loose pins; repair any physical damage.
- Verify fuses/relays and presence of correct supply voltage and ground at the sensor module with connector mated and ignition on.
- Using a scan tool, monitor live CAN messages for battery pack data; if no messages, use oscilloscope to check CAN H/L signals at the module connector and gateway/ECU.
- Measure termination resistance across CAN H-L; correct if out of spec (replace missing/bad terminators).
- If wiring/power OK but no communication, connect a known-good module or bench-test the sensor module if available, or try swapping gateway/relay module if supported by manufacturer guidance.
- Check for software updates or known module reprogramming procedures; perform reflash if required and authorized.
- After repairs, clear DTCs, complete a road test or operation cycle to confirm code does not return and all hybrid/EV functions behave normally.
- If fault persists and scope/scan indicate the module is not transmitting despite correct supplies, consider replacing the battery pack sensor module or refer to manufacturer-specific HV battery pack service procedures (observe high-voltage safety).
Likely causes
- Damaged CAN H/L wires near the battery pack (pinching, abrasion)
- Water intrusion or corrosion at the pack sensor connector
- Blown 12V/5V supply fuse or missing ground to the sensor module
- Failure of the battery pack sensor module electronics
- Failed gateway or ECU that relays battery pack messages to the network
- Open/shorted CAN termination resistor(s) or incorrect resistance across CAN H-L
Fault status
Status
Module reported timeout/no response from the hybrid/EV battery pack sensor module on the vehicle communication bus. Communication messages not received or invalid.
Repair difficulty: Hard
Diagnostic time: 2-6 hours
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Code
U029A
HYUNDAI
U — Network/User
Lost Communication With Hybrid Battery Pack Sensor Module
Views:
UK: 15
EN: 108
RU: 21
AI status
Completed
Completed
100%
Causes
- Open or shorted communication bus (CAN/LIN) wiring
- Corroded or loose connector pins at the battery sensor module or gateway module
- Blown fuse, relay, or lost module power/ground to the sensor module
- Failed hybrid/EV battery pack sensor module or gateway/ECU
- Faulty termination resistor(s) or incorrect bus topology
- Intermittent wiring damage from chafing, heat, or water intrusion
Symptoms
- MIL/TPMS/dashboard warning indicating hybrid/EV battery or communication fault
- Loss of EV or hybrid drive mode or reduced power/“limp” mode
- Inaccurate or missing battery pack voltage/SOC/temperature data on driver display or HVAC control
- Other modules reporting related U-codes or CAN timeout errors
- Vehicle may refuse high-voltage charge or show charging errors
What to check
- Use a capable scan tool to read stored DTCs and freeze frame data; note related U-codes
- Check for additional module faults that indicate a network-wide issue
- Visually inspect battery pack sensor module connector, wiring harness, and nearby components for damage or corrosion
- Verify fuses and relays that supply the sensor module and gateway/ECU
- Check for proper module power and ground with a DVOM (reference vehicle wiring)
- Capture CAN bus traffic with a scan tool or oscilloscope to confirm the sensor module is not responding
Signal parameters
- CAN High idle voltage ~2.5 V (varies by vehicle)
- CAN Low idle voltage ~2.5 V (mirror of CAN H; dominant state changes ~1–2 V differential)
- Typical bus differential voltage during activity ~1–2 V
- CAN termination resistance ≈ 60 ohms (two 120 Ω in parallel) between CAN H and CAN L at key points
- Module supply voltage (12 V or vehicle-specified) present at sensor module power pin
- Ground resistance low (
Diagnostic algorithm
- Record freeze frame, full DTC list, and related network codes; do not erase yet.
- Clear the code and attempt to re-create the fault to confirm repeatability.
- Inspect battery pack sensor module connector and wiring for corrosion, water, damage, or loose pins; repair any physical damage.
- Verify fuses/relays and presence of correct supply voltage and ground at the sensor module with connector mated and ignition on.
- Using a scan tool, monitor live CAN messages for battery pack data; if no messages, use oscilloscope to check CAN H/L signals at the module connector and gateway/ECU.
- Measure termination resistance across CAN H-L; correct if out of spec (replace missing/bad terminators).
- If wiring/power OK but no communication, connect a known-good module or bench-test the sensor module if available, or try swapping gateway/relay module if supported by manufacturer guidance.
- Check for software updates or known module reprogramming procedures; perform reflash if required and authorized.
- After repairs, clear DTCs, complete a road test or operation cycle to confirm code does not return and all hybrid/EV functions behave normally.
- If fault persists and scope/scan indicate the module is not transmitting despite correct supplies, consider replacing the battery pack sensor module or refer to manufacturer-specific HV battery pack service procedures (observe high-voltage safety).
Likely causes
- Damaged CAN H/L wires near the battery pack (pinching, abrasion)
- Water intrusion or corrosion at the pack sensor connector
- Blown 12V/5V supply fuse or missing ground to the sensor module
- Failure of the battery pack sensor module electronics
- Failed gateway or ECU that relays battery pack messages to the network
- Open/shorted CAN termination resistor(s) or incorrect resistance across CAN H-L
Fault status
Status
Module reported timeout/no response from the hybrid/EV battery pack sensor module on the vehicle communication bus. Communication messages not received or invalid.
Repair difficulty: Hard
Diagnostic time: 2-6 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
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👎 Dislike
0
Send to email