Code
B2804
HYUNDAI
B — Body
No Response NM Message (IPM/DATC)
Views:
UK: 18
EN: 22
RU: 23
AI status
Completed
Completed
100%
Causes
- Open or short in CAN / wiring between modules
- Faulty connector or poor pin contact at IPM, DATC, BCM or harness junction
- Blown fuse or loss of module supply/ground
- Faulty IPM or DATC module (internal transceiver or processor)
- Other module on the same bus pulling the network down
- Intermittent battery/low system voltage or parasitic draw
Symptoms
- Climate control (DATC) not responding or inoperative
- IPM-controlled functions (lamps, power distribution) may not operate correctly
- Communication-related DTCs present for other modules
- Intermittent or complete loss of certain body functions
- Potential warning lamps or messages related to vehicle network
What to check
- Use a capable scan tool to read stored/freeze-frame codes and attempt to communicate with IPM and DATC
- Verify battery voltage (12V nominal, >12.2V with engine off) and system grounds
- Check fuses and fusible links supplying IPM/DATC
- Visually inspect connectors and harnesses for damage, corrosion, or water intrusion
- Use bus diagnostics to confirm presence or absence of NM messages on the CAN network
- Measure CAN_H and CAN_L voltages and check for shorts to battery or ground
Signal parameters
- CAN bus idle voltages: CAN_H ~2.5V (nominal 2.5–3.5V), CAN_L ~2.5V (nominal ~1.5–2.5V); differential ~0V (recessive) and ~2V (dominant) — verify with manufacturer specs
- Network Management (NM) messages: periodic messages when ignition on and wake/sleep messages during key cycles — exact cadence varies by model (refer to OEM data)
- Expected module responses: IPM/DATC should appear in module list on OEM scanner and respond to diagnostic requests
Diagnostic algorithm
- Confirm code presence and note when it is set (ignition state, after sleep, while running).
- Attempt communication with IPM and DATC using a factory-level or equivalent scan tool. If neither responds, suspect bus or module power/ground.
- Check battery voltage and main ground points. Replace/repair if low or intermittent.
- Inspect fuses and power feeds to IPM/DATC; restore any missing supplies.
- Visually inspect connectors and harnesses at the IPM, DATC, BCM and common junctions; repair or reseat as needed.
- With ignition on, use a scope or quality multimeter to check CAN_H/CAN_L at the modules for proper idle voltages and signal activity. Look for shorts to 12V or ground.
- Use a bus analyzer/scan tool to observe message traffic and confirm absence of NM messages from IPM/DATC. If other modules are also missing, focus on bus integrity and termination.
- Isolate by disconnecting suspect modules one at a time (if safe) to see if bus behavior changes; watch for bus restoration or new faults.
- If wiring and power/ground are good but the module still does not transmit NM messages, replace or reflash the module per OEM procedure.
- After repairs, clear codes, cycle ignition, and verify successful communication and that the DTC does not return on road/test cycles.
Likely causes
- Damaged/crimped/loose CAN wiring near IPM or DATC
- Corroded connector terminals at IPM or DATC
- Blown fuse supplying the module or its transceiver
- Failed module CAN transceiver in IPM or DATC
- Short to ground or power on CAN_H or CAN_L from another device
Fault status
Status
No Response NM Message (IPM/DATC) — the expected Network Management message from the Integrated Power Module or DATC was not received. Indicates loss of communication from the listed module(s) on the vehicle network.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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