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Home / DTC / B2804 — No Response NM Message (IPM/DATC)

B2804 — No Response NM Message (IPM/DATC)

Detailed page for trouble code B2804.

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Code

B2804

HYUNDAI B — Body

No Response NM Message (IPM/DATC)

Brand: HYUNDAI
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

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

  1. Confirm code presence and note when it is set (ignition state, after sleep, while running).
  2. Attempt communication with IPM and DATC using a factory-level or equivalent scan tool. If neither responds, suspect bus or module power/ground.
  3. Check battery voltage and main ground points. Replace/repair if low or intermittent.
  4. Inspect fuses and power feeds to IPM/DATC; restore any missing supplies.
  5. Visually inspect connectors and harnesses at the IPM, DATC, BCM and common junctions; repair or reseat as needed.
  6. 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.
  7. 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.
  8. Isolate by disconnecting suspect modules one at a time (if safe) to see if bus behavior changes; watch for bus restoration or new faults.
  9. If wiring and power/ground are good but the module still does not transmit NM messages, replace or reflash the module per OEM procedure.
  10. 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

Similar codes

U0073 U0100 U0121 U0140 U0155
371

Browse 371 HYUNDAI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

HYUNDAI

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Code

B2804

LAND ROVER B — Body

Reservoir solenoid signal - short circuit to battery

Brand: LAND ROVER
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

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

  1. Confirm code presence and note when it is set (ignition state, after sleep, while running).
  2. Attempt communication with IPM and DATC using a factory-level or equivalent scan tool. If neither responds, suspect bus or module power/ground.
  3. Check battery voltage and main ground points. Replace/repair if low or intermittent.
  4. Inspect fuses and power feeds to IPM/DATC; restore any missing supplies.
  5. Visually inspect connectors and harnesses at the IPM, DATC, BCM and common junctions; repair or reseat as needed.
  6. 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.
  7. 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.
  8. Isolate by disconnecting suspect modules one at a time (if safe) to see if bus behavior changes; watch for bus restoration or new faults.
  9. If wiring and power/ground are good but the module still does not transmit NM messages, replace or reflash the module per OEM procedure.
  10. 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

Similar codes

U0073 U0100 U0121 U0140 U0155
320

Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LAND ROVER

Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

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