Code
B280300
HYUNDAI
B — Body
No Response NM Message (AMP) | Timeout Multimedia CAN Message (AMP)
Views:
UK: 14
EN: 19
RU: 14
AI status
Completed
Completed
100%
Causes
- AMPLIFIER (AMP) power or ground fault
- Damaged or loose connector at AMP
- Open or short in multimedia CAN wiring (CAN H / CAN L)
- Missing/misaligned CAN termination (high resistance)
- AMP module internal failure (CAN transceiver or MCU)
- Other module on the multimedia bus causing bus-off or noise
Symptoms
- No audio output from amplifier / no sound from speakers
- Multimedia system features partially or completely inoperative
- Radio/head unit displays communication or module missing warnings
- One or more communication-related DTCs stored
- Intermittent audio or loss of amplifier power
- Possible battery drain if module repeatedly attempts wakeup
What to check
- Read all stored and pending DTCs on all control modules; record freeze frames and occurrence counters
- Verify battery voltage (12.6V+ static, >11.5V cranking/wake tests) and check related fuses and relays for the AMP
- Visually inspect AMP connector and harness for corrosion, damage, water ingress or bent pins
- Check CAN H/L wiring for continuity and shorts to B+ or ground
- Measure termination resistance across CAN H and CAN L (approx. 60 ohms with ignition ON)
- Use a scan tool or oscilloscope to verify CAN traffic and NM frames reach the AMP connector
Signal parameters
- CAN bus bit rate: vehicle-specific (common values 250 kbps or 500 kbps) — confirm with service data
- Idle voltages: CAN H ≈ 2.5V, CAN L ≈ 2.5V (recessive); dominant state CAN H ≈ 3.5V, CAN L ≈ 1.5V (approx.)
- Differential voltage dominant ≈ 2.0V (approx.)
- Termination resistance ≈ 60 ohms (two 120-ohm terminators in parallel)
- NM message cycle/wakeup interval and timeout value: vehicle-specific (check service manual for AMP NM timeout)
- Typical DLC/IDs: multimedia-specific message IDs — check OEM message list for AMP ID and NM message
Diagnostic algorithm
- Verify and record stored DTCs from relevant modules (AVN, BCM, AMP). Clear codes and attempt to reproduce.
- Check battery voltage and related fuses/power feeds to the AMP (inspect ignition-switched and constant supplies). Repair any power issues.
- Visually inspect AMP connectors and harness. Repair any damage, clean corrosion, and ensure proper mating.
- Measure resistance between CAN H and CAN L with ignition ON; expect ~60 ohms. If abnormal, isolate sections of wiring to find open/short.
- Using a scan tool, monitor CAN bus traffic and look for NM frames from head unit and responses. Confirm whether AMP appears on bus.
- Probe CAN H and CAN L at the AMP connector with oscilloscope: verify healthy differential signals, message activity, and absence of excessive noise.
- If bus is silent at AMP but active elsewhere, check wiring between AMP and nearest junction/module for open/short. Repair as needed.
- If bus shows errors or module is in bus-off state, attempt to reset module (battery disconnect or module reset procedure) then recheck. If AMP remains unresponsive, suspect internal AMP failure.
- Check for required software updates or reprogramming. Reflash or update modules per OEM procedure if recommended.
- If wiring and bus are confirmed good and software current, replace AMP module and verify communication and function. Clear codes and road-test/reproduce.
Likely causes
- Blown fuse or poor battery/ignition supply to the AMP
- Corroded connector or pinback at the AMP harness
- CAN network wiring shorted to power/ground or open circuit
- Failed AMP CAN transceiver or module gone into bus-off
- Faulty termination resistor or missing termination due to disconnected module
Fault status
Status
No response to Network Management (NM) messages from AMP on the multimedia CAN network — communication timeout detected.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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