Code
B2957
HYUNDAI
B — Body
No Response NM Message (Clock)
Views:
UK: 11
EN: 17
RU: 14
AI status
Completed
Completed
100%
Causes
- Clock / instrument cluster module internal fault
- Open, short, or intermittent CAN or LIN bus wiring/connectors
- Faulty power or ground to the clock module (blown fuse, poor ground)
- Missing or incorrect network termination resistor(s)
- Low or unstable battery voltage
- Module not programmed/configured or corrupted software
Symptoms
- Clock display blank or inaccurate
- Instrument cluster partially or fully inoperative
- Communication-related warnings or trouble lights
- Modules fail to enter sleep or unexpected battery drain
- Other modules report lost communication with the clock/cluster
What to check
- Use a scan tool to read network status and confirm B2957 and any related U-codes
- Check battery voltage (should be ~12.4–12.8 V with ignition off, ~13.5–14.5 V with engine running)
- Inspect fuses and relays for the clock/cluster circuit
- Visually inspect clock/cluster connector for corrosion, bent pins, or water ingress
- Perform a wiring continuity/short test on CAN/LIN lines to the clock module
- Measure CAN High/Low voltages with key on (idle ~2.5 V on each) and check differential behavior when bus active
Signal parameters
- Expected NM message: periodic network management frame from clock/cluster (period depends on model; typically 100–1000 ms)
- CAN idle voltages: CANH ≈ 2.5 V, CANL ≈ 2.5 V; differential ≈ 0 V at idle
- CAN dominant state: CANH ≈ 3.5 V, CANL ≈ 1.5 V (differential ≈ 2.0 V) when transmitting
- LIN idle: near battery voltage when recessive; specific LIN waveform depends on node
- Termination resistance across CANH/CANL: ~60 ohms (two 120 ohm terminators in parallel)
- Battery voltage stable and within normal ranges during tests
Diagnostic algorithm
- Verify DTC and freeze frame with a capable diagnostic scanner; note any other communication codes (U-codes).
- Check battery state and connections; ensure ignition voltage is stable during testing.
- Inspect fuses/relays and the physical connector at the clock/cluster module for damage or corrosion.
- With ignition ON, monitor CAN (or LIN if applicable) signals at the clock module connector using a multimeter or scope to confirm idle voltages and activity.
- If no network activity at the module, trace wiring back toward the bus for opens/shorts; backprobing and continuity checks can locate breaks or shorts to ground/power.
- Check termination resistance on the CAN bus and verify there are two 120 ohm terminators (or vehicle-specific arrangement).
- Swap or test another known-good module (if available and permitted) or connect a known-good node to verify bus behavior.
- Disconnect suspected aftermarket devices and re-test communication.
- If wiring and bus integrity are confirmed, consider reflashing/reprogramming or replacing the clock/cluster module per manufacturer procedures.
- Clear codes and perform function test; monitor for recurrence and run battery drain/sleep tests if intermittent.
Likely causes
- Corroded connector or pin at the clock/cluster harness
- Blown fuse or poor ground feeding the clock module
- Damaged CAN/LIN wiring (chafing, pinched, rodent damage)
- Clock module failed or stuck and not sending NM frames
- Interference from recently installed aftermarket accessory
Fault status
Status
No Network Management (NM) message received from Clock module — communication timeout or missing NM frames.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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