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Home / DTC / U1970 — Multimedia CAN Bus Off Error

U1970 — Multimedia CAN Bus Off Error

Detailed page for trouble code U1970.

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U1970

HYUNDAI U — Network/User

Multimedia CAN Bus Off Error

Brand: HYUNDAI
Type: U — Network/User
AI status
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Page language: EN

Causes

  • Damaged or shorted CAN-H/CAN-L wiring (open, short to ground, short to battery).
  • Poor or corroded connector or ground at multimedia module or CAN harness.
  • Failed multimedia control module (internal transceiver or processor fault).
  • Another control module on the same CAN bus driving the line and forcing a bus-off condition.
  • Missing or incorrect termination (open or shorted 120 Ω resistor pair).
  • Low or unstable battery voltage or poor battery/charging system affecting CAN transceiver.

Symptoms

  • Multimedia functions (radio, display, navigation, Bluetooth) partially or completely inoperative.
  • No CAN messages from multimedia module when monitored with a scan tool.
  • Other modules that rely on multimedia data may show errors or reduced functionality.
  • Diagnostic trouble codes stored (U1970 plus possibly other U-codes).
  • Possible repeated appearance of CAN bus error or bus-off status after clearing codes.

What to check

  • Read and record all U- and B- codes from all modules with a capable scan tool.
  • Visually inspect CAN wiring, connectors, and multimedia module grounds for damage, corrosion, or looseness.
  • Measure battery voltage and charging system; ensure stable 12 V supply during testing.
  • Measure CAN_H and CAN_L voltages (idle/recessive ~2.5 V, dominant pulls one line down/up).
  • Check termination resistance across CAN_H and CAN_L at multiple locations (expected ~60 Ω total for two 120 Ω resistors in parallel).
  • Disconnect multimedia module from CAN bus and re-check bus health (message traffic and voltages).

Signal parameters

  • CAN_H idle ≈ 2.5 V (0.5 V swing on dominant bits), CAN_L idle ≈ 2.5 V; differential recessive ≈ 0 V, dominant differential ≈ ±2 V.
  • Bus bit rate (vehicle dependent) commonly 500 kb/s or 250 kb/s; message frequency for multimedia messages depends on function.
  • Measured termination resistance across CAN_H/CAN_L ≈ 60 Ω (two 120 Ω resistors in parallel).
  • Node error counters (if available) and bus-off flag reported by scan tool.
  • Number of transmitted/received frames per second for multimedia node (should be consistent with other vehicles of same model).

Diagnostic algorithm

  1. Record freeze frame and all related trouble codes from all modules. Note when U1970 sets (ignition state, startup, after driving).
  2. Visually inspect multimedia module connector, CAN harness routing, and all chassis/body grounds for damage and corrosion.
  3. With ignition ON (engine off acceptable), use a scan tool to monitor CAN traffic. Confirm whether the multimedia module appears on the bus or is silent/bus-off.
  4. Measure CAN_H and CAN_L voltages at the multimedia connector and at a known-good point on the same bus. Compare to expected idle voltages (~2.5 V).
  5. Measure the termination resistance across CAN_H and CAN_L at the bus; replace or repair if resistance is outside specification (~60 Ω).
  6. Check for short circuits: isolate segments and test for short to ground or battery on CAN_H/CAN_L. Wiggle harnesses to reproduce intermittent faults.
  7. Disconnect the multimedia module from the bus and re-check bus health. If bus returns to normal, the multimedia unit or its local wiring is likely at fault.
  8. If another module is suspected of causing bus-off, disconnect other modules or partition the bus per manufacturer procedure to locate the offending node.
  9. If wiring and termination are good, inspect and test the multimedia module for failed CAN transceiver or internal faults; consider ECU reflash or replacement per Hyundai service guidance.
  10. After repairs, clear codes and road-test to confirm the issue is resolved. Re-scan all modules for additional faults.

Likely causes

  • Intermittent or permanent short on CAN wiring near multimedia module.
  • Faulty CAN transceiver inside multimedia unit.
  • Loose or corroded connector at multimedia harness or ground point.
  • Failed module elsewhere on the CAN bus creating communication errors.

Fault status

⚠️ Status
Multimedia CAN Bus Off — multimedia control module reports CAN bus is in a bus-off state or lost CAN communication.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

Similar codes

U0073 U0100 U0140 U0121
371

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

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