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Home / DTC / U0135 — Lost Communication With Differential Control Module Front

U0135 — Lost Communication With Differential Control Module Front

Detailed page for trouble code U0135.

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Code

U0135

HYUNDAI U — Network/User

Lost Communication With Differential Control Module Front

Brand: HYUNDAI
Type: U — Network/User
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or short in CAN bus wiring (CAN High/CAN Low) to the front differential module
  • Corroded, loose or damaged connector at the front differential control module
  • Blown fuse or loss of module power or ground
  • Faulty front differential control module (module internal failure)
  • Faulty gateway/BCM/ECU that routes CAN messages
  • Water intrusion or physical damage to wiring harness or module

Symptoms

  • Malfunction Indicator Lamp (MIL) or multiple network warning lights illuminated (ABS, AWD/4WD, ESC)
  • Front differential / AWD functions disabled or forced to limp mode
  • No data for front differential module on a scan tool (module missing from network list)
  • Unexpected vehicle behavior during cornering or traction control events
  • Related diagnostic trouble codes present in other modules

What to check

  • Verify battery voltage is within specification (12V nominal) before testing electronics
  • Use a scan tool to confirm U0135 and list other network modules present/missing
  • Check for related DTCs in ABS, BCM, TCM, and instrument cluster
  • Inspect fuses and power distribution for front differential control module circuit
  • Visually inspect front differential module connector and wiring for damage, corrosion, or water intrusion
  • Perform a wiggle test on harness while observing network status/messages with a scan tool

Signal parameters

  • CAN_H idle voltage approx. 2.5–2.75 V (key on, bus idle)
  • CAN_L idle voltage approx. 2.25–2.5 V (key on, bus idle)
  • Dominant state: CAN_H ~3.5 V, CAN_L ~1.5 V (differential ~1.5–2.0 V)
  • Termination resistance CAN_H–CAN_L ≈ 60 ohms (two 120Ω terminators in parallel)
  • Module supply voltage (VBATT) ≈ 11–14 V with ignition on
  • Module ground resistance to chassis < 1 Ω

Diagnostic algorithm

  1. Connect a capable scan tool and confirm U0135 and any additional network DTCs; note freeze frame and time of occurrence.
  2. Verify battery voltage and inspect/replace any blown fuses related to the front differential module power circuit.
  3. Visually inspect the front differential control module connector and harness for corrosion, bent pins, moisture, or damage; repair or clean as needed.
  4. With ignition ON, check for presence of the front differential module on the vehicle network list; if missing, attempt to communicate while monitoring CAN traffic.
  5. Probe and record CAN_H and CAN_L voltages at the module connector and at the nearest gateway/BCM; compare values to expected idle and dominant states.
  6. Measure CAN termination resistance between CAN_H and CAN_L at the module harness (expect ≈60 Ω). If open or far from expected, trace to missing/failed terminators.
  7. Perform continuity checks for CAN_H and CAN_L from the front differential connector back to gateway/BCM; look for shorts to battery or ground and open circuits.
  8. Check module supply and ground circuits for proper voltage and low resistance ground; repair any high resistance connections.
  9. If wiring and network integrity are confirmed, try re-seating the module connector and clear codes, then attempt to communicate again.
  10. If intermittent communications persist, perform wiggle testing and load testing; use an oscilloscope to view CAN waveform quality for reflections, noise, or missing edges.
  11. If all harness and network tests pass and the module still will not communicate, consider module replacement or reprogramming per manufacturer procedures.
  12. After repair, clear codes and perform a road test and full network scan to confirm normal communications and that no additional DTCs return.

Likely causes

  • Loose or corroded connector at front differential control module
  • Broken or pinched CAN wires between the front differential module and gateway/BCM
  • Blown supply fuse or bad ground at the module
  • Failed front differential control module
  • Intermittent wiring fault (chafing, corrosion) causing intermittent comms

Fault status

⚠️ Status
Lost Communication With Differential Control Module Front — front differential module not responding on CAN network; vehicle network messages to/from module absent or intermittent.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-3.0 hours

Similar codes

U0100 U0121 U0136 U0140 U0155
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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