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U0404 — Invalid Data Received From Gear Shift Control Module A

Detailed page for trouble code U0404.

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Code

U0404

Generic U — Network/User

Invalid Data Received From Gear Shift Control Module A

AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Corroded/loose connector or damaged wiring to Gear Shift Control Module A
  • Faulty Gear Shift Control Module A (internal failure)
  • CAN bus electrical fault (short to battery/ground, open, high resistance)
  • Intermittent supply or ground to the GSCM A
  • Software mismatch or missing module configuration/coding after replacement
  • Multiple modules on the bus transmitting conflicting IDs or corrupted frames

Symptoms

  • MIL illuminated and U0404 stored in memory
  • Gear position indicator incorrect or blinking
  • Erratic or unavailable shift selection, harsh or limp-home shifting behavior in some cases
  • Network-related warnings (multiple U-codes) or other modules showing communication faults
  • Intermittent fault — may be present only at certain temperatures or after driving over bumps

What to check

  • Connect a capable scan tool and read freeze frame and all stored U-codes and network errors
  • Check live data: observe gear position message, message age, and update rate from GSCM A
  • Visually inspect connectors and harness for damage, corrosion, water ingress, or chafing near module and transmission
  • Measure battery voltage and check for stable supply while scanning (should be within spec, typically ~12.4–14.5 V)
  • With ignition on, measure CAN bus voltage: CAN_H ~2.5–3.5 V, CAN_L ~1.5–2.5 V; check bus idle voltages and differential
  • Check CAN bus termination resistance across CAN_H and CAN_L (approx. 60 ohms for two 120 ohm terminators in parallel)

Signal parameters

  • Expected message ID(s) from GSCM A (manufacturer specific) and periodicity (commonly 10–100 ms)
  • Message update rate / message age (should be steady; stale or missing indicates loss)
  • Payload length (bytes) and expected byte positions for gear position/shift status
  • Value ranges for gear position (e.g., Park/Reverse/Neutral/Drive coded values — should be within defined set)
  • Checksum/CRC present in message (if used) and whether checksum validates

Diagnostic algorithm

  1. Read and record all DTCs and freeze-frame data with a professional scan tool; clear codes and attempt to re-create.
  2. Check battery voltage and vehicle grounds for stability; repair any low or noisy supply issues.
  3. Inspect the GSCM A connector and wiring for corrosion, bent pins, water, or physical damage; repair or replace damaged sections.
  4. Verify CAN bus physical layer: measure idle voltages on CAN_H and CAN_L, and measure termination resistance (≈60 Ω). Repair shorts/opens as needed.
  5. Monitor live CAN messages: confirm GSCM A frames are present, at correct frequency, and with valid contents. Note message age and checksum status.
  6. Perform wiggle test along harness from module to main junctions while monitoring message integrity to find intermittent faults.
  7. If physical/CAN wiring checks good but data still invalid, attempt to reflash or update GSCM A software and ensure correct module coding/programming per manufacturer procedure.
  8. If module remains unresponsive or continues to send invalid data after wiring and software steps, replace GSCM A with a known-good unit and program/configure it to the vehicle. Re-test to verify.
  9. After repair, clear codes and perform a road test to confirm fault does not return; re-scan for any related network codes.

Likely causes

  • Corroded/crushed CAN connector at the GSCM A or pin corrosion
  • Short between CAN High and CAN Low, or short to battery/ground in harness near transmission
  • Failed GSCM A (water ingress, internal electronics fault)
  • Module replaced but not programmed/coded to vehicle CAN network
  • Poor ground at transmission or module mounting point causing data corruption

Fault status

⚠️ Status
Stored when the vehicle network receives malformed, corrupted, out-of-range, or missing data frames from Gear Shift Control Module A (invalid format, wrong values, failed checksum/CRC, or incorrect timing).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

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Code

U0404

HYUNDAI U — Network/User

Invalid Data Received From Gear Shift Control Module

AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Corroded/loose connector or damaged wiring to Gear Shift Control Module A
  • Faulty Gear Shift Control Module A (internal failure)
  • CAN bus electrical fault (short to battery/ground, open, high resistance)
  • Intermittent supply or ground to the GSCM A
  • Software mismatch or missing module configuration/coding after replacement
  • Multiple modules on the bus transmitting conflicting IDs or corrupted frames

Symptoms

  • MIL illuminated and U0404 stored in memory
  • Gear position indicator incorrect or blinking
  • Erratic or unavailable shift selection, harsh or limp-home shifting behavior in some cases
  • Network-related warnings (multiple U-codes) or other modules showing communication faults
  • Intermittent fault — may be present only at certain temperatures or after driving over bumps

What to check

  • Connect a capable scan tool and read freeze frame and all stored U-codes and network errors
  • Check live data: observe gear position message, message age, and update rate from GSCM A
  • Visually inspect connectors and harness for damage, corrosion, water ingress, or chafing near module and transmission
  • Measure battery voltage and check for stable supply while scanning (should be within spec, typically ~12.4–14.5 V)
  • With ignition on, measure CAN bus voltage: CAN_H ~2.5–3.5 V, CAN_L ~1.5–2.5 V; check bus idle voltages and differential
  • Check CAN bus termination resistance across CAN_H and CAN_L (approx. 60 ohms for two 120 ohm terminators in parallel)

Signal parameters

  • Expected message ID(s) from GSCM A (manufacturer specific) and periodicity (commonly 10–100 ms)
  • Message update rate / message age (should be steady; stale or missing indicates loss)
  • Payload length (bytes) and expected byte positions for gear position/shift status
  • Value ranges for gear position (e.g., Park/Reverse/Neutral/Drive coded values — should be within defined set)
  • Checksum/CRC present in message (if used) and whether checksum validates

Diagnostic algorithm

  1. Read and record all DTCs and freeze-frame data with a professional scan tool; clear codes and attempt to re-create.
  2. Check battery voltage and vehicle grounds for stability; repair any low or noisy supply issues.
  3. Inspect the GSCM A connector and wiring for corrosion, bent pins, water, or physical damage; repair or replace damaged sections.
  4. Verify CAN bus physical layer: measure idle voltages on CAN_H and CAN_L, and measure termination resistance (≈60 Ω). Repair shorts/opens as needed.
  5. Monitor live CAN messages: confirm GSCM A frames are present, at correct frequency, and with valid contents. Note message age and checksum status.
  6. Perform wiggle test along harness from module to main junctions while monitoring message integrity to find intermittent faults.
  7. If physical/CAN wiring checks good but data still invalid, attempt to reflash or update GSCM A software and ensure correct module coding/programming per manufacturer procedure.
  8. If module remains unresponsive or continues to send invalid data after wiring and software steps, replace GSCM A with a known-good unit and program/configure it to the vehicle. Re-test to verify.
  9. After repair, clear codes and perform a road test to confirm fault does not return; re-scan for any related network codes.

Likely causes

  • Corroded/crushed CAN connector at the GSCM A or pin corrosion
  • Short between CAN High and CAN Low, or short to battery/ground in harness near transmission
  • Failed GSCM A (water ingress, internal electronics fault)
  • Module replaced but not programmed/coded to vehicle CAN network
  • Poor ground at transmission or module mounting point causing data corruption

Fault status

⚠️ Status
Stored when the vehicle network receives malformed, corrupted, out-of-range, or missing data frames from Gear Shift Control Module A (invalid format, wrong values, failed checksum/CRC, or incorrect timing).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

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Code

U0404

LAND ROVER U — Network/User

Invalid data received from the gear control module

AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Corroded/loose connector or damaged wiring to Gear Shift Control Module A
  • Faulty Gear Shift Control Module A (internal failure)
  • CAN bus electrical fault (short to battery/ground, open, high resistance)
  • Intermittent supply or ground to the GSCM A
  • Software mismatch or missing module configuration/coding after replacement
  • Multiple modules on the bus transmitting conflicting IDs or corrupted frames

Symptoms

  • MIL illuminated and U0404 stored in memory
  • Gear position indicator incorrect or blinking
  • Erratic or unavailable shift selection, harsh or limp-home shifting behavior in some cases
  • Network-related warnings (multiple U-codes) or other modules showing communication faults
  • Intermittent fault — may be present only at certain temperatures or after driving over bumps

What to check

  • Connect a capable scan tool and read freeze frame and all stored U-codes and network errors
  • Check live data: observe gear position message, message age, and update rate from GSCM A
  • Visually inspect connectors and harness for damage, corrosion, water ingress, or chafing near module and transmission
  • Measure battery voltage and check for stable supply while scanning (should be within spec, typically ~12.4–14.5 V)
  • With ignition on, measure CAN bus voltage: CAN_H ~2.5–3.5 V, CAN_L ~1.5–2.5 V; check bus idle voltages and differential
  • Check CAN bus termination resistance across CAN_H and CAN_L (approx. 60 ohms for two 120 ohm terminators in parallel)

Signal parameters

  • Expected message ID(s) from GSCM A (manufacturer specific) and periodicity (commonly 10–100 ms)
  • Message update rate / message age (should be steady; stale or missing indicates loss)
  • Payload length (bytes) and expected byte positions for gear position/shift status
  • Value ranges for gear position (e.g., Park/Reverse/Neutral/Drive coded values — should be within defined set)
  • Checksum/CRC present in message (if used) and whether checksum validates

Diagnostic algorithm

  1. Read and record all DTCs and freeze-frame data with a professional scan tool; clear codes and attempt to re-create.
  2. Check battery voltage and vehicle grounds for stability; repair any low or noisy supply issues.
  3. Inspect the GSCM A connector and wiring for corrosion, bent pins, water, or physical damage; repair or replace damaged sections.
  4. Verify CAN bus physical layer: measure idle voltages on CAN_H and CAN_L, and measure termination resistance (≈60 Ω). Repair shorts/opens as needed.
  5. Monitor live CAN messages: confirm GSCM A frames are present, at correct frequency, and with valid contents. Note message age and checksum status.
  6. Perform wiggle test along harness from module to main junctions while monitoring message integrity to find intermittent faults.
  7. If physical/CAN wiring checks good but data still invalid, attempt to reflash or update GSCM A software and ensure correct module coding/programming per manufacturer procedure.
  8. If module remains unresponsive or continues to send invalid data after wiring and software steps, replace GSCM A with a known-good unit and program/configure it to the vehicle. Re-test to verify.
  9. After repair, clear codes and perform a road test to confirm fault does not return; re-scan for any related network codes.

Likely causes

  • Corroded/crushed CAN connector at the GSCM A or pin corrosion
  • Short between CAN High and CAN Low, or short to battery/ground in harness near transmission
  • Failed GSCM A (water ingress, internal electronics fault)
  • Module replaced but not programmed/coded to vehicle CAN network
  • Poor ground at transmission or module mounting point causing data corruption

Fault status

⚠️ Status
Stored when the vehicle network receives malformed, corrupted, out-of-range, or missing data frames from Gear Shift Control Module A (invalid format, wrong values, failed checksum/CRC, or incorrect timing).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

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