Code
U1002
HYUNDAI
U — Network/User
Microphone 1 shortcut | Lost Communication with ECM (H-CAN)
Views:
UK: 9
EN: 21
RU: 16
AI status
Completed
Completed
100%
Causes
- Open or short in Microphone 1 wiring harness
- Corroded/loose connector at microphone, audio unit, or ECM
- Faulty microphone/module (audio/voice control unit) on H‑CAN
- ECM or other CAN node internal failure
- Missing or damaged CAN bus termination resistor
- Low battery voltage, poor ground or power supply interruption
Symptoms
- Voice recognition, hands‑free or microphone audio unavailable or intermittent
- H‑CAN network errors or multiple communication DTCs present
- Inability to communicate with ECM or other modules using a scan tool
- Related modules display faults or reduced functionality
- Possible engine management symptoms if ECM communication is lost (rare)
What to check
- Retrieve all stored and pending U‑codes and freeze frame data with a capable scan tool
- Check for other network-related codes (U1000, U0100, U0073, etc.)
- Visually inspect microphone, audio unit, ECM connectors and wiring for damage, corrosion, or water intrusion
- Verify battery voltage and good chassis/engine ground connections
- Check fuses and power feeds for microphone/audio module and ECM
- Perform wiggle test of harnesses while monitoring communication status
Signal parameters
- H‑CAN idle (recessive) voltage ~2.5 V on CAN_H and CAN_L (verify with service data)
- Dominant state: CAN_H and CAN_L move toward ~3.5 V / ~1.5 V respectively (measure with scope)
- Bus differential voltage nominal ~2.0 V when dominant; near 0 V when recessive (verify with oscilloscope)
- Termination resistance ~60 ohms across CAN_H and CAN_L (measure with power off)
- Microphone circuit: expected supply/bias and continuity per vehicle service manual (check for shorts to ground/12 V)
Diagnostic algorithm
- Connect a professional scan tool supporting H‑CAN; record all network codes and module presence. Clear codes and attempt to reproduce.
- Check battery voltage (>=12.4 V) and main grounds; recharge or repair as needed. Retest network communication.
- Visually inspect microphone, audio unit and ECM connectors and wiring for damage, corrosion, or water entry. Repair as needed.
- With ignition on, measure CAN_H and CAN_L voltages at a convenient connector. Compare to expected values and check for stuck dominant state.
- Use an oscilloscope to view CAN bus signals while scanning for active messages. Look for noise, missing frames, or a node holding the bus dominant.
- Measure termination resistance between CAN_H and CAN_L with vehicle power off; expect ~60 ohms (two 120Ω in parallel).
- Disconnect suspected microphone/audio module and observe whether the U1002 clears or H‑CAN communication returns — if disconnecting a node restores the bus, inspect/replace that module or its wiring.
- If the microphone and wiring check good, verify ECM CAN transceiver operation and power feeds; consult OEM service manual for ECM bench tests or replacement procedures.
- If no wiring or module faults are found, check for software updates or TSBs; perform module reprogramming only per OEM procedures.
- After repair, clear codes and verify normal operation and absence of intermittent communication errors.
Likely causes
- Damaged microphone harness shorted to ground or battery
- Connector corrosion or bent pins at microphone or audio unit
- Failed microphone/voice control module that pulls the bus off
- Faulty ECM or its CAN transceiver
- Open or incorrect termination resistor on H‑CAN
Fault status
Status
Lost communication with ECM on H‑CAN related to Microphone 1 (Microphone 1 short/open or network fault).
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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Code
U1002
LAND ROVER
U — Network/User
switchpack - circuit indicator status
Views:
UK: 3
EN: 10
RU: 6
AI status
Completed
Completed
100%
Causes
- Open or short in Microphone 1 wiring harness
- Corroded/loose connector at microphone, audio unit, or ECM
- Faulty microphone/module (audio/voice control unit) on H‑CAN
- ECM or other CAN node internal failure
- Missing or damaged CAN bus termination resistor
- Low battery voltage, poor ground or power supply interruption
Symptoms
- Voice recognition, hands‑free or microphone audio unavailable or intermittent
- H‑CAN network errors or multiple communication DTCs present
- Inability to communicate with ECM or other modules using a scan tool
- Related modules display faults or reduced functionality
- Possible engine management symptoms if ECM communication is lost (rare)
What to check
- Retrieve all stored and pending U‑codes and freeze frame data with a capable scan tool
- Check for other network-related codes (U1000, U0100, U0073, etc.)
- Visually inspect microphone, audio unit, ECM connectors and wiring for damage, corrosion, or water intrusion
- Verify battery voltage and good chassis/engine ground connections
- Check fuses and power feeds for microphone/audio module and ECM
- Perform wiggle test of harnesses while monitoring communication status
Signal parameters
- H‑CAN idle (recessive) voltage ~2.5 V on CAN_H and CAN_L (verify with service data)
- Dominant state: CAN_H and CAN_L move toward ~3.5 V / ~1.5 V respectively (measure with scope)
- Bus differential voltage nominal ~2.0 V when dominant; near 0 V when recessive (verify with oscilloscope)
- Termination resistance ~60 ohms across CAN_H and CAN_L (measure with power off)
- Microphone circuit: expected supply/bias and continuity per vehicle service manual (check for shorts to ground/12 V)
Diagnostic algorithm
- Connect a professional scan tool supporting H‑CAN; record all network codes and module presence. Clear codes and attempt to reproduce.
- Check battery voltage (>=12.4 V) and main grounds; recharge or repair as needed. Retest network communication.
- Visually inspect microphone, audio unit and ECM connectors and wiring for damage, corrosion, or water entry. Repair as needed.
- With ignition on, measure CAN_H and CAN_L voltages at a convenient connector. Compare to expected values and check for stuck dominant state.
- Use an oscilloscope to view CAN bus signals while scanning for active messages. Look for noise, missing frames, or a node holding the bus dominant.
- Measure termination resistance between CAN_H and CAN_L with vehicle power off; expect ~60 ohms (two 120Ω in parallel).
- Disconnect suspected microphone/audio module and observe whether the U1002 clears or H‑CAN communication returns — if disconnecting a node restores the bus, inspect/replace that module or its wiring.
- If the microphone and wiring check good, verify ECM CAN transceiver operation and power feeds; consult OEM service manual for ECM bench tests or replacement procedures.
- If no wiring or module faults are found, check for software updates or TSBs; perform module reprogramming only per OEM procedures.
- After repair, clear codes and verify normal operation and absence of intermittent communication errors.
Likely causes
- Damaged microphone harness shorted to ground or battery
- Connector corrosion or bent pins at microphone or audio unit
- Failed microphone/voice control module that pulls the bus off
- Faulty ECM or its CAN transceiver
- Open or incorrect termination resistor on H‑CAN
Fault status
Status
Lost communication with ECM on H‑CAN related to Microphone 1 (Microphone 1 short/open or network fault).
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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Code
U1002
Other
U — Network/User
SCP (J1850) Invalid or Missing Data for Primary Id
Views:
UK: 13
EN: 33
RU: 21
AI status
Completed
Completed
100%
Causes
- Open or short in Microphone 1 wiring harness
- Corroded/loose connector at microphone, audio unit, or ECM
- Faulty microphone/module (audio/voice control unit) on H‑CAN
- ECM or other CAN node internal failure
- Missing or damaged CAN bus termination resistor
- Low battery voltage, poor ground or power supply interruption
Symptoms
- Voice recognition, hands‑free or microphone audio unavailable or intermittent
- H‑CAN network errors or multiple communication DTCs present
- Inability to communicate with ECM or other modules using a scan tool
- Related modules display faults or reduced functionality
- Possible engine management symptoms if ECM communication is lost (rare)
What to check
- Retrieve all stored and pending U‑codes and freeze frame data with a capable scan tool
- Check for other network-related codes (U1000, U0100, U0073, etc.)
- Visually inspect microphone, audio unit, ECM connectors and wiring for damage, corrosion, or water intrusion
- Verify battery voltage and good chassis/engine ground connections
- Check fuses and power feeds for microphone/audio module and ECM
- Perform wiggle test of harnesses while monitoring communication status
Signal parameters
- H‑CAN idle (recessive) voltage ~2.5 V on CAN_H and CAN_L (verify with service data)
- Dominant state: CAN_H and CAN_L move toward ~3.5 V / ~1.5 V respectively (measure with scope)
- Bus differential voltage nominal ~2.0 V when dominant; near 0 V when recessive (verify with oscilloscope)
- Termination resistance ~60 ohms across CAN_H and CAN_L (measure with power off)
- Microphone circuit: expected supply/bias and continuity per vehicle service manual (check for shorts to ground/12 V)
Diagnostic algorithm
- Connect a professional scan tool supporting H‑CAN; record all network codes and module presence. Clear codes and attempt to reproduce.
- Check battery voltage (>=12.4 V) and main grounds; recharge or repair as needed. Retest network communication.
- Visually inspect microphone, audio unit and ECM connectors and wiring for damage, corrosion, or water entry. Repair as needed.
- With ignition on, measure CAN_H and CAN_L voltages at a convenient connector. Compare to expected values and check for stuck dominant state.
- Use an oscilloscope to view CAN bus signals while scanning for active messages. Look for noise, missing frames, or a node holding the bus dominant.
- Measure termination resistance between CAN_H and CAN_L with vehicle power off; expect ~60 ohms (two 120Ω in parallel).
- Disconnect suspected microphone/audio module and observe whether the U1002 clears or H‑CAN communication returns — if disconnecting a node restores the bus, inspect/replace that module or its wiring.
- If the microphone and wiring check good, verify ECM CAN transceiver operation and power feeds; consult OEM service manual for ECM bench tests or replacement procedures.
- If no wiring or module faults are found, check for software updates or TSBs; perform module reprogramming only per OEM procedures.
- After repair, clear codes and verify normal operation and absence of intermittent communication errors.
Likely causes
- Damaged microphone harness shorted to ground or battery
- Connector corrosion or bent pins at microphone or audio unit
- Failed microphone/voice control module that pulls the bus off
- Faulty ECM or its CAN transceiver
- Open or incorrect termination resistor on H‑CAN
Fault status
Status
Lost communication with ECM on H‑CAN related to Microphone 1 (Microphone 1 short/open or network fault).
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email