Code
U3010
HYUNDAI
U — Network/User
Ignition Input Start
Views:
UK: 9
EN: 19
RU: 15
AI status
Completed
Completed
100%
Causes
- Faulty ignition switch or start button
- Open, shorted or corroded wiring/connectors between ignition switch and BCM/ECM
- Blown ignition-related fuse or relay
- Poor battery voltage or weak battery
- Faulty BCM/ECM or other control module that senses/relays the start signal
- Intermittent CAN bus or network communication fault affecting the start command
Symptoms
- Engine does not crank or cranks intermittently when key is turned to START
- No response from starter motor while key in START
- Malfunction Indicator Lamp (MIL) or warning messages on dash
- Accessory/electrical systems behave unpredictably in START position
- Stored communication or input-related DTCs in BCM/ECM
What to check
- Use a scan tool to read freeze frame data and confirm U3010 is present and if other related codes exist
- Verify battery voltage is within specification (typically ~12–14V) before testing
- Inspect ignition switch/start button and associated connectors for damage or corrosion
- Check fuses and relays related to ignition and starter circuits
- Visually inspect wiring harness from ignition switch to BCM/ECM for chafing, breaks, or pin damage
- Check CAN bus and ground connections for continuity and secure fit
Signal parameters
- Ignition START input should show battery voltage (approx. 11–14 V) at the START terminal when the key/button is held in START
- Voltage at START should be near 0 V with key OFF or after release from START
- Signal should be continuous and stable during cranking (no rapid dropouts or excessive noise)
- If the control module uses a low-voltage logic input, expect a defined HIGH/LOW threshold per service manual (measure with scope or meter)
- CAN network messages (if used) should include a valid start request message with no errors
Diagnostic algorithm
- Connect a capable scanner and confirm U3010 and any related codes (U-codes, P-codes). Record freeze frame and live data.
- Check and record battery voltage. Recharge or replace battery if below specification before continuing.
- Visually inspect fuses/relays for ignition/starter circuits and replace any blown items.
- Inspect ignition switch or start-button assembly and wiring for damage. Wiggle harness while observing live data to detect intermittent open/short.
- With proper safety precautions, backprobe the ignition START terminal at the switch and measure voltage while operating key/button through OFF/ACC/ON/START positions. Compare to signal parameters.
- Check continuity between ignition switch and BCM/ECM connectors and verify connector pins are clean and secure.
- If available, use an oscilloscope to view the start input waveform for noise or dropouts. Also monitor CAN bus traffic for missing or corrupted start messages.
- Inspect and test relevant grounds and supply circuits to BCM/ECM. Repair any poor grounds or damaged wiring.
- If wiring and inputs test good, perform module-level diagnostics: reflash/update module software per TSBs, and if necessary swap or replace the BCM/ECM following manufacturer procedures.
- Clear codes and retest vehicle operation to verify repair. Document findings.
Likely causes
- Damaged/dirty ignition switch contacts or worn start button
- Loose or corroded connector at BCM/IGN/ECM harness
- Blown fuse or failing starter relay
- Low battery voltage preventing proper signal level
- Faulty BCM or wiring to BCM causing no recognition of START input
Fault status
Status
Ignition Input Start — start signal missing, intermittent, or invalid. May prevent starter engagement or proper start sequencing.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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