P1105
HyundaiDual Alternator Upper Fault
High SeverityThe P1105 code indicates an issue with the upper alternator in a dual alternator system on a Hyundai vehicle. This fault means that the vehicle's electrical system may not be receiving adequate charging from both alternators, potentially leading to a drained battery and loss of power to crucial components.
⚠️ Before You Begin (Safety First)
Always disconnect the battery before performing any inspection or repair on the charging system to avoid electrical shock or short circuits. Be cautious of hot engine components and moving belts.
Common Symptoms
- Battery warning light illuminated on the dashboard
- Dim headlights or interior lights
- Difficulty starting the engine
- Warning messages related to charging system or battery
- Malfunctioning electrical accessories
Common Causes
- Faulty upper alternator
- Damaged or loose alternator drive belt
- Corroded or loose wiring connections at the upper alternator
- Failed voltage regulator (often integrated into the alternator)
- Issue with the Engine Control Module (ECM) or Powertrain Control Module (PCM)
Frequently reported on: Hyundai H-1 (Starex) 2007-2018, Hyundai Porter H100 2004-2023, Hyundai HD Series Trucks
Diagnostic Steps
- Inspect the upper alternator and its drive belt for signs of wear, looseness, or damage.
- Check all wiring and connectors to the upper alternator for corrosion, fraying, or loose connections.
- Use a multimeter to test the battery voltage with the engine off and then with the engine running to check charging output.
- Verify all relevant fuses in the engine bay fuse box are intact and not blown.
- If accessible and comfortable, remove the upper alternator and have it bench tested at an auto parts store.
👨🔧 When to Call a Professional
If the battery warning light remains on after clearing the code and checking the basic components, or if you notice significant electrical issues, it is time to consult a professional mechanic for advanced diagnostics.
Commonly Asked Questions
What does P1105 specifically mean for a Hyundai?
For Hyundai, P1105 indicates a 'Dual Alternator Upper Fault', meaning there's an issue with the charging output or communication from the vehicle's upper alternator.
Can I drive my Hyundai with a P1105 code?
It is not recommended to drive with a P1105 code for long, as it signifies a problem with the charging system. Your battery may eventually drain, leaving you stranded.
How do I identify which is the 'upper' alternator?
In a dual alternator system, the upper alternator is typically mounted higher on the engine block. Consult your vehicle's service manual for exact location.
What tools do I need to diagnose P1105?
You will need a multimeter for electrical testing, basic hand tools for inspection, and potentially a specialized alternator belt tensioner tool if replacement is needed.
Is it common for Hyundai vehicles to have dual alternators?
Dual alternators are not common in most standard Hyundai passenger cars but can be found in larger SUVs, commercial vehicles, or models designed for heavy electrical loads.