Intermittent Charging System Anomaly on a 2011 Kia Sedona EX

Modified on Mon, Nov 10 at 3:54 PM

This technical case study details the advanced diagnosis of a persistent, intermittent charging system failure and stalling anomaly on a 2011 Kia Sedona EX (3.5L V6). After multiple failed alternator and battery replacements, the focus shifts to finding elusive high-resistance faults in terminations, grounds, and control relays. The guide outlines a precise diagnostic strategy utilizing Thermal Imaging (TI) and specialized electrical testing to pinpoint the true cause of the chronic electrical failure.

Part I: Vehicle Specifications and Failure History

This section documents the vehicle details and the chronic, recurring nature of the electrical failure.

Vehicle Technical Specifications

Feature	Specification	Notes
Model/Trim	2011 Kia Sedona EX	Full-size minivan platform.
Engine	3.5L DOHC 24-valve V6 (Lambda II G6DC family)	Shared platform with various Hyundai/Kia models.
Mileage	Approx. 138,000 miles	Trouble-free for the first 138k miles.
Alternator Rating	150 Amps (Industry Standard) or 130 Amps (Car & Driver Spec)	The original equipment is internally regulated and typically communicates with the ECM.
Charging Control	ECM-controlled (likely PWM or LIN/BSS protocol)	The Engine Control Module manages alternator output based on system voltage and battery sensor input.
High-Current Protection	Relies on high-amperage bolt-in Multi-Fuses and dedicated relays.	Located in the Engine Compartment Fuse/Relay Box.

Observed Failure History (Last 3 Months)

The vehicle has exhibited a classic intermittent charging failure followed by a system shutdown.

Event	Action Taken	Failure Behavior
1st Issue	Replaced battery and alternator.	Driving normally, dash indicators (Battery, TPMS, Airbag) flashed, with the Battery Light coming on first and remaining steady. Vehicle eventually stalled.
2nd Issue	Checked battery/alternator (tested OK), deep-cleaned all terminals, removed a high-draw aftermarket sound system (rated up to 200A max draw).	Same behavior: Battery light, multiple indicator flashes, drove ~5 miles until stalling.
3rd Issue	Checked battery (OK), Replaced Alternator (again).	After driving normally for a period, the exact same stalling behavior recurred.
Current Status	4 tow bills, 3 alternators, 1 battery, stereo delete, and lots of time and trouble later, here we still are	The van sits due to the intermittent, recurring anomaly—a sudden, complete charging system failure and stall.

Conclusion from History: The repetitive nature of the failure, despite multiple component replacements, strongly suggests a persistent, high-resistance fault in the wiring, a critical relay/contactor, or a systemic incompatibility with non-OEM parts.

Part II: Advanced Diagnostic Plan (The Search for the Contactor Anomaly)

The diagnostic plan is structured to move past component replacement and target the intermittent electrical failure points—the high-resistance terminations, grounds, and control components.

Phase A: High-Priority Thermal Imaging (TI) Inspection Protocol

Using a thermal camera is the ideal method to find a high-resistance fault, as the anomaly will appear as a "hot spot" under load.

Step	Rationale	Critical Targets for Inspection
1. Cold Soak & Load	Maximizes the temperature differential to make high-resistance visible.	Start from cold. Activate Max Load (High Beams, HVAC blower on High, Rear Defrost).
2. Scan Positive Path	The highest current flows between the alternator and the battery.	Alternator B+ Post and cable lug; Engine Bay Distribution Block terminals; Battery Terminal Clamps (looking at the crimp behind the post).
3. Scan Ground Path	High resistance on the negative side is the most common cause of systemic electrical failure.	Engine Block Ground Strap (Battery to Engine); Chassis Ground Points (Battery/Engine to Frame/Fender).
4. Scan High-Current Relays	Relay contacts or their sockets act as high-current "contactors."	MAIN RELAY (ECM Power) in the Engine Bay Fuse Box. Scan the relay body and the plastic fuse box socket for heat.

Phase B: Electrical and Component Verification

These tests verify the health of the high-current components that are typically not visible.

Component Group	Check Method	Acceptance Criteria / Action
Main Alternator Fuse/Link	Voltage Drop Test (Engine Running, Full Load) across the bolt-in Multi-Fuse (e.g., 150A) in the engine box.	Must be <0.05 Volts DC @ 50 mV. A higher reading means internal resistance failure.
Main Relays (ECM Power)	Relay Swap Test with the MAIN RELAY and other critical Ignition Relays (IG1/IG2).	Swapping with an identical, known-good relay eliminates intermittent internal contact failure.
Alternator Control Wires	Wiggle Test on the small wire harness plug at the alternator.	Monitor charging voltage while gently wiggling the harness to check for intermittent signal loss to the ECM.
Battery Current Sensor	Visual Inspection of connections on the sensor located on the negative battery cable (if equipped).	Ensure clean, secure connection. A faulty signal here disrupts the ECM's ability to command charging.

Phase C: Part Quality Conclusion

Based on common reports for this platform, part quality must be the final consideration if a physical fault (termination or relay) is not found.

Component	Recommendation	Reasoning
Alternator	Final replacement should be a Genuine Kia OEM Alternator.	Numerous documented cases show that low-quality or incompatible aftermarket units are a recurrent source of failure, even if they test "good" initially.

This article will be updated as further diagnostic data is collected.