P0562 on 2013 Ram 3500: Diagnosing and Fixing Low System Voltage

What's Unique About the 2013-2013 Ram 3500

For the 2013 Ram 3500, particularly those with the 6.7L Cummins engine, the P0562 code doesn't always point to a bad part. The high electrical draw of the diesel grid heater during cold starts can cause a significant temporary voltage drop, which a sensitive or outdated ECM calibration may flag as a fault. Ram has issued several Technical Service Bulletins (TSBs) indicating that this code can be triggered erroneously, often with other unrelated codes. In these cases, the actual fix is a software update for the Engine Control Module (ECM), which a dealer must perform. Therefore, it's crucial to rule out a software issue before replacing expensive hardware 🎬 Watch: Understanding P0562 causes and how to fix low voltage. like the alternator.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Generation note: This issue is common across the 4th Generation of Ram Heavy Duty trucks (2010-2018) equipped with the 6.7L Cummins engine, as they share the same basic electrical architecture, dual-battery setup, and are covered by the same TSBs.

Symptoms You May Notice

• Check Engine Light is on
• Battery warning light is on
• Dimming or flickering headlights and interior lights
• Slow engine cranking or failure to start
• Engine stalling, especially at idle or when shifting into gear after a jump start
• Erratic behavior from electrical components like the radio, power windows, or instrument cluster gauges
• Whining or grinding noise from the engine bay, which changes with RPM
• "Service Charging System" message on the dash display

Most Likely Causes

1. Failing Alternator 🔴 High Probability → Shop Alternator The alternator is a common failure point. The high electrical demands of the 6.7L Cummins, including the grid heater and emissions systems, put extra strain on the charging system. Owners report failures, and some alternators on these trucks feature a clutch pulley that can fail, preventing the alternator from spinning correctly even if the belt is fine.
   How to confirm: With the engine running, use a multimeter to test the voltage at the battery terminals. A healthy alternator should produce between 13.7 and 14.7 volts. If the voltage is low, fluctuating, or doesn't increase from the resting battery voltage, the alternator is likely faulty. Also test voltage at the alternator's main output stud to check for voltage drops across the wiring.
   Typical fix: Replace the alternator. These trucks typically use a 180A or 220A unit.
   Est. part cost: $323 - $713
2. Weak or Defective Batteries 🔴 High Probability Batteries have a finite lifespan of 3-5 years. The 2013 Ram 3500 diesel uses two batteries (typically Group Size 94R/H7) to handle the high demand of the starter and grid heater. This doubles the chance of a cell failure. A single bad battery can drain the good one and pull the whole system voltage down.
   How to confirm: Test each battery individually with the engine off; a healthy battery should read about 12.6 volts. For a definitive diagnosis, disconnect the batteries from each other and take them to an auto parts store for a load test, which is usually a free service. A battery can show good voltage but fail under load.
   Typical fix: Replace the faulty battery. It is best practice to replace both batteries at the same time to ensure they are balanced in age and capacity.
   Est. part cost: $220 - $435 per battery
3. Loose or Corroded Battery Terminals/Cables 🟡 Medium Probability → Shop Vehicle Battery Vibration from the diesel engine and exposure to the elements can lead to loose connections or corrosion on the battery terminals and ground straps. These trucks are known to be sensitive to poor connections, especially after driving on rough roads.
   How to confirm: Visually inspect the battery terminals, cable ends, and main ground connections to the chassis and engine block. Look for white or greenish powder (corrosion) and ensure all connections are tight. A voltage drop test across the cables can identify high resistance not visible to the eye.
   Typical fix: Clean the terminals and cable ends with a wire brush and baking soda solution. Tighten all connections securely. Replace cables if corrosion is severe.
   Est. part cost: $5 - $50
4. Outdated Engine Control Module (ECM) Software ⚪ Low Probability As cited in multiple TSBs (e.g., 18-030-14 Rev. B), the factory software may be too sensitive, causing it to set P0562 incorrectly, often alongside a cluster of other unrelated emissions codes. The update changes the fault from a one-trip to a two-trip fault, making it less likely to trigger from a momentary dip.
   How to confirm: This can only be confirmed by a Ram dealership. If the batteries and alternator test good, and the code appears with others listed in TSBs like #18-030-14, a software issue is the likely cause.
   Typical fix: The dealer will reprogram (or "flash") the ECM with updated software. This is often performed under warranty or as part of a recall.
   Est. part cost: $0 - $200 (Labor cost for flashing)

Rare But Worth Checking

• Blown Generator Fuse: On these Ram trucks, a large mega-fuse for the generator is located on the positive battery terminal itself, not in the main fuse box. If this fuse blows, the alternator is completely disconnected from the batteries and cannot charge them.
• Damaged Wiring Harness: Owners have reported issues with wires chafing in the engine bay, leading to shorts and various electrical problems, including charging system faults. Common chafe points are where the harness may rub against the engine block or chassis components.
• Faulty Powertrain Control Module (PCM): While rare, the PCM itself can fail, causing incorrect voltage readings or failing to properly command the alternator to charge. This should be considered only after all other possibilities, including wiring and grounds, have been exhaustively checked.

Diagnosis Steps

1. Read the codes: Use an OBD-II scanner to confirm P0562 and document any other stored codes. Note if they match the codes listed in TSBs.
2. Visual Inspection: Carefully inspect both batteries' terminals, the main power distribution center, cables, and ground straps for corrosion, damage, or loose connections.
3. Test Battery Voltage (Engine Off): Disconnect the negative terminal on one battery to isolate them. Test each battery's voltage individually with a multimeter. It should be ~12.6V. A reading below 12.4V indicates a discharged or weak battery.
4. Load Test the Batteries: Take both batteries to an auto parts store for a free load test to confirm their health. A battery can show good voltage but fail under load.
5. Test Charging System Voltage (Engine Running): Reconnect everything. Start the engine and measure the voltage at the battery terminals. It should be between 13.7V and 14.7V. If it's low, proceed to the next step.
6. Test Alternator Output: Measure voltage directly at the alternator's B+ output post. If voltage is high here but low at the batteries, you have a wiring/fuse issue. If voltage is low at the alternator, the alternator itself is likely faulty.
7. Check Fuses: Inspect the main generator fuse located on the positive battery terminal assembly.
8. Check for TSBs: If the batteries and alternator test good, consult a dealer about TSBs #18-030-14 REV. B and #18-062-14. A software reflash is the likely fix, especially if other TSB-related codes are present.

Parts You'll Likely Need

• Alternator (OEM #56029707AC (replaces 56029707AA, 56029707AB)) — This is the most common hardware failure for P0562, as it is responsible for charging the batteries and powering the truck's electrical systems while running.
  Trusted brands: Mopar, Bosch, Denso
  OEM price range: $722+
  Aftermarket price range: $250-$450
• Battery (Group Size 94R/H7) (OEM #BB94R750AA (or superseding part)) — A battery that can no longer hold a proper charge is a primary cause of low system voltage. Diesel models use two, and it's recommended to replace them in pairs.
  Trusted brands: Mopar, DieHard, Odyssey, X2Power
  OEM price range: $260+
  Aftermarket price range: $220-$435
• Battery Terminals/Cables — Corroded or damaged cables create high resistance, leading to voltage drops that can trigger this code. The positive terminal assembly also houses the main alternator fuse.
  Trusted brands: Mopar, Standard Motor Products
  OEM price range: $50-$150
  Aftermarket price range: $20-$80

Related Codes That Often Appear With This One

• P0544 — Exhaust Gas Temperature Sensor Circuit. This code is listed alongside P0562 in multiple TSBs, suggesting a potential link through an ECM software issue that a reflash can resolve.
• P20EE — SCR NOx Catalyst Efficiency Below Threshold. Also mentioned in TSBs with P0562, pointing to a common software-related cause on diesel models that a dealer update is designed to fix.
• P04DB — Crankcase Ventilation System Disconnected. Its appearance with P0562 in TSBs suggests a dealer software update may resolve both by adjusting fault sensitivity.
• P0604 — Internal Control Module RAM Error. This code is also listed in TSB #18-030-14 REV. B, indicating the cluster of codes is likely due to a software glitch rather than multiple hardware failures.

Technical Service Bulletins (TSBs) & Recalls

• 1803014REVB: Mentions P0562 - Battery Voltage Low among a list of codes addressed by a PCM software update.
• 18-030-14 REV. B: Lists P0562 as part of a group of DTCs that can be resolved with a software flash.
• 18-062-14: Includes P0562 in a list of codes related to diagnostic and system improvements via a software update.
• 18-030-14: An earlier version of the TSB also listing P0562 as a code addressed by a software update.
• 18-018-13 REV. A: Lists P0562 with other codes that may be fixed by a PCM reflash.

Platform-Specific Known Issues

• Multiple Technical Service Bulletins (e.g., #18-030-14 REV. B, #18-062-14) indicate that an Engine Control Module (ECM) software update is a potential fix for P0562, especially when it appears with other specific codes.
• Owner complaints on forums like CumminsForum.com and RamForum.com frequently point to one of the two batteries failing and causing the code. A common story involves replacing the alternator only to find the problem persists until both batteries are replaced.
• The alternator on the 6.7L Cummins is located low on the driver's side of the engine and can be difficult to access without removing the airbox and intake tubing. Several YouTube videos demonstrate the process.