P0562 on 2024 GMC Sierra 2500: System Voltage Low Causes and Fixes

What's Unique About the 2024-2024 Gmc SIERRA 2500

For the 2024 GMC Sierra 2500, P0562 is not always a straightforward charging system problem. GM has issued a Technical Service Bulletin (TSB #24-NA-050) indicating that P0562 can be set alongside code P0606 (Control Module Processor Fault). This specific combination points to a software anomaly in the Electronic Brake Control Module (EBCM), which misinterprets a temporary voltage drop (like during engine cranking) and sets the codes. The fix is an EBCM software update, not a module replacement. Additionally, other GM bulletins for recent Sierra models (TSB #PIT5689 series) highlight issues with engine-to-body ground straps at the passenger-side firewall (G132, G134) which can also cause low voltage and a variety of other electrical DTCs.

Diagnostic Flowchart

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

Symptoms You May Notice

• Check Engine Light is on
• "Service Stabilitrak" message may appear
• Battery or charging system warning light may be on
• Dimming or flickering headlights and interior lights
• Difficulty starting the engine, or a no-start/no-crank condition
• Engine may stall, especially after an auto-stop event
• Erratic behavior from electrical components like the radio, instrument cluster, or HVAC system
• Instrument cluster may intermittently fail to turn on
• Intermittent loss of audio from speakers and no turn signal sounds

Most Likely Causes

1. EBCM Software Anomaly per TSB #24-NA-050 🔴 High Probability This is a documented issue by GM for 2024 Sierra/Silverado HD trucks. The EBCM software is overly sensitive to voltage fluctuations during events like cranking or jump-starts, causing it to erroneously set P0606 and P0562.
   How to confirm: Scan for additional trouble codes. If P0606 is present along with P0562, this is the most likely cause. The TSB explicitly states not to replace the EBCM for this condition.
   Typical fix: A GM dealer will reprogram the Electronic Brake Control Module (EBCM) with an updated calibration. This is primarily a software fix. The battery should also be tested as a low state of charge can trigger the event.
   Est. part cost: $0
2. Loose or broken engine/body ground straps 🟡 Medium Probability → Shop Engine Ground Strap GM TSB #PIT5689 and its successors cover 2020-2025+ models, indicating that poor ground connections at the passenger-side firewall (specifically G132 and G134) are a known failure point causing widespread electrical issues, including P0562.
   How to confirm: Visually inspect the main ground straps connecting the engine to the body on the passenger-side firewall. Check for looseness, corrosion, or breakage. A voltage drop test across the ground circuit can confirm high resistance; the drop should not exceed 0.1V (100mV). 🎬 See this guide on fixing common GM ground connection issues.
   Typical fix: Clean and tighten the ground connections. If the strap is corroded or broken, it must be replaced. Ensure the strap is oriented correctly to allow for engine movement without stress.
   Est. part cost: $20-$80
3. Weak or failing battery 🟡 Medium Probability → Shop Vehicle Battery
   How to confirm: Measure the battery voltage with the engine off; a healthy battery should be around 12.6 volts. If it's below 12.4V, it's discharged. The most reliable method is to have the battery professionally load-tested, as it can show good voltage but still fail under load.
   Typical fix: Replace the battery.
   Est. part cost: $200-$400
4. Failing alternator ⚪ Low Probability → Shop Alternator
   How to confirm: With the engine running, measure the voltage at the battery terminals. A healthy alternator should maintain a voltage between approximately 13.5 and 14.7 volts. If the voltage is low, doesn't increase with RPM, or is excessively high, the alternator/voltage regulator is likely faulty. 🎬 Watch: An easy way to diagnose a failing alternator.
   Typical fix: Replace the alternator.
   Est. part cost: $400-$800

Rare But Worth Checking

• Loose or corroded battery terminals or power cables: → Shop Vehicle Battery A simple but often overlooked cause. Inspect both positive and negative battery cable connections at the battery, chassis, and starter for any signs of corrosion or looseness.
• High-resistance parasitic draw: A module or component may fail to enter 'sleep mode' when the vehicle is off, slowly draining the battery. A normal draw is under 50mA after all modules have gone to sleep (which can take over 20 minutes). A draw exceeding this can discharge the battery overnight, leading to a P0562 on the next startup.

Diagnosis Steps

1. Use an OBD-II scanner to check for any other codes stored alongside P0562. The presence of P0606 is a critical clue pointing to a specific TSB.
2. If P0606 is present, refer to GM TSB #24-NA-050. The vehicle requires service at a GM dealership for an EBCM software update. Do not replace the module.
3. If P0562 is stored alone or with other U-codes, the next step is to inspect physical connections.
4. Visually inspect the battery terminals for looseness and corrosion. Clean and tighten as needed.
5. Inspect the main engine-to-body ground straps (G132, G134) on the passenger-side firewall for tightness, corrosion, and integrity, as noted in TSB #PIT5689H and its successors.
6. With the engine off, use a multimeter to check the battery's state of charge. A reading of 12.6V is healthy; below 12.4V indicates it is discharged. Have the battery professionally load-tested to confirm its health.
7. Start the engine and measure the voltage at the battery terminals. It should be between 13.5 and 14.7 volts. If it's low, and all connections/grounds are good, the alternator is the likely culprit.

Parts You'll Likely Need

• EBCM Reprogramming — If P0562 is accompanied by P0606, this is the official GM fix per TSB #24-NA-050. It is a labor/software procedure, not a physical part replacement.
  Trusted brands: GM Dealer Service
  OEM price range: $150-$300
  Aftermarket price range: N/A
• Battery — A weak or failing battery is a common cause for any low voltage code and can be the trigger for the EBCM software issue. Modern trucks have high electrical demands that can wear out batteries in 3-5 years.
  Trusted brands: ACDelco, Odyssey, NorthStar
  OEM price range: $250-$400
  Aftermarket price range: $200-$350
• Ground Strap — A known issue on these trucks (per TSB #PIT5689 series) is a poor ground connection at the passenger-side firewall, which can cause P0562 and other electrical faults.
  Trusted brands: ACDelco, Standard Motor Products
  OEM price range: $40-$80
  Aftermarket price range: $20-$50
• Alternator — The alternator is responsible for charging the battery and powering the truck when running. If it fails after other causes are ruled out, system voltage will drop.
  Trusted brands: ACDelco, Denso
  OEM price range: $500-$800
  Aftermarket price range: $400-$650

Related Codes That Often Appear With This One

• P0606 — As per TSB #24-NA-050, this code is set by the EBCM due to a software anomaly when it detects low or high voltage (P0562/P0563). It is the key indicator for the EBCM reprogram fix.
• P0563 — This code for 'System Voltage High' can also be set along with P0606 according to TSB #24-NA-050, indicating erratic voltage regulation related to the same EBCM software anomaly.
• U-codes (e.g., U0102, U0106, U111A) — Poor ground connections, as described in TSB #PIT5689L, interrupt communication between modules, causing a flood of communication loss (U-prefix) codes along with voltage and performance codes.

Technical Service Bulletins (TSBs) & Recalls

• 24-NA-050: Provides repair information for a condition where DTC P0606 is set with either P0562 or P0563 due to an EBCM software anomaly. The fix is to reprogram the EBCM.
• PIT5689H (and successors like L/M): Addresses concerns like no-start, dead battery, and various DTCs (including P0562) caused by a broken or loose engine ground cable/strap at the passenger-side firewall.

Platform-Specific Known Issues

• TSB #24-NA-050: Documents a software anomaly in the Electronic Brake Control Module (EBCM) where DTC P0606 is set with P0562 or P0563. The fix is an EBCM reprogram, not replacement.
• TSB #PIT5689H (and successors): Points to loose or broken engine-to-body ground straps at the passenger-side firewall (G132/G134) as a cause for no-start, dead battery, and numerous DTCs including P0562 on 2020-2025 models.

Mechanic-Grade Diagnostic Values

• Battery Voltage (engine off) — expected: ~12.6V. Failure: Below 12.4V indicates a discharged state.
• Alternator Charging Voltage (engine running, no load) — expected: 13.5V - 14.7V. Failure: Voltage below 13.5V or above 15.0V.
• Alternator Charging Voltage (engine running, with electrical load) — expected: Should stay above 13.0V. Failure: Voltage drops below 13.0V with accessories (lights, HVAC) on.
• Voltage Drop (Ground Cable/Strap) — expected: < 0.1V (100mV). Failure: A reading greater than 0.1V indicates high resistance in the ground circuit.
• Voltage Drop (Positive Battery Cable) — expected: < 0.2V (200mV). Failure: A reading greater than 0.2V from the battery positive post to the alternator B+ terminal indicates high resistance.
• Parasitic Draw (after 20-30 min sleep time) — expected: < 50mA. Failure: A steady reading above 50mA indicates a module or component is not shutting down and is draining the battery.

Scan Tool Commands That Help

• GM GDS2 (or equivalent professional scan tool): Clear DTCs in EBCM — According to TSB #24-NA-050, simply disconnecting the battery may not clear the P0606 code from the EBCM. A service tool must be used to erase the code after the battery has been tested/replaced and the system is verified.
• GM GDS2 (or equivalent professional scan tool): EBCM Reprogramming — This is the specific fix mandated by TSB #24-NA-050 when P0562 is found with P0606. It involves updating the module's software with a new calibration to make the voltage diagnostics more robust.

Wiring & Ground Locations

• G132 / G134 — On the passenger-side firewall. G132 is the body connection point, and G134 is where the strap from the engine connects.. This is the primary engine-to-body ground path. TSB #PIT5689M identifies a loose, broken, or corroded connection here as a root cause for P0562 and a host of other seemingly unrelated electrical fault codes due to unstable module voltage.
• Alternator B+ Terminal — The main, large-gauge wire connection post on the back of the alternator, typically covered by a black or red rubber boot.. This is the primary output of the charging system. High resistance from corrosion or a loose nut at this point will prevent the alternator from properly charging the battery and powering the vehicle, directly causing a low voltage condition.