P0603 on 2008-2015 GMC Sierra 1500: Keep Alive Memory (KAM) Error Fixes

What's Unique About the 2008-2015 Gmc SIERRA 1500 🎬 Watch: A quick overview of P0603 causes and common fixes.

For the GMT900 (2008-2013) and early K2XX (2014-2015) Sierra, this code is frequently a benign side effect of other actions. It commonly appears after disconnecting the battery for service, using an aftermarket engine programmer (like DiabloSport or Bully Dog), or even from a weak battery causing a voltage drop during startup. While the TSBs confirm it can be a sign of module issues, for this truck, it's most often a simple power interruption rather than a true component failure. Poor grounds, a known issue on these trucks, are a primary suspect.

Diagnostic Flowchart

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

Generation note: This range covers two Sierra 1500 generations: the end of the 2nd Gen (GMT900, 2008-2013) and the beginning of the 3rd Gen (K2XX, 2014-2015). The causes for P0603 are consistent across both generations, primarily relating to the battery and electrical system integrity, including critical ground strap locations. The transition to the K2XX platform in 2014 introduced new engine options and more complex electrical systems, but the fundamental triggers for a KAM error remain the same.

Symptoms You May Notice

• Check Engine Light is on
• Rough or unstable idle
• Hesitation during acceleration
• Transmission may shift erratically or harshly
• Difficulty starting the engine, or extended cranking
• ABS or Traction Control light may also illuminate
• Remote start may be disabled or malfunction
• Noticeable decrease in fuel economy

Most Likely Causes

1. Weak or Failing Battery 🔴 High Probability Modern trucks have significant electrical demands. A battery that can't maintain stable voltage (staying above ~10.5V) during engine cranking can cause the PCM's volatile memory to reset, triggering P0603.
   How to confirm: Use a multimeter to check the battery voltage with the engine off (should be ~12.6V). Perform a load test to check its health. Many auto parts stores offer free battery testing. Watch for slow cranking.
   Typical fix: Replace the vehicle's battery. Common sizes for this truck are BCI Group 48 (H6) or Group 94R (H7).
   Est. part cost: $150-$350
2. Loose or Corroded Battery Terminals/Grounds 🔴 High Probability Engine vibrations can loosen ground straps, and corrosion is common. Key grounds on these trucks include the negative cable to the chassis, the strap from the firewall to the back of the cylinder head (often the passenger side, G103), and the main engine block ground. A poor ground here creates intermittent power loss to the PCM.
   How to confirm: Visually inspect battery terminals for corrosion. Physically check that all main power and ground connections are tight. Specifically locate and inspect the engine-to-firewall and battery-to-chassis grounds for corrosion or fraying.
   Typical fix: Disconnect, clean all contact points with a wire brush until shiny, apply dielectric grease to prevent future corrosion, and securely retighten all connections.
   Est. part cost: $5-$20
3. Recent Battery Disconnection or Jump Start 🟡 Medium Probability The Keep Alive Memory is volatile and is designed to be erased when all power is cut. This is a normal and expected occurrence if the battery was disconnected for service or died completely.
   How to confirm: Confirm with the vehicle owner if the battery has been recently replaced, disconnected, or jump-started. If so, this is the likely cause.
   Typical fix: Clear the code with a scanner. The code should not return if the electrical system is healthy. The PCM will relearn adaptive values as you drive (see KAM Relearn Procedure).
   Est. part cost: $0
4. Aftermarket Engine Tuner/Programmer 🟡 Medium Probability The process of flashing the PCM with a new tune from devices like DiabloSport or Bully Dog often involves power cycles or procedures that intentionally clear the KAM, logging a P0603 code as a side effect.
   How to confirm: Check if an aftermarket performance tuner is installed or has been recently used. Forum discussions often confirm this is a normal part of the tuning process.
   Typical fix: This is often considered a normal side effect of tuning. Clear the code. If it returns without re-flashing, investigate other electrical causes. If it only appears after a flash, it can usually be ignored.
   Est. part cost: $0
5. Failing Alternator ⚪ Low Probability If the alternator is failing, it may not provide consistent voltage (typically 13.5V-14.5V) to charge the battery and run the vehicle's electronics, causing voltage drops that reset the PCM's memory.
   How to confirm: With the engine running, check the voltage at the battery terminals. It should be between 13.5V and 14.5V. If it's too low, too high, or fluctuating wildly, the alternator is likely faulty.
   Typical fix: Replace the alternator.
   Est. part cost: $200-$450

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): This should be the last consideration after all power and ground issues have been ruled out. The TSBs #05-06-04-060A and #PIP4653E indicate internal module faults are possible, but it is far less common than a simple power supply problem.
• Blown Fuse or Damaged Wiring: A blown fuse in the PCM's constant power circuit (sometimes labeled 'BATT' or 'MEM') or a damaged wire in that circuit can cut power to the Keep Alive Memory. This is uncommon but worth checking with a multimeter if battery and alternator issues are ruled out.

Diagnosis Steps

1. Check if the battery has been recently disconnected or if an aftermarket tuner was used. If yes, clear the code and perform the KAM relearn procedure.
2. Visually inspect the battery terminals, positive and negative, for any signs of white or greenish corrosion. Clean and tighten as necessary.
3. Inspect the main ground connections. Key locations on GMT900/K2XX trucks are: 1) Negative battery cable to the chassis/fender. 2) Braided strap from the firewall to the rear of the passenger-side cylinder head (G103). 3) Main ground on the rear driver's side of the engine block. Ensure they are clean, free of corrosion, and tight.
4. With the engine off, test battery voltage using a multimeter. A healthy battery should read approximately 12.6 volts.
5. Start the engine and test the alternator output at the battery terminals. The voltage should be stable, between 13.5 and 14.5 volts.
6. If the battery is more than 4 years old or if voltage is low, have it professionally load-tested at an auto parts store.
7. Check fuses related to the PCM or ECM. Look for a fuse designated for memory or constant power.
8. If all power and ground systems are confirmed to be good and the code persists after clearing, the issue may be with the PCM itself, though this is rare.

Parts You'll Likely Need

• Vehicle Battery (OEM #ACDelco Gold 48AGM (Group 48/H6) or 94RAGM (Group 94R/H7) are common AGM replacements.) — A weak or failing battery is the most frequent cause of the P0603 code due to voltage drops during cranking.
  Trusted brands: ACDelco, DieHard, Interstate, Optima
  OEM price range: $200-$350
  Aftermarket price range: $150-$300
• Battery Terminal Cleaners/Protectors — To fix poor electrical connections at the battery, which is a very common cause of intermittent power loss to the PCM.
  Trusted brands: NOCO, CRC
  OEM price range: $10-$20
  Aftermarket price range: $5-$15
• Battery Hold Down (OEM #Dorman 00587 (Example Aftermarket Kit)) — If the original hold-down is missing or broken, the battery can vibrate excessively, leading to intermittent connections and premature failure.
  Trusted brands: Dorman, ACDelco
  OEM price range: $15-$30
  Aftermarket price range: $10-$25

Related Codes That Often Appear With This One

• P0601 — Indicates an internal memory checksum error in the control module. Often appears with other P06xx codes when there is a module fault. [⭐ MANUFACTURER TSB — highest authority] Bulletin #05-06-04-060A
• P0604 — Indicates a Random Access Memory (RAM) error within the control module. [⭐ MANUFACTURER TSB — highest authority] Bulletin #PIP4653E
• P1621 — A GM-specific code related to control module long-term memory performance, often seen with other module memory codes. [⭐ MANUFACTURER TSB — highest authority] Bulletin #PIP4653E

Technical Service Bulletins (TSBs) & Recalls

• Bulletin #05-06-04-060A: Communicates that P0603 is one of several DTCs that can be shared in multiple control modules, cautioning against immediate module replacement.
• Bulletin #PIP4653E: Notes that P0603 may be found in the Transmission Control Module and provides diagnostic information, suggesting a system-wide power or communication issue.

Platform-Specific Known Issues

• GM has issued Technical Service Bulletin #05-06-04-060A, which is an informational bulletin noting that P0603 can appear along with other P06xx codes and may be shared across multiple control modules, suggesting a potential systemic electrical issue rather than a single component failure.

Mechanic-Grade Diagnostic Values

• Battery Voltage (Engine Off) — expected: ~12.6 Volts. Failure: Below 12.4V suggests a discharged or failing battery. Below 12.0V is significantly discharged.
• Alternator Output Voltage (Engine at Idle) — expected: 13.5 - 14.5 Volts. Failure: Voltage below 13.2V or above 15.0V, or wildly fluctuating voltage, indicates a faulty alternator or voltage regulator.
• PCM Power and Ground Pin Voltage Drop — expected: < 0.1 Volts (100 millivolts). Failure: Voltage drop greater than 0.1V on a ground circuit or between the battery positive post and the PCM's constant power pin indicates excessive resistance in the wiring or connections.

Scan Tool Commands That Help

• GDS2 / Tech2: Clear DTCs — After a battery replacement or any power interruption, a P0603 code is expected. Use the scan tool to clear the code. If it does not return after a drive cycle, the issue was the power loss itself and no further repair is needed.
• GDS2 / Tech2: Module Information / ID Information — To verify the correct software and calibration files are loaded onto the PCM, especially if the vehicle has been previously tuned or had a PCM replacement. Incorrect programming can sometimes trigger memory-related codes.

Wiring & Ground Locations

• G103 — On the front of the passenger side (right) cylinder head for most V8s. On GMT900s, it can also be a braided strap from the firewall to the rear of the passenger-side cylinder head.. This is a primary ground point for the Engine Control Module (ECM) and Body Control Module (BCM). Corrosion or looseness here is a very common cause of intermittent power loss and codes like P0603.
• G104 — On the rear of the driver side (left) cylinder head. A ground strap often runs from here to the firewall (G108).. Provides a critical ground path for the engine harness and various components. A loose connection here can cause a range of electrical gremlins.
• G108 — On the firewall, driver's side, often serving as the termination point for the ground strap from G104.. This is a key chassis grounding point. If the connection to the firewall is corroded, it can disrupt the ground for the entire engine harness.
• G100 / G101 — Located on the lower left (G100) and lower right (G101) of the radiator core support.. These ground forward-mounted components like lights and horns, but also serve as part of the overall chassis ground network that the PCM relies on.
• Underhood Fuse Block (X50A) — Located on the driver's side of the engine compartment.. This fuse block is the power distribution center. The main battery positive cable connects here. Internal corrosion or a poor connection at the main stud can cause voltage drops to all systems, including the PCM's keep-alive power feed.
• PCM Connectors (X1, X2) — The PCM is located in the left front of the engine compartment, near the fan shroud. It has multiple large connectors, often color-coded or labeled X1, X2, etc.. The constant battery power (Keep Alive Power) pin must be tested directly at the PCM connector to confirm power is reaching the module. A wiring diagram is needed to identify the specific pin for your year/engine (e.g., Pin 18, Pink wire on some models).

Real Owner Repair Stories

• GM-Trucks.com forum user (2011 GMC Sierra 1500) — Check engine light with P0603, remote start not working.
  ❌ Tried (didn't work) Clearing the code (it would return immediately), Checking battery and alternator (both tested good), Inspecting main engine grounds (they appeared clean and tight)
  ✅ What actually fixed it The owner discovered a faulty aftermarket remote start system had been poorly installed. A power wire for the remote start module was tapped into a critical PCM power source, causing a voltage drain. Removing the aftermarket remote start system and repairing the spliced wire permanently resolved the P0603 code.

Model Year Variations Within This Range

• 2014-2015 (K2XX Platform): The K2XX generation introduced direct-injected EcoTec3 engines (LV3, L83) and a more integrated electrical architecture. While the root causes of P0603 remain the same (power interruption), the specific PCM connectors and some ground locations may differ slightly from the earlier GMT900 trucks. The 8-speed 8L90 transmission also became available, which relies heavily on adaptive data stored in KAM.
• 2008-2013 (GMT900 Platform): These trucks primarily used the Gen IV V8 engines. The 4-speed (4L60-E) and 6-speed (6L80-E) transmissions were common. The electrical architecture is slightly less complex than the K2XX, but they are well-known for ground issues, particularly the G103 and G104/G108 ground straps.