P0603 on 2007-2010 Chevrolet Silverado 2500: Keep Alive Memory (KAM) Error Causes and Fixes

What's Unique About the 2007-2010 Chevrolet SILVERADO 2500

On these heavy-duty Chevrolet trucks, P0603 is frequently a 'ghost' code triggered by the high electrical demands of the vehicle, especially during startup. For Duramax diesel models with dual batteries, a voltage imbalance or weakness in just one battery can trigger the code. A weak battery, poor ground connections, or the use of aftermarket performance tuners are very common triggers. The provided NHTSA TSBs confirm that GM is aware of these codes appearing, sometimes specifically in the Transmission Control Module (TCM), which can directly impact shift quality.

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
• Rough or inconsistent idle
• Harsh or erratic transmission shifting
• Reduced fuel economy
• Engine may be hard to start or won't start
• Illuminated ABS or traction control light
• Intermittent engine stumble or stalling

Most Likely Causes

1. Weak or Failing Battery 🔴 High Probability These large trucks have high electrical demands. Diesel models with two batteries are especially sensitive; both batteries must be in good health and properly balanced. A voltage drop during glow plug operation or cranking is the number one cause of KAM reset.
   How to confirm: Perform a load test on the battery (or batteries). A simple voltage check is not enough, as a battery can show 12.6V but fail under load. Most auto parts stores will do this for free. For dual-battery systems, you must isolate each battery to test it individually.
   Typical fix: Replace the vehicle's battery. On diesel models, it is critical to replace both batteries at the same time with two new batteries of the same type and age to prevent charging imbalances. 🎬 See this walkthrough for replacing dual batteries on a Duramax.
   Est. part cost: $150-$400
2. Loose or Corroded Battery Terminals/Grounds 🟡 Medium Probability Battery terminals can accumulate corrosion, and the main chassis and engine block grounds can become loose or corroded over time, causing intermittent power loss. A key ground to check is the strap from the passenger side cylinder head to the firewall/body, which is a known failure point.
   How to confirm: Visually inspect the battery terminals for white or greenish corrosion. Physically check that all battery cables and major ground straps are tight and clean. Key locations include battery-to-frame, frame-to-engine-block, and body-to-cylinder-head. 🎬 Watch: How to upgrade and fix common GM ground issues.
   Typical fix: Disconnect the battery, thoroughly clean the terminals, cable ends, and chassis/engine ground points with a wire brush, and re-secure them. Apply dielectric grease to prevent future corrosion.
   Est. part cost: $5-$20
3. Recent Battery Disconnect or Replacement 🟡 Medium Probability Any time the battery is disconnected for service, the KAM is erased. This is a normal occurrence and will set the code.
   How to confirm: If the battery was just replaced or disconnected for other service, this is the expected cause.
   Typical fix: Clear the code with a scanner. The code should not return after several drive cycles. If it does, another issue is present.
   Est. part cost: $0
4. Aftermarket Performance Tuner/Programmer 🟡 Medium Probability Handheld tuners (like DiabloSport, Edge, EFI Live) that re-flash the ECM or TCM are popular on these trucks and can sometimes cause software conflicts or leave behind memory errors, especially if the flash process is interrupted or battery voltage is unstable during the flash.
   How to confirm: If a tuner is or was installed, this is a strong possibility. The code may appear only when a performance tune is loaded.
   Typical fix: Return the vehicle's programming to the stock factory tune using the tuner. Clear the codes and see if P0603 returns. If it doesn't, the tuner's software was the cause.
   Est. part cost: $0

Rare But Worth Checking

• Failing Alternator: An alternator that isn't charging properly (producing less than ~13.7V) or has a failing voltage regulator (causing voltage spikes or drops) can lead to a low battery state, which then triggers the P0603 code.
• Parasitic Battery Drain: A component that doesn't shut off correctly (like an aftermarket stereo, alarm, or a faulty module) can drain the battery overnight, causing a low voltage condition on startup that triggers the code.
• Faulty PCM/TCM: This is the least likely cause. A control module should only be replaced after all other possibilities—battery, cables, grounds, charging system, and wiring—have been exhaustively ruled out.

Diagnosis Steps

1. Check if the battery has been recently disconnected or replaced. If so, clear the code and drive the vehicle to see if it returns. If not, proceed.
2. Visually inspect the battery terminals, posts, and cable ends for corrosion or damage. Ensure they are clean and tight. On Duramax models, inspect the crossover cable between the two batteries.
3. Perform a battery load test. This is the most definitive test for battery health. For diesel trucks, each battery must be disconnected and tested individually.
4. Using a multimeter, check the charging system voltage with the engine running at the battery posts. It should be stable and between ~13.7-14.7V.
5. Inspect the main ground connections. Key locations on this platform include: the negative battery cable to the passenger side cylinder head, a body strap to the driver's side cylinder head, and the battery-to-frame ground under the driver's side.
6. If an aftermarket tuner is installed, return the vehicle to its stock tune, clear the code, and re-test to see if the code returns.
7. If the code persists, check for parasitic draw using a multimeter in ammeter mode on the negative battery cable to find any circuits drawing power when the vehicle is off.
🎬 Watch: How to test for a parasitic battery drain.
8. As a final step, inspect the wiring harness and connectors at the PCM and TCM for any signs of damage, corrosion, or moisture intrusion.

Parts You'll Likely Need

• Vehicle Battery (OEM #ACDelco Gold 48AGM (Group 48/H6 AGM) is a common fitment, but confirm based on engine type (gas vs. diesel).) — A weak or failing battery is the most common cause of P0603, as it fails to provide the stable voltage needed to maintain the Keep Alive Memory.
  Trusted brands: ACDelco, Optima, Duralast, DieHard
  OEM price range: $200-$300
  Aftermarket price range: $150-$250
• Battery Terminal Ends/Clamps — If the original terminals are too corroded to clean or have stretched and will no longer tighten properly, they must be replaced to ensure a solid connection.
  Trusted brands: Dorman, ACDelco
  OEM price range: $15-$30
  Aftermarket price range: $5-$20

Related Codes That Often Appear With This One

• P0700 — This is a generic 'Transmission Control System Malfunction' code. It often appears alongside other transmission-related codes, indicating that the TCM has requested the check engine light be turned on. A P0603 in the TCM can trigger a P0700.
• P0601 — This is an 'Internal Control Module Memory Check Sum Error,' a more serious internal module fault. The provided TSB #PIP4653E lists them together as potential related codes.
• P0604 — This is an 'Internal Control Module Random Access Memory (RAM) Error,' also related to module memory and listed in TSB #PIP4653E.
• P1621 — This is a GM-specific code for 'Control Module Long Term Memory Performance,' directly related to the KAM function and also cited in TSB #PIP4653E.

Technical Service Bulletins (TSBs) & Recalls

• PIP4653E: Mentions that DTCs P0601, P0603, P0604, P062F or P1621 may be found stored in the Transmission Control Module. This bulletin directs technicians to ensure the codes are set in the TCM and to follow specific diagnostic procedures, reinforcing that this code often relates to transmission behavior.
• 05-06-04-060A: An informational bulletin about various control module DTCs, including P0603, which can be shared in multiple modules. This TSB highlights that a power/ground issue can cause this code to appear in the ECM, TCM, or other modules simultaneously.

Platform-Specific Known Issues

• Dual Battery Failure on Duramax Models: Owners on forums like 'dieselplace.com' frequently report that P0603 appears when one of the two batteries on a Duramax begins to fail. Even if the truck starts, the voltage drop is enough to reset KAM. The consensus repair is to always replace both batteries as a matched pair to ensure system stability.
• Corroded or Broken Engine/Body Ground Straps: A well-documented issue on GMT900 trucks is the corrosion of ground straps. A specific ground from the passenger-side rear of the engine to the firewall is often cited as a culprit for various electrical gremlins, including P0603. Owners have fixed issues by cleaning or replacing this strap.
• Harsh Shifting After Code Appears: Multiple owners report that the most noticeable symptom of P0603 is harsh or erratic transmission shifting. This is because the Transmission Control Module (TCM) loses its learned shift adaptations and reverts to its base programming. The provided TSB #PIP4653E confirms the code can be stored in the TCM.

Mechanic-Grade Diagnostic Values

• Parasitic Draw — expected: Less than 50 milliamps (0.05A) after all modules go to sleep (can take up to 30 minutes).. Failure: A sustained draw above 50mA indicates a component or module is not shutting down, draining the battery and causing low voltage on startup.
• Keep Alive Memory (KAM) Power at PCM Connector — expected: Constant battery voltage (approx. 12.6V with key off) on the specific KAM power pin(s).. Failure: Zero or fluctuating voltage indicates a break in the wiring or a blown fuse between the battery/fuse block and the module.
• Ground Circuit Voltage Drop — expected: Less than 0.2 Volts (200mV) when measured between the negative battery post and the engine block or chassis while the engine is running.. Failure: A reading higher than 0.2V indicates high resistance in a main ground cable or connection point, which can cause intermittent power loss to modules.

Scan Tool Commands That Help

• GM Tech2 / GDS2: Module Diagnostics > [Select Module] > Clear DTCs — This is the standard function to clear the P0603 code after a repair. It's important to use a tool that can see which module set the code (e.g., ECM, TCM) as noted in TSB #05-06-04-060A.
• GM Tech2 / GDS2 with TIS2Web: Service Programming System (SPS) > Reprogram ECU — Used as a last resort if the module is determined to be faulty or requires a software update to resolve a known bug. This process flashes the module with the latest GM calibration and requires a stable power supply (battery charger) to prevent bricking the module.
• High-end Aftermarket Scanners (e.g., Autel, Snap-on): Special Functions > KAM Reset — Some aftermarket tools offer a specific KAM reset function. This is a quick way to erase the adaptive memory after a repair (like fixing a vacuum leak) without clearing all DTCs or reflashing the entire module.

Wiring & Ground Locations

• G103 / G104 — G104 is on the front of the left (driver's side) cylinder head. G103 is often cited as being on the right rear of the engine block on older models, but on GMT900s, the critical engine grounds are typically on the cylinder heads.. These are primary engine-to-harness ground points. The ECM/PCM relies on a solid ground connection through these points. Corrosion or looseness here can cause intermittent KAM loss and set a P0603.
• G107 — Located on the top left rear of the engine (for 4.3L V6) or as part of the main negative battery cable assembly on the left front of the engine block for V8s.. This is a major battery ground connection point for the engine block. High resistance here from corrosion or looseness directly impacts the stability of the entire electrical system.
• Body-to-Engine Ground Strap — There are typically braided ground straps from the rear of the cylinder heads to the firewall on both the driver's and passenger's sides. The passenger side strap is a frequently cited point of failure.. These straps ensure the engine and body have the same ground potential. A broken or corroded strap can cause electrical noise and voltage differentials that lead to various module errors, including P0603.
• Underhood Fuse Block (UBEC) — Located on the driver's side of the engine bay.. This is the central distribution point for power to most vehicle modules, including the constant power for KAM. The main 175A mega fuse and the internal connections of the fuse block itself can corrode, causing voltage drops to the PCM/TCM.

Real Owner Repair Stories

• Forum user reports, synthesized from multiple threads (2008 Chevrolet Silverado 2500HD Duramax) — P0603 code present, harsh shifting, intermittent no-start (clicking solenoid).
  ❌ Tried (didn't work) Replaced both batteries with new, high-quality AGMs., Cleaned all battery terminals and main ground straps., Replaced alternator.
  ✅ What actually fixed it The main power feed wire from the 175A mega fuse to the underhood fuse block had hidden corrosion at the fuse block connection. Replacing the corroded positive cable assembly and cleaning the fuse block terminals resolved the voltage drop and eliminated the code.
• Reddit user r/MechanicAdvice (2008 Chevrolet Silverado 5.3L) — Massive parasitic draw (~2.5A), dead battery overnight, random electrical issues while driving (doors locking/unlocking, gauges failing). P0603 was likely present due to battery drain.
  ❌ Tried (didn't work) Replaced battery., Checked alternator (tested good)., Pulled fuses one-by-one to isolate the draw (radio was pulling 1A, but another 1.5A was unaccounted for)., Added extra ground wire from body to block.
  ✅ What actually fixed it While the user's final fix wasn't posted, the high parasitic draw points to a module failing to go to sleep or a short circuit. A common cause for the 1A radio draw is a faulty factory amplifier or a problem with the radio itself. The remaining draw would require further diagnosis of other modules like the BCM or a stuck relay.

Model Year Variations Within This Range

• 2007-2011: A recall was issued for some 2007-2011 HD models because the owner's manual did not specify a maximum amperage for the auxiliary battery feed to a trailer. An overload could melt a fusible link under the hood, potentially causing a fire or other electrical issues that could trigger codes like P0603. Dealers were instructed to inspect and provide the correct information.
• 2007.5-2010: The 2007 model year was a transition. This article applies to the 'new body style' GMT900 platform trucks introduced in 2007, sometimes called 2007.5. The older 'Classic' GMT800 models have different ground locations and electrical architecture.