P0604 on 2007-2010 Chevrolet Silverado 2500: Internal Memory Error Causes and Fixes

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

On the GMT900 platform, which includes the 2007-2010 Silverado 2500, this code is not just a generic module failure. GM has issued specific service bulletins acknowledging that P0604 and related internal memory codes frequently point to the Transmission Control Module (TCM). This is a crucial distinction, as it directs diagnostics toward the transmission system rather than defaulting to the main Engine Control Module (ECM). The TCM (for Allison transmissions) or TEHCM (Transmission Electro-Hydraulic Control Module, for 6L80/90 transmissions) is prone to failure from heat cycles and vibration, leading to internal solder joint degradation. Owners often report transmission-related symptoms, and the failure can be heat-related, appearing after the truck has been running for a while.

Diagnostic Flowchart

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

Generation note: The 2007 model year is a split between two generations. The older 'Classic' body style is the GMT800, while the new body style introduced in 2007 is the GMT900. This guide primarily applies to the GMT900 generation (late 2007-2010), for which the cited TSBs and known ground issues are most relevant.

Symptoms You May Notice

• Check Engine Light (Malfunction Indicator Lamp) is on.
• Erratic or harsh transmission shifting.
• Vehicle enters 'limp mode' (stuck in one gear).
• Intermittent stalling or sudden loss of engine power.
• No-start condition where the engine cranks but does not fire.
• Loss of the PRNDL gear indicator display.
• ABS or Traction Control lights may activate.
• "Service StabiliTrak" or "Traction Control" message on the Driver Information Center (DIC).

Most Likely Causes

1. Faulty Transmission Control Module (TCM/TEHCM) 🔴 High Probability → Shop Transmission Assembly GM TSB #PIP4653E specifically identifies the TCM as a common location for the P0604 code on this platform. The module (especially the TEHCM inside the 6L90 transmission pan) is subjected to intense heat cycles, which can lead to failure of internal solder joints and electronic components over time.
   How to confirm: Use a professional scan tool to verify the code is stored in the TCM. If a software reflash doesn't solve the issue and power/grounds are good, the module is likely faulty.
   Typical fix: Replace the Transmission Control Module or TEHCM. The new module must be programmed to the vehicle's VIN. Repair services that rebuild the original module are also available.
   Est. part cost: $200-$950
2. Low Battery Voltage or Poor Ground Connections 🟡 Medium Probability → Shop Vehicle Battery Large trucks with complex electrical systems are sensitive to voltage drops. A notorious weak point on the GMT900 platform is the main engine-to-firewall ground strap, which attaches to the rear of the driver's side cylinder head at a point labeled G104. Corrosion here can cause a wide range of intermittent electrical issues, including module memory errors.
   How to confirm: Test the battery to ensure it's above 12.4V at rest and doesn't drop below 9.6V during cranking. Use a multimeter to perform a voltage drop test on the main ground cables; the reading should be less than 0.2V. Inspect and clean all battery terminals and chassis/engine ground straps, especially G104 and G103 (front of passenger side cylinder head).
   Typical fix: Charge or replace the weak battery. Clean or replace corroded terminals and ground straps. Many owners find that replacing the G104 ground strap proactively solves mysterious electrical problems. 🎬 See how to identify and maintain critical GM truck ground points.
   Est. part cost: $10-$300
3. Faulty Engine Control Module (ECM/PCM) 🟡 Medium Probability → Shop Engine Control Module (ECM) While less common than the TCM, the ECM is still a complex computer subject to failure from heat and vibration. A Reddit thread on a similar GM vehicle showed a user replacing the ECM twice for a persistent P0604, highlighting that it can be the source, though diagnosis is tricky. A YouTube repair video for a 2010 Silverado showed a P0604 code was ultimately fixed by replacing the ECM. 🎬 Watch this 2010 Silverado P0604 repair walkthrough for more details.
   How to confirm: A professional scan tool will show the P0604 code originating from the ECM. This is usually diagnosed after definitively ruling out wiring, grounds, and the TCM.
   Typical fix: Replace the Engine Control Module and program it to the vehicle. This includes performing a crankshaft position variation learn procedure.
   Est. part cost: $250-$700
4. Software/Firmware Corruption ⚪ Low Probability TSB #PIP4653E's primary diagnostic step is to attempt reprogramming the TCM, which indicates that software glitches are a known potential cause that can be fixed without hardware replacement.
   How to confirm: A dealer or qualified shop uses GM's Service Programming System (SPS) to check for and apply any available software updates to the affected module.
   Typical fix: Reprogram (reflash) the TCM or ECM with the latest factory software.
   Est. part cost: $100-$250 (Labor)

Rare But Worth Checking

• Wiring Harness Issues: While less common, a chafed or corroded wire in the harness leading to the ECM or TCM can cause voltage drops or data errors that mimic an internal module failure. On some GM trucks, the harness can rub against brackets or the shock tower. A thorough visual inspection of the harness and checking for continuity and pin fitment at the module connectors is a valid diagnostic step.

Diagnosis Steps

1. Check and record any and all stored DTCs with a professional-grade scan tool.
2. Use the scan tool to identify which specific module (ECM, TCM, etc.) has stored the P0604 code.
3. Perform a complete electrical system check. Test the battery's state of charge and perform a load test. Ensure it is above 12.4V at rest and does not drop below 9.6V during cranking.
4. Inspect and clean all battery terminals and the main power and ground connections. Pay special attention to the braided ground strap from the firewall to the rear of the driver's side cylinder head (G104) and the ground on the front of the passenger cylinder head (G103).
🎬 Watch this guide on how to replace your engine ground straps.
5. Perform a voltage drop test on the main power and ground cables between the battery and the module. The reading should be less than 0.2V. Check ground resistance to the chassis, which should be less than 0.1 Ω.
6. Clear the DTCs and see if the code returns immediately. If it does, it suggests a hard internal module fault.
7. If the code returns, check for available software updates for the affected module. Attempt to reprogram the module as recommended by TSB #PIP4653E.
8. If reprogramming fails or is not possible, and all power/ground circuits to the module are confirmed to be good, the module itself is faulty and requires replacement.
9. After replacement, the new module must be programmed to the vehicle, and procedures like a crankshaft position variation learn may be necessary.

Parts You'll Likely Need

• Transmission Control Module (TCM/TEHCM) (OEM #24256861 (Allison TCM, superseded multiple times), 24243442 (6L90 TEHCM)) — This is the most common point of failure for a P0604 code on this platform, as identified by GM's own service bulletins and extensive owner reports.
  Trusted brands: ACDelco
  OEM price range: $400-$950
  Aftermarket price range: $200-$600
• Engine Control Module (ECM) (OEM #12628641 (For 6.6L Duramax, hardware family 12609441)) — If diagnostics rule out the TCM and wiring, the ECM is the next most likely component to have failed internally.
  Trusted brands: ACDelco, Bosch
  OEM price range: $450-$700
  Aftermarket price range: $250-$550
• Engine Ground Strap

Related Codes That Often Appear With This One

• U0101 — Means 'Lost Communication With TCM'. It's common with P0604 as the internal TCM failure causes it to stop communicating on the vehicle's network.
• P0601 — An 'Internal Control Module Memory Check Sum Error'. It's another internal fault code, and GM groups it with P0604 in TSB #PIP4653E, pointing to a similar root cause.
• P0603 — An 'Internal Control Module Keep Alive Memory (KAM) Error'. This often points to power supply issues like a bad battery or ground connection, which can also trigger P0604.
• P1621 — A GM-specific code for 'Control Module Long Term Memory Performance'. It is also mentioned in TSB #PIP4653E as a related code that can be set in the TCM.

Technical Service Bulletins (TSBs) & Recalls

• PIP4653E: Addresses DTC P0604 and others being stored in the Transmission Control Module (TCM) and recommends verifying the module before diagnosis.
• 05-06-04-060A: Informs technicians that P0604 is one of several internal module fault codes that can be shared among different control modules.

Platform-Specific Known Issues

• TSB #PIP4653E: General Motors issued this bulletin for a wide range of vehicles, including the 2008-2015 Silverado, noting that DTCs P0601, P0603, P0604, P062F, or P1621 may be stored in the Transmission Control Module (TCM). It advises technicians to confirm which module set the code before starting repairs and to attempt a software reprogram as a first step.
• TSB #05-06-04-060A: This informational bulletin explains that P0604 is part of a family of internal control module DTCs that can be shared across multiple modules, emphasizing the need for careful diagnosis and checking for systemic issues like bad grounds before replacing components.
• Forum Discussion on Persistent P0604: A thread on Reddit's r/MechanicAdvice for a 2009 GM truck details a user's struggle with a P0604 code that returned immediately even after replacing the ECM with a dealer-flashed unit, disconnecting aftermarket electronics, and verifying grounds. This highlights how difficult the code can be to trace, sometimes pointing to obscure wiring issues or even repeat bad-out-of-the-box replacement modules. URL: reddit.com/r/MechanicAdvice/comments/16f0j8n/p0604_will_not_go_away/

Mechanic-Grade Diagnostic Values

• Module Ground Resistance — expected: Below 0.1 Ω. Failure: A reading higher than 0.1 Ω indicates a poor ground connection that can cause module errors.
• Battery Voltage During Cranking (at module) — expected: Above 9.6V. Failure: Voltage dropping below this level can cause a 'brown-out' condition, corrupting module RAM.
• Charging System Voltage (Engine Running) — expected: 13.5V - 14.8V. Failure: Voltage outside this range indicates an alternator or regulator issue that can damage control modules.
• Voltage Drop on Power/Ground Cables — expected: Less than 0.2V. Failure: A reading higher than 0.2V indicates excessive resistance in the cable or at the connection points.

Scan Tool Commands That Help

• GM Tech 2 / GDS2: Crankshaft Position Variation Learn — Required after replacing the ECM to calibrate the crankshaft position sensor to the new module, preventing misfire codes and ensuring accurate timing.
• GM Tech 2 / GDS2: Module Setup > Idle Learn Reset — Used after replacing the ECM to relearn the engine's idle characteristics. This is a required step to prevent idle-related codes after replacement.
• GM Tech 2 / GDS2: Theft Deterrent Relearn — Necessary after replacing the ECM to synchronize the new module with the vehicle's anti-theft system, allowing the vehicle to start.
• GM Service Programming System (SPS): Module Reprogramming — Used to flash the latest software/firmware to a control module. This is the first step recommended by TSB #PIP4653E before replacing a TCM.

Wiring & Ground Locations

• G101 — Located at the left front of the engine, lower block.. This ground point serves the Engine Control Module and Transmission Control Module.
• G103 — Located on the front of the passenger side cylinder head.. A primary engine ground point. Pass 2 identified this as a key location to inspect.
• G104 — Located on the rear of the driver's side cylinder head, often a braided strap to the firewall.. A well-known failure point on GMT900 trucks. Corrosion or breakage here can cause numerous, intermittent electrical faults, including module memory errors.
• Allison TCM 80-Way Connector — On the Transmission Control Module, located on the left front of the engine compartment, near the fan shroud.. Testing power and ground directly at the module is critical. Pin 9 (BK/WH) is a ground. Pin 10 (OG) is Battery Positive Voltage. Pin 11 (RD/BK) is Actuator Supply Voltage.

Real Owner Repair Stories

• YouTube channel 'Auto Repair Guy' (2010 Chevrolet Silverado) — Check Engine Light with code P0604.
  ❌ Tried (didn't work) Checked alternator output (was good at 14.9V)., Removed aftermarket wiring., Reprogrammed the existing ECM with updated software.
  ✅ What actually fixed it The ECM was faulty and had to be replaced. After installation, a series of learn procedures were required: Idle Learn Reset, Crankshaft Position Variation Learn, and Theft Deterrent Relearn.
• Reddit user on r/MechanicAdvice (Chevrolet Silverado with an aftermarket tune.) — Persistent P0604 that would not clear.
  ❌ Tried (didn't work) Replaced ECM with a dealer remanufactured unit and flashed it., Eliminated an aftermarket CANBUS-connected radio., Tested all fuses and relays., Checked all grounds.
  ✅ What actually fixed it The user's post is a request for help and does not have a final resolution, but it highlights that even after replacing the ECM and checking grounds, the problem can persist, possibly due to an underlying wiring issue or a problem with the aftermarket tune's interaction with the system.

OEM Part Supersession History

• 29546670 → 24256861, which was later superseded by 19434406 — Standard part updates for reliability and component changes.
  Heads up: Part number 24256861 is listed for 2009-2015 models, but there is a mid-model year break in 2015. It is critical to verify the correct part number by VIN before ordering.

Model Year Variations Within This Range

• 2007-2010: Trucks in this range could be equipped with either an Allison 6-speed (with an external TCM) or a GM 6L90 6-speed (with an internal TEHCM). The diagnostic approach is similar (check grounds/power first), but the physical location and replacement procedure for the control module are completely different. The 6L90 TEHCM is inside the transmission oil pan.
• 2007-2010 (6L90 equipped): The internal TEHCM for the 6L80/6L90 transmissions underwent several revisions during this period. Early 'Gen 1' TEHCMs are known for pressure switch and solenoid failures. Later versions had improved components. The TEHCMs are not always interchangeable between years, so the correct part must be selected based on the vehicle's year and VIN.