P0602 on 2007-2014 GMC Yukon: Control Module Programming Error Explained

What's Unique About the 2007-2014 Gmc YUKON

On this generation of GMC Yukon and its GM siblings (like the Tahoe and Silverado), the P0602 code is a known issue acknowledged by GM. Technical Service Bulletin #05-06-04-060A points out that this code, along with several other module-related codes, can be set in various computers throughout the vehicle, not just the main engine computer. This means the error could originate in the Transmission Control Module (TCM), Fuel Pump Control Module (FPCM), or Body Control Module (BCM), requiring a more thorough diagnostic approach than just focusing on the ECM. For example, a failing FPCM, which is notoriously prone to corrosion as it's mounted on the frame rail, can trigger a P0602 in the ECM.

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
• Vehicle will not start or has a crank-no-start condition
• Reduced engine power or 'limp mode'
• Harsh or erratic automatic transmission shifting
• Engine may stall or idle roughly
• Noticeable decrease in fuel economy
• Cooling fans run constantly, even with the engine off, draining the battery
• Service Stabilitrak/Traction Control message on the dash

Most Likely Causes

1. Low Battery Voltage or Poor Connections 🔴 High Probability Control modules in all modern vehicles are sensitive to voltage. A weak battery, failing alternator, or corroded ground straps can cause voltage drops during startup that corrupt the module's temporary memory. GMT900 trucks have several key ground points that are known to corrode, including the main engine-to-firewall strap and grounds on the frame rail.
   How to confirm: Test the battery with a multimeter and a load tester; it should read at least 12.6 volts at rest and hold voltage under load. Check that battery terminals are clean and tight. Inspect the main ground points: battery to frame, engine block to firewall (braided strap on the back of the passenger side cylinder head), and the PCM ground on top of the engine block. A voltage drop test on these connections is the most definitive method.
   Typical fix: Charge or replace the battery. Clean or replace battery terminals and ground straps. A popular preventative measure is the 'Big 3' wiring upgrade, which improves the main power and ground cables. 🎬 See how to clean and maintain critical GM ground points.
   Est. part cost: $10-$300
2. Interrupted or Failed Module Programming 🟡 Medium Probability This often happens if a previous repair involved an attempt to update or 'flash' a module and the process was interrupted (e.g., tool disconnected, loss of power from a weak battery maintainer).
   How to confirm: This is diagnosed by attempting to reprogram the module. If the reprogramming is successful and the code disappears, this was the cause. A professional scan tool is needed to check the module's software calibration and VIN.
   Typical fix: The affected control module must be successfully reprogrammed using a GM-compliant J2534 pass-thru tool and a subscription to GM's Service Programming System (SPS).
   Est. part cost: $0
3. Faulty Engine Control Module (ECM) ⚪ Low Probability The E38 and E67 ECMs used in this generation are mounted in the hot engine bay and are known to suffer from internal failures over time due to heat cycles, which can cause cold solder joints on the main processor. This can lead to intermittent no-start conditions that are difficult to diagnose.
   How to confirm: This is the conclusion after ruling out all other possibilities. If the battery is good, connections are clean, and the module repeatedly fails to be reprogrammed, the module itself is condemned.
   Typical fix: Replace the ECM. The new module must be programmed with the vehicle's specific VIN and calibration files. Many specialists offer pre-programmed or 'cloned' ECMs.
   Est. part cost: $300-$800

Rare But Worth Checking

• Aftermarket Performance Tune: If you have an aftermarket engine tune or 'chip' installed (e.g., from DiabloSport), it may have corrupted the factory software or be incompatible, causing the P0602 code. Reverting to the stock tune often resolves the issue, though sometimes the code persists until a dealer reflash is performed.
• Incorrectly Installed Used Module: A used ECM from another vehicle will not work unless it is properly 'unlocked' and reprogrammed with your Yukon's specific VIN. It will store a P0602 code until this is done.
• Faulty Fuel Pump Control Module (FPCM): On GMT900 trucks, the FPCM is mounted to the frame rail under the vehicle and is highly susceptible to corrosion from road salt and moisture. A failing FPCM can set a P069E code and request the ECM to set a P0602. A visual inspection of the FPCM and its connector is recommended.

Diagnosis Steps

1. Check Battery Health & Charging System: Using a multimeter and load tester, ensure the battery has at least 12.6 volts and can hold a load. Start the engine and check that the alternator is charging correctly (typically 13.7 to 14.7 volts).
2. Inspect Power and Ground Connections: Thoroughly clean the battery terminals. Inspect and clean the main chassis and engine ground connections. Key locations on the GMT900 platform include the braided strap from the rear of the passenger cylinder head to the firewall, the main battery ground to the frame, and the PCM ground on the engine block.
3. Scan All Modules: Use a professional-grade scanner (not a basic code reader) capable of communicating with all vehicle modules (ECM, TCM, BCM, FPCM, etc.). Document all codes, then clear them. See which codes return immediately.
4. Attempt Reprogramming: If the code returns and points to a specific module, the next step is to re-flash it with the latest factory software. This requires a J2534 pass-thru device and a subscription to GM's online service (TIS2Web/ACDelco TDS). This is a task for a dealer or qualified independent shop.
5. Inspect Modules and Connectors: If reprogramming fails, visually inspect the suspect module (e.g., ECM, FPCM) and its connectors for any signs of corrosion, bent pins, or physical damage. The FPCM on the frame rail is particularly vulnerable.
6. Replace the Control Module: If all previous steps fail, the control module has an internal hardware fault and must be replaced. The new module will require programming to the vehicle's VIN.

Parts You'll Likely Need

• Engine Control Module (ECM) (OEM #ACDelco E38 or E67 (Varies by engine/year)) — This is the part that is replaced if the internal programming error cannot be fixed by a re-flash, indicating a hardware failure. The E38 (for 4.8L/5.3L) and E67 (for 6.0L/6.2L) are known to have heat-related failures.
  Trusted brands: ACDelco
  OEM price range: $400-$800
  Aftermarket price range: $250-$500
• Battery — A weak or failing battery is a primary cause of voltage-related memory corruption in the ECM that triggers a P0602 code.
  Trusted brands: ACDelco, DieHard, Interstate
  OEM price range: $200-$300
  Aftermarket price range: $150-$250
• Fuel Pump Control Module (FPCM) (OEM #ACDelco 20759945 (example part number, verify by VIN)) — A common point of failure on these trucks due to corrosion. A faulty FPCM can request the ECM to set a P0602 code.
  Trusted brands: ACDelco, Bosch, Dorman
  OEM price range: $80-$150
  Aftermarket price range: $60-$120

Related Codes That Often Appear With This One

• P0601 — This code means 'Internal Control Module Memory Check Sum Error'. It's a very similar internal fault and is often grouped with P0602 in diagnostic procedures.
• P0603 — This code means 'Internal Control Module Keep Alive Memory (KAM) Error'. It often points to power supply issues, as the KAM is lost when battery power is disconnected or unstable.
• U0100 — This code means 'Lost Communication With ECM/PCM'. If the ECM is failing internally due to the issues causing P0602, it may also stop communicating with other modules on the vehicle's network.
• P069E — This code means 'Fuel Pump Control Module Requested MIL Illumination'. This is a strong indicator that the P0602 code is being caused by a fault within the FPCM, not the ECM itself.

Technical Service Bulletins (TSBs) & Recalls

• 05-06-04-060A: An informational bulletin for technicians about various control module DTCs (P0601, P0602, P0603, etc.) that can be set in multiple different modules on the vehicle.
• 09-06-04-026W: An informational bulletin regarding the importance of verifying ECM calibrations before replacing major powertrain components, which is relevant when diagnosing module-related codes that could be caused by aftermarket tunes.

Platform-Specific Known Issues

• GM issued Technical Service Bulletin #05-06-04-060A, which is an informational bulletin for technicians regarding a group of control module codes including P0602. It notes that these codes can be shared across multiple modules, which is an important diagnostic consideration for this platform.
• The Fuel Pump Control Module (FPCM), located on the frame rail near the spare tire, is a well-documented weak point on GMT900 trucks. It is exposed to the elements and often fails due to corrosion, leading to a variety of codes including P069E and P0602.
• The primary engine ground strap, a braided cable from the back of the passenger-side cylinder head to the firewall, is another common failure point. Corrosion or breakage here can cause a host of difficult-to-diagnose electrical gremlins, including module programming errors.

Mechanic-Grade Diagnostic Values

• ECM/PCM Battery Positive Voltage — expected: Should be equal to battery voltage (approx. 12.6V with key on, engine off).. Failure: Low or no voltage indicates a problem with the power supply circuit to the ECM.
• ECM/PCM Ignition 1 Voltage — expected: Should be equal to battery voltage when the ignition is in the 'ON' or 'RUN' position.. Failure: Low or no voltage indicates a problem with the ignition switch or related wiring.
• CAN Bus Voltage — expected: Approximately 2.5V on both CAN High and CAN Low lines when the bus is idle.. Failure: Voltages that are stuck high, low, or do not mirror each other during communication can indicate a short or open in the harness.
• Ground Point Voltage Drop — expected: Less than 0.1 volts (100mV) between the ground point stud/bolt and the negative battery terminal.. Failure: Voltage higher than 100mV indicates high resistance in the ground connection, which can cause module communication issues.

Scan Tool Commands That Help

• GM GDS2 / Techline Connect: Module Reprogramming (SPS) — This is the primary function used to fix a P0602 code when it's caused by a software glitch or an interrupted update. It re-flashes the module with the latest factory calibration.
• GM GDS2: Module Status / DTC Display — Used as the first step to see which modules on the network are reporting 'No Communication' or setting codes. This helps determine if the P0602 is isolated to the ECM or if it's a symptom of another module's failure (like the FPCM).
• HP Tuners VCM Editor: Read/Write Calibration — Used in the aftermarket tuning world to read the existing tune file, check for corruption, or write a stock file back to the ECM to eliminate a bad tune as the cause of the P0602.

Wiring & Ground Locations

• G101 — On the left side of the engine near the generator (alternator).. This is a primary ground point for the Engine Control Module (ECM) and Transmission Control Module (TCM). High resistance here can cause a wide range of module and communication errors, including P0602.
• G103 — On the front of the passenger side (right) cylinder head.. This is another critical engine ground. On some forum posts, this specific ground being loose or corroded has been identified as a cause for intermittent drivability issues.
• G108 — A braided ground strap located on the back side of the passenger (right) cylinder head, connecting to the firewall.. This ground strap is crucial for providing a clean ground path between the engine and the chassis/body. Corrosion or breakage of this strap is a very common cause of difficult-to-diagnose electrical issues on GMT900 trucks.
• ECM Connector X1, Pin 20 (RD/WH wire) — The main 73-pin connector on the Engine Control Module.. This is the main Battery Positive Voltage feed to the ECM. Verifying stable voltage at this pin is a critical step to rule out power supply issues before condemning the module.
• FPCM Connector — On the Fuel Pump Control Module, mounted to the driver's side frame rail, typically near the spare tire.. This connector is exposed to the elements and is a common failure point due to corrosion. A bad connection here can cause the FPCM to fail and request the ECM to set a P0602.

OEM Part Supersession History

• 15213110, 25854536, 25967325, and others → 20759945 — GM consolidated multiple older part numbers into a single updated module for service replacement.
  Heads up: The FPCM for 2010 and newer models often uses a different part number (e.g., 20898936) and is not interchangeable with the earlier module. Always verify the correct part number by VIN.

Model Year Variations Within This Range

• 2007-2009 vs 2010-2014: The Fuel Pump Control Module (FPCM) part number and potentially its internal logic changed around the 2010 model year. For example, part number 20759945 is commonly used for 2007-2009 trucks, while later years may use numbers like 20791901 or 20898936. The modules are not backward or forward compatible, and the correct one must be programmed for the vehicle's VIN.