U0140 on 2023-2025 GMC Yukon: Lost Communication With BCM Causes & Fixes

What's Unique About the 2023-2025 Gmc YUKON

The 2023-2025 GMC Yukon is built on GM's advanced Global B electrical architecture, which is heavily reliant on network communication between various modules. This makes it particularly sensitive to communication faults. Manufacturer Technical Service Bulletins (TSBs) for GM trucks and SUVs, including models with similar architecture, point directly to two main culprits for code U0140: poor ground connections for the Body Control Module and logic or connection issues with the Serial Data Gateway Module (SDGM). The SDGM acts as a critical translator or bridge between the vehicle's different data networks, and its failure can bring down multiple, seemingly unrelated systems at once. The specific BCM ground point G218, located in the driver's footwell, is a known weak point where dash insulation can get trapped under the terminal from the factory, causing a poor connection over time.

Diagnostic Flowchart

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

Symptoms You May Notice

• Multiple warning lights on the instrument panel (e.g., ABS, traction control, Service Stabilitrak).
• Instrument panel gauges dropping to zero or screen going blank.
• Power windows, door locks, or mirrors not working.
• Interior or exterior lights malfunctioning or acting erratically.
• Radio or infotainment screen going blank or rebooting.
• No chimes or turn signal audio.
• Vehicle may not start or may stall.
• Hood ajar message or alarm sounding unexpectedly.

Most Likely Causes

1. Poor Body Control Module (BCM) Ground Connection 🔴 High Probability → Shop Body Control Module This is a well-documented issue on GM trucks and SUVs, as cited in multiple TSBs (PIT5405B, PIT5405C). TSB PIT5405C specifically notes that the dash insulator mat can get trapped under the G218 ground eyelet from the factory, causing a poor connection. This single issue is the most common fix reported by owners.
   How to confirm: Locate the primary BCM ground connection, G218, in the driver's side footwell, attached to the A-pillar body structure. 🎬 Watch: How to locate and clean the G218 ground point Visually inspect for looseness, corrosion, or trapped insulation material under the terminal. A voltage drop test across the ground point should read less than 0.1-0.2 volts.
   Typical fix: Disconnect the negative battery terminal. Remove the ground nut (typically 10mm). Cut away any interfering insulation mat. Thoroughly clean the terminal, the stud, and the chassis contact point to bare metal with a wire brush or sandpaper, and re-tighten securely.
   Est. part cost: $0-$10
2. Serial Data Gateway Module (SDGM) Fault 🔴 High Probability → Shop Telematics Interface Module TSBs (PIT5586G, PIT5586B) specifically mention issues like 'logic lock' or poor terminal connections at the SDGM, which acts as a traffic controller for the vehicle's data networks. Software updates and recalls for the SDGM are also common on these platforms as GM refines the Global B architecture.
   How to confirm: A professional scan tool is needed to check if the SDGM is communicating. A technician can inspect the X1 (black) and X2 (gray) connectors for backed-out pins or poor terminal tension as per TSB #PIT5586G. Sometimes, disconnecting the battery for 30+ minutes can reset a 'logic lock' state.
   Typical fix: The fix can range from repairing a loose terminal at the connector to performing a software update (reprogramming) or replacing the module itself. 🎬 See how the Serial Data Gateway Module affects network communication Module replacement requires programming by a dealer or qualified shop with access to GM's software.
   Est. part cost: $150-$350
3. Low Battery Voltage or Failing Alternator 🟡 Medium Probability → Shop Vehicle Battery Modern control modules are highly sensitive to voltage. A weak or failing battery can cause a multitude of unpredictable communication errors across the vehicle's network as modules drop offline when voltage dips below their operating threshold (typically ~9V).
   How to confirm: Test the battery with a digital multimeter or a battery tester. A healthy, resting battery should be at approximately 12.6 volts. With the engine running, voltage should be between 13.7 and 14.7 volts. A load test is the most definitive way to identify a weak battery.
   Typical fix: Recharge or replace the battery. If the charging voltage is low, the alternator needs to be tested and likely replaced.
   Est. part cost: $150-$400
4. Damaged Wiring or Poor Connections ⚪ Low Probability The CAN bus network wires run throughout the vehicle. Wires can be damaged from abrasion, previous repairs, or water intrusion, especially in areas like door jambs, A-pillars, or near the fuse block. Water leaks from sunroof drains or windshield seals can drip onto the BCM or its connectors.
   How to confirm: A visual inspection of the wiring harness leading to the BCM and SDGM is the first step. Checking for continuity and shorts on the CAN bus wires with a multimeter is a more advanced diagnostic step. With the battery disconnected, resistance between pins 6 and 14 of the OBD-II port should be ~60 ohms.
   Typical fix: Repairing the damaged section of the wire or cleaning and securing the corroded/loose connector. Applying dielectric grease can prevent future moisture intrusion.
   Est. part cost: $10-$100

Rare But Worth Checking

• Faulty Body Control Module (BCM): → Shop Body Control Module While the code directly points to the BCM, the module itself is often not the root cause. It's more frequently a victim of bad grounds, poor voltage, or other network issues. All other possibilities should be exhausted before replacing the BCM.
🎬 Watch: Common causes and fixes for the U0140 code
• Aftermarket Device Interference: Poorly installed aftermarket accessories like remote starters, alarms, or telematics devices that tap into the CAN bus wiring can disrupt network communication and trigger a U0140 code.

Diagnosis Steps

1. Check Battery Health: Ensure the battery is fully charged and holding a proper charge (12.6V+ resting). Load test the battery. Low voltage is a common cause of communication codes.
2. Scan for All Codes: Use a professional-grade scan tool to pull codes from all modules, not just the engine computer. Note which modules are reporting 'no communication'.
3. Inspect BCM Fuses: Check all fuses related to the Body Control Module in the interior and under-hood fuse panels.
4. Inspect BCM Ground Connection (G218): This is the most critical step. Locate the G218 ground point in the driver's side footwell, on the A-pillar structure. Disconnect the battery, then remove the ground nut. Check for trapped insulation, clean the contact surfaces to bare metal, and re-tighten securely.
5. Inspect SDGM Connections: Visually inspect the X1 and X2 connectors at the Serial Data Gateway Module (located behind the driver's lower dash) for any signs of damage, corrosion, or backed-out pins.
6. Perform a Hard Reset: Disconnect both battery cables and touch the cable ends together for 30 seconds to drain any residual power from the modules. This can sometimes clear an SDGM 'logic lock'.
7. Advanced Diagnostics (Professional): If the problem persists, use a multimeter to check CAN bus resistance at the OBD-II port (pins 6 & 14 with battery disconnected); it should be ~60 Ohms. A technician will then need to test for continuity, resistance, and voltage on the network lines using wiring diagrams to find a break or short.

Parts You'll Likely Need

• Body Control Module (BCM) (OEM #Varies by VIN and options (e.g., 84992853, 85590288 - verify with dealer)) — This is only needed if the module itself has failed internally, which is less common than wiring or ground issues. Replacement is a last resort after all other diagnostics have been performed and requires dealer programming.
  Trusted brands: ACDelco (GM Genuine)
  OEM price range: $400-$600
  Aftermarket price range: $250-$450
• Serial Data Gateway Module (SDGM) (OEM #Varies by VIN and options (e.g., 13534928 - verify with dealer)) — Needed if the module has an internal fault or a software update doesn't resolve a 'logic lock' condition. This is a likely culprit if the BCM ground is good. Requires dealer programming.
  Trusted brands: ACDelco (GM Genuine)
  OEM price range: $150-$350
  Aftermarket price range: $100-$200

Related Codes That Often Appear With This One

• U0073 — Control Module Communication Bus A Off (Another general network communication code often set with U0140, as seen in TSBs PIT5405B/C).
• U0100 — Lost Communication with ECM/PCM (Indicates a widespread network failure, often triggered by the same root cause as U0140, like a bad SDGM or ground issue, as seen in TSBs PIT5586B/G).
• U0101 — Lost Communication with TCM (Transmission Control Module). Like U0100, this points to a broader network problem, as listed in TSBs PIT5586B/G.
• U0155 — Lost Communication With Instrument Panel Cluster (IPC) Control Module (The instrument panel is a key module on the network; its failure to communicate is a common symptom and associated code, as seen in TSB PIT5586B/G).

Technical Service Bulletins (TSBs) & Recalls

• PIT5405C / PIT5405B: Details intermittent electrical issues and a host of 'U' codes, including U0140, caused by a poor BCM ground at G218. Specifically mentions the dash insulator mat being trapped under the ground eyelet.
• PIT5586G / PIT5586B: Instructs technicians to check for a 'logic lock' condition in the Serial Data Gateway Module (SDGM) or for poor terminal tension/backed-out pins in the SDGM's X1 and X2 connectors.
• PIC6607B: Advises technicians not to replace the Image Processing Module if U0140 is stored in history, preventing a common misdiagnosis.
• PIT4730B: Notes that the BCM can appear offline intermittently due to shorts on the data lines, and warns against hasty replacement.

Platform-Specific Known Issues

• TSB #PIT5405B/C: Point to checking the Body Control Module ground as a primary cause for a multitude of communication codes, including U0140.
• TSB #PIT5586B/G: Instruct dealers to check for a 'logic lock' of the Serial Data Gateway Module or for terminal concerns in its connectors when U0140 and other communication codes are present.
• TSB #PIC6607B: Explicitly warns technicians *not* to replace the Image Processing Module if U0140 is found as a history code, indicating this is a common misdiagnosis.

Mechanic-Grade Diagnostic Values

• CAN Bus Network Resistance — expected: ~60 Ohms (Ω). Failure: A reading of ~120 Ohms indicates a missing termination resistor or a break in one of the CAN lines. A reading near 0 Ohms indicates a short between the CAN High and CAN Low wires.
• BCM Ground Circuit Voltage Drop — expected: Less than 0.1 - 0.2 Volts (100-200 mV). Failure: A reading higher than 0.2V indicates excessive resistance in the ground circuit, confirming a poor connection at points like G218.
• Battery Voltage (Engine Off) — expected: ~12.6 Volts. Failure: A reading below 12.4V suggests a discharged or failing battery which can cause modules to drop off the network.
• Charging System Voltage (Engine Running) — expected: 13.7 - 14.7 Volts. Failure: Voltage below 13.7V or above 14.7V indicates a problem with the alternator or charging system.

Hidden / Shadow Codes Worth Checking

• Uxxxx SYMxx (e.g., U0140 SYM00): GM uses 'symptom bytes' (the two digits after 'SYM') to add specific details to generic 'U' codes. For example, TSB #PIC6607B lists U0140, U023B SYM00, and U3000 SYM49. These provide technician-level insight into the nature of the communication failure (e.g., 'No Communication', 'Invalid Data'). (see via These codes are typically only visible on a dealer-level scan tool like GDS2 or a high-end professional scanner that can read enhanced GM data.)

Scan Tool Commands That Help

• GDS2 (GM Global Diagnostic System 2): Module Communication Status — This function is used to view a list or network topology map of all control modules. It will clearly show which modules are actively communicating and which ones are offline (not responding), directly confirming the BCM is the source of the U0140 code.
• GDS2 (GM Global Diagnostic System 2): SDGM Reprogramming — According to GM Service Update N212353390, if the Serial Data Gateway Module (SDGM) was replaced, it may need to be reprogrammed to ensure it is correctly registered with the vehicle's network and capable of Over-The-Air (OTA) updates. This is used to fix issues after an SDGM replacement.

Wiring & Ground Locations

• G218 — In the driver's side footwell, bolted to the A-pillar body structure, often behind the plastic kick panel.. This is the primary ground for the Body Control Module. TSB PIT5405C identifies a poor connection here, often due to trapped dash insulation from the factory, as a root cause for U0140 and widespread electrical issues.
• G304 / G305 — G304 is reported on the driver's side A-pillar behind the trim, near the speaker. G305 is under the driver's side dash, near the parking brake assembly.. These are additional ground points that can affect BCM operation. While G218 is the most cited, checking these grounds is also recommended if G218 appears clean and tight.
• SDGM Connectors X1 & X2 — The Serial Data Gateway Module is located behind the driver's side lower dashboard. X1 (black) and X2 (gray) are its main connectors.. TSB PIT5586G instructs technicians to inspect these specific connectors for bent, backed-out, or loose terminals, which can cause a total network collapse and a host of communication codes, including U0140.
• OBD-II Port Pins 6 & 14 — The main diagnostic port under the driver's side dashboard.. Pin 6 is CAN High and Pin 14 is CAN Low. Measuring resistance between these two pins (with the battery disconnected) is the primary method for testing the health of the main communication network's termination resistors.

Real Owner Repair Stories

• tahoeyukonforum.com user (2015 GMC Yukon) — Radio screen going blank, no blinker sounds, multiple warning messages, gauges dropping to zero.
  ❌ Tried (didn't work) Replacing the battery, Checking all fuses
  ✅ What actually fixed it The owner found GM bulletin PIT5405, located ground point G218 in the driver's footwell, and discovered the dash insulation was interfering with the connection. Cleaning the ground and re-securing it completely resolved all symptoms.
• YouTube user Dustin Turner (2014 Silverado High Country (same platform architecture)) — Headlights and dash lights flickering/dimming, especially when turning or braking. Vehicle would completely shut off at low speeds, losing power steering assist and displaying multiple warnings like 'Park Assist Disabled'.
  ❌ Tried (didn't work) Testing the battery and alternator (both tested fine)
  ✅ What actually fixed it The problem was the G218 ground. Sound deadening material was trapped under the ground connection. Trimming the material away and cleaning the connection point permanently fixed all electrical issues.

OEM Part Supersession History

• 13520409 → 13529041 — Part revision or update by the manufacturer.
  Heads up: Replacement of the BCM requires programming and special setup procedures to ensure proper operation in the vehicle.
• 13542152, 13546980 → 13547771 — Part revision or update by the manufacturer.
  Heads up: This part is listed for Yukon models and requires programming. The description notes it may be physically labeled with a different number, such as 13547769 or 13546980.

Model Year Variations Within This Range

• 2021-2022: A service update (N212353390) was issued for 2021-2022 Yukon/Tahoe/Suburban models where a replaced Serial Data Gateway Module (SDGM) may not have been programmed correctly, preventing Over-The-Air (OTA) updates. The fix is to reprogram the SDGM. This could affect vehicles in the 2023-2025 range if they had an earlier service replacement of the SDGM.