U0140 on 2010-2017 GMC Terrain: Lost Communication With Body Control Module

What's Unique About the 2010-2017 Gmc TERRAIN

For the first-generation GMC Terrain and its platform-mate, the Chevrolet Equinox, the U0140 code is specifically called out in General Motors Technical Service Bulletin (TSB) #PIT5427B. This bulletin directs technicians to inspect a particular 16-pin electrical connector known as X411 for corrosion or damage when a U0140 code is present. The connector is located under the rear of the vehicle, to the left of and behind the fuel tank. Its exposed location makes it susceptible to water and road salt, leading to corrosion. This TSB makes a wiring or connector fault a highly probable cause, potentially saving owners from the unnecessary expense of replacing the Body Control Module itself.

Diagnostic Flowchart

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

Symptoms You May Notice

• Malfunctioning power windows or door locks.
• Interior or exterior lights behaving erratically, flickering, or not working at all.
• Wipers operating incorrectly or not responding.
• Multiple warning lights on the dashboard, such as Check Engine, ABS, Service Stabilitrak, or Traction Control.
• Key fob remote may stop working.
• In some instances, the vehicle may not start.
🎬 Watch: Troubleshooting a GMC that won't start due to communication loss.
• Service Power Steering message on the Driver Information Center (DIC).
• Service AWD message on the DIC.

Most Likely Causes

1. Corroded or Damaged X411 Connector 🔴 High Probability This specific connector is identified in GM Technical Service Bulletin #PIT5427B as a common failure point for a group of communication codes, including U0140. Its location under the rear of the vehicle makes it vulnerable to water, salt, and debris, leading to corrosion.
   How to confirm: Locate the X411 connector under the rear of the vehicle, behind and to the left of the fuel tank. Disconnect it and visually inspect the pins and wiring for any signs of green or white corrosion, bent pins, or physical damage to the connector housing or wires.
   Typical fix: Clean the connector terminals thoroughly with electrical contact cleaner. If corrosion is severe or pins are damaged, the affected terminals or the entire connector pigtail may need to be replaced. Dielectric grease should be applied upon reassembly to prevent future moisture intrusion.
   Est. part cost: $10-$50
2. Wiring Harness Issues 🟡 Medium Probability Wiring harnesses can become damaged over time from vibration, heat, or chafing against other components, leading to shorts or open circuits. Another TSB, #PIT5171B, notes that internal wire breaks have been found in the harness near the X411 connector, sometimes caused by rodents.
   How to confirm: Visually inspect the wiring harness leading to and from the BCM and around the X411 connector for any signs of damage. A multimeter would be needed to check for continuity and shorts to ground on the CAN bus wires.
   Typical fix: Repair the damaged section of the wire. In severe cases, a portion of the harness may need to be replaced.
   Est. part cost: $5-$100
3. Poor Power or Ground Connection to BCM 🟡 Medium Probability
   How to confirm: Check that the battery is fully charged and that the battery terminals are clean and tight. The BCM is located under the driver's side dash. Inspect the main ground connections for the BCM, such as G210 (on the left side of the dash), to ensure they are clean, tight, and free of corrosion. Use a multimeter to verify 12V+ power and less than 0.1 Ω resistance on the ground circuit at the BCM connector.
   Typical fix: Clean and tighten ground connections. Replace a weak or failing battery. Check BCM-related fuses in the passenger side interior fuse panel. 🎬 See this guide to locate BCM fuses and relays.
   Est. part cost: $0-$250
4. Failed Body Control Module (BCM) ⚪ Low Probability
   How to confirm: This should be the last resort after all wiring, connector, and power/ground issues have been definitively ruled out. A professional scan tool would be used to attempt direct communication with the BCM; if it's unresponsive and all inputs are good, the module is likely faulty. Visual inspection of the BCM for water damage or a burnt smell can also indicate failure.
   Typical fix: Replace the Body Control Module. The new BCM will need to be programmed to the vehicle's VIN and specific options using specialized equipment.
   Est. part cost: $250-$500

Rare But Worth Checking

• Interference from Aftermarket Accessories:

Diagnosis Steps

1. Verify the battery is fully charged (12.2-12.8V) and the terminals are clean.
2. Check all fuses related to the BCM. On the Terrain, these are primarily in the interior fuse box on the passenger side center console.
3. Using a capable scan tool, check for codes in all other modules. Note which modules are reporting a loss of communication with the BCM.
4. Locate and carefully inspect the X411 connector under the rear of the vehicle (behind and left of the fuel tank) for any signs of corrosion, water intrusion, or damaged pins, as recommended by TSB #PIT5427B.
5. If the X411 connector is clean, locate the BCM under the driver's side dash. Inspect its connectors for similar signs of damage or corrosion.
6. If connectors look clean, perform a visual inspection of the wiring harness near the BCM and X411 for any chafing or damage.
7. If no visual faults are found, a professional should perform network diagnostic tests, such as checking CAN bus resistance (typically ~60 Ohms between pins 6 and 14 of the DLC).
8. Verify power and ground circuits at the BCM connector using a multimeter.
9. If all wiring and network tests pass, the BCM itself is the likely suspect and may require replacement and programming.

Parts You'll Likely Need

• Connector Pigtail or Terminals (OEM #e.g., ACDelco 84941154, 88862223) — If the X411 connector is corroded, individual wire terminals or the entire connector pigtail often need to be replaced.
  Trusted brands: ACDelco, Dorman
  OEM price range: $5-$15 per terminal, $30-$60 for pigtail
  Aftermarket price range: $2-$10 per terminal, $20-$40 for pigtail
• Body Control Module (BCM) (OEM #Varies by year/options, e.g., 23295925, 23415395) — This is replaced only after all wiring, connector, and power/ground issues have been ruled out.
  Trusted brands: ACDelco (GM Genuine)
  OEM price range: $300-$500
  Aftermarket price range: $200-$400 (often remanufactured)

Related Codes That Often Appear With This One

• U0073 — Control Module Communication Bus "A" Off
• U0100 — Lost Communication with ECM/PCM
• U0101 — Lost Communication with TCM
• U0121 — Lost Communication with Anti-Lock Brake System (ABS) Control Module
• C0045 — Left Rear Wheel Speed Sensor Circuit (related to X411 harness)
• C0050 — Right Rear Wheel Speed Sensor Circuit (related to X411 harness)

Technical Service Bulletins (TSBs) & Recalls

• PIT5427B: Directs technicians to inspect the X411 connector (located under the rear of the vehicle, behind and to the left of the fuel tank) for damage or corrosion when U0140 is stored along with a host of other communication and system codes.
• PIT5171B: Warns of intermittent communication issues due to internal wire breaks within the harness near the X411 connector, sometimes caused by rodents.
• PIT4730B: A general diagnostic tip for U0140/U0073 across many GM vehicles, advising against immediate BCM replacement and recommending thorough network diagnostics first.
🎬 Watch: A breakdown of common causes and fixes for U0140.

Platform-Specific Known Issues

• Per TSB #PIT5427B, the X411 connector is a known weak point that can cause U0140 and other communication codes due to corrosion or damage. Its location under the rear of the vehicle exposes it to the elements.
• TSB #PIT5171B also points to the harness near X411, noting that wires can break internally within the insulation, making the damage invisible without carefully checking continuity or physically manipulating the harness.

Mechanic-Grade Diagnostic Values

• CAN Bus Network Resistance — expected: ~60 Ω (Ohms) when measured between Pin 6 (CAN High) and Pin 14 (CAN Low) of the OBD-II diagnostic connector with the battery disconnected.. Failure: A reading of ~120 Ω indicates a break in one of the CAN bus circuits or a missing termination resistor. A reading significantly below 60 Ω (e.g., 0-5 Ω) indicates a short circuit between the CAN High and Low wires.
• BCM Power Supply Voltage — expected: 12.2V - 12.8V with key on, engine off. 13.7V - 14.7V with engine running.. Failure: Voltage below 12V with the engine off suggests a weak battery. Voltage below 13.2V with the engine running indicates a charging system problem. The BCM may reset or go offline if voltage drops below ~9V.
• BCM Ground Circuit Resistance — expected: < 0.1 Ω (Ohms) between the BCM ground pin and a clean chassis ground point.. Failure: Resistance higher than 0.1 Ω indicates a poor ground connection, which can cause intermittent module operation and communication faults.

Hidden / Shadow Codes Worth Checking

• Symptom Bytes (e.g., 00, 5A, 71): GM vehicles often append a two-character hexadecimal 'symptom byte' to a primary DTC. This provides more specific information about the nature of the fault. For example, TSBs related to U0140 also list codes like C0710 with symptom 71 or C0196 with symptom 5A, which can help a technician pinpoint the exact failure condition (e.g., signal invalid, circuit open). (see via A professional scan tool like the GM GDS2/Tech2 is required to view these symptom bytes; they are typically not displayed by basic OBD-II code readers.)

Scan Tool Commands That Help

• GM GDS2 (Global Diagnostic System 2): BCM Programming (SPS - Service Programming System) — This function is mandatory when replacing the BCM. A new module is blank and must be programmed with the vehicle's VIN, RPO codes (options), and security information using GM's online TIS2Web service.
• GM GDS2 or equivalent professional scan tool: Key Relearn Procedure / Immobilizer Learn — After a new BCM is installed and programmed, the vehicle's keys must be relearned to the new module. The vehicle will not start until this security procedure is completed. It typically involves a sequence of 10-minute key cycles.
• Professional Scan Tool: Bidirectional Output Control — To test if the BCM is responsive, a technician can command it to activate an output, such as 'Turn on Dome Light' or 'Lock Doors'. If the BCM does not respond to the command, and its power and grounds are verified as good, it points towards an internal failure of the BCM or a complete network break.

Wiring & Ground Locations

• BCM — Under the driver's side of the dashboard, typically to the left of the steering column.. This is the module that has lost communication. All power, ground, and network wiring must be checked at its connectors.
• X411 Connector — Under the rear of the vehicle, located to the left of and behind the fuel tank.. This is the most common failure point for U0140 on this vehicle, as identified in TSB #PIT5427B. It is highly susceptible to corrosion from road salt and water, affecting multiple circuits that pass through it, including CAN bus and wheel speed sensor data.
• G210 — On the left side of the dash.. This is a primary interior ground point. A poor connection here can affect the BCM and other nearby modules.
• G301 — Under the driver's seat.. Another key ground point for components in the passenger compartment. Corrosion or looseness can cause intermittent electrical issues.
• BCM Connector C4, Pin 26 — On the black connector (C4) at the BCM.. This is a specific ground pin for the BCM (wire is typically Black/White). It's a critical point for testing ground integrity directly at the module.
• BCM Connector C3, Pins 5 & 6 — On the light green connector (C3) at the BCM.. These are specific power input pins. Pin 5 (Brown) is accessory power, and Pin 6 (Pink) is ignition power. Verifying voltage here confirms the BCM is receiving the signal to wake up and operate.

Real Owner Repair Stories

• equinoxforum.net user report (2012 Chevrolet Equinox (platform-mate)) — Service Stabilitrak, Service Power Steering, ABS light on, multiple U-codes including U0140, U0121, U0100.
  ❌ Tried (didn't work) Replacing the battery., Checking all related fuses in the interior and under-hood fuse blocks., Visually inspecting grounds under the hood.
  ✅ What actually fixed it The owner located the X411 connector under the rear of the vehicle. Upon inspection, multiple wires were found to have green corrosion. The owner cut out the bad sections of wire, soldered in new wire, and used heat-shrink tubing to seal the repairs. After the repair, all codes were cleared and did not return.

"I Checked Everything" — The Actual Cause

• A common scenario described in TSB #PIT5171B is an internal wire break within the insulation of the harness near the X411 connector. A visual inspection will reveal no damage, and a simple continuity test with a multimeter might even pass if the broken ends are touching intermittently. The fault only becomes apparent when the harness is physically wiggled or bent while performing a continuity test, revealing the hidden break.

OEM Part Supersession History

• e.g., 13574844 → N/A — Part for early models.
  Heads up: This part number is generally for 2010-2011 Terrain/Equinox models.
• e.g., 20832469, 22740631, 22782576 → 22929627 — Part consolidation and revision.
  Heads up: These part numbers are often associated with models that have the Active Noise Cancellation option. Always verify the correct part number by VIN.
• e.g., 13586273, 13584695 → 13588447 — Part consolidation and revision for later models.
  Heads up: These part numbers are generally for the facelifted models of the first generation. Using an early model BCM on a later model (or vice-versa) will likely result in feature loss or programming failure.

Model Year Variations Within This Range

• 2010-2012: The initial NHTSA TSBs (#PIT5427B, #PIT5171B) specifically call out the 2010-2012/2013 model years for the X411 connector and harness issues, suggesting the problem was most documented on these earlier vehicles.
• 2013-2017: Different BCM part numbers are used for later models (e.g., 13588447), indicating potential internal hardware or software changes from the earlier units (e.g., 13574844). While the X411 connector issue may still occur, the module itself is different.