U0073 on 2014-2021 GMC Sierra 1500: Causes and Fixes for Communication Bus Failure

What's Unique About the 2014-2021 Gmc SIERRA 1500

The GMC Sierra from this era (K2XX and T1XX generations) is known for being sensitive to voltage and ground integrity. A specific ground point, G218, located in the driver's side kick panel/A-pillar area, is a well-documented failure point. It's prone to corrosion or having sound-deadening material caught under it from the factory, leading to a poor connection that causes widespread communication issues like U0073. 🎬 See this breakdown of the U0073 CAN bus fault code. Several manufacturer bulletins also point to issues with wiring harness chafing and logic lockups in the Serial Data Gateway Module (SDGM), confirming the platform's susceptibility to these network faults. [Bulletin #PIT5586G, #PIT5405C]

Diagnostic Flowchart

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

Generation note: This range covers the end of the third generation (K2XX; 2014-2018) and the beginning of the fourth generation (T1XX; 2019-2021). While the code's meaning is the same, the exact location of wiring chafe points and ground connections like G218 may vary slightly between these two distinct platforms. However, the diagnostic principles and the high probability of the G218 ground being the fault remain identical.

Symptoms You May Notice

• Multiple warning lights on the instrument panel (Check Engine, ABS, Stabilitrak, Service Trailer Brake).
• Instrument cluster gauges sweeping or dropping to zero while driving. [Bulletin #PIT5713A]
• Loss of electric power steering assist, wheel may jerk or kick.
• Radio, infotainment screen, and/or HVAC controls go blank or become inoperative. [Bulletin #PIT5586G, #PIT5405B]
• Engine may stall, not start, or enter a reduced power "limp mode".
• Headlights and dash lights flickering, especially when using turn signals or brakes.
• Wipers operate erratically or park in the wrong position. [Bulletin #PIT5405C]
• Scan tool fails to communicate with multiple modules.

Most Likely Causes

1. Poor Ground Connection at G218 🔴 High Probability This specific ground point is notoriously faulty from the factory. TSB #PIT5405C directly calls out that the dash insulator mat is often trapped between the ground terminal and the body, preventing a solid connection and leading to intermittent network failure.
   How to confirm: Visually inspect the ground stud located behind the driver's side kick panel, near the A-pillar. Look for the black ground wires on a stud. Check for looseness, corrosion, or, most importantly, black foam insulation material pinched under the eyelet terminal.
   Typical fix: Remove the 10mm nut, pull the wire terminals off, and cut or trim away the interfering foam insulation. Clean all contact surfaces (the terminal, the body stud, and the nut) to bare metal, re-secure it tightly, and apply dielectric grease to prevent future corrosion.
   Est. part cost: $0-$5
2. Chafed or Damaged Wiring Harness 🔴 High Probability TSBs and owner forums frequently mention wiring harnesses rubbing against sharp metal edges, particularly the main harness near the parking brake pedal assembly, under the driver's door sill plate, or where it passes through the firewall.
   How to confirm: Visually inspect the CAN bus wires (typically a twisted pair of Tan and Tan/Black wires) in common chafe locations for exposed copper, breaks, or corrosion. Pay close attention to the area around the parking brake pedal bracket.
   Typical fix: Repair the damaged section of wire using solder and heat-shrink tubing. Reroute or protect the harness with loom or high-quality tape to prevent future damage.
   Est. part cost: $5-$25
3. Weak or Failing Battery / Alternator 🟡 Medium Probability Modern control modules are highly sensitive to voltage. A drop below 12.0V during startup can cause modules to fail initialization and drop off the network, setting a U0073 code.
   How to confirm: Test the battery voltage with the engine off (should be >12.4V) and the alternator output with the engine running (should be 13.7-14.7V). Perform a load test on the battery, as a battery can show good voltage but fail under load.
   Typical fix: Replace the weak battery or faulty alternator.
   Est. part cost: $150-$600
4. Faulty Control Module ⚪ Low Probability While less common than wiring issues, any module on the network (BCM, ECM, ABS, SDGM) can fail internally and short out the entire communication bus. The BCM is a common point of failure if wiring and grounds are good.
   How to confirm: This requires an advanced scan tool to see which modules are offline. The definitive test is to unplug modules one by one until communication is restored to the others. This is a last resort after all wiring/ground checks.
   Typical fix: Replace the faulty module. Note that many modules, especially the BCM, require programming by a dealer or qualified shop after installation.
   Est. part cost: $300-$1500

Rare But Worth Checking

• Faulty Aftermarket Electronics: Poorly installed remote starters, alarms, or audio systems can interfere with or damage the CAN bus wiring, causing communication faults. If the problem started after an installation, this should be the first suspect.
• Failed Termination Resistor: The High-Speed CAN bus has two 120-ohm resistors at each end of the network. When measured in parallel, they give a total network resistance of 60 ohms. One resistor is typically inside the ECM, and the other can be in a module like the TBCM or in a harness connector near the rear of the vehicle. If one fails, the resistance will read 120 ohms, causing unstable communication.
• Blown 175-Amp Mega Fuse: A voltage spike from an improper jump-start can blow the main 175A mega fuse, located on the battery distribution block. This fuse is designed to protect all the modules. If the truck is completely dead and showing U0073 after a jump, this fuse is a primary suspect.

Diagnosis Steps

1. Verify Battery Health: Ensure the battery is fully charged (>12.4V) and passes a load test. Check that the charging system is working correctly (13.7-14.7V while running). Clean battery terminals and check main power/ground cables for tightness.
2. Scan All Modules: Use a high-quality scan tool to check for codes in ALL vehicle modules, not just the engine computer. Note which modules are not responding, as this can give clues to the location of the fault.
3. Inspect Ground G218: This is the most critical step. Locate the G218 ground stud under the driver's side dash, near the A-pillar/kick panel. Disassemble, cut away any interfering foam insulation, clean all contact points to bare metal, and securely re-fasten.
4. Inspect Wiring Harnesses: Carefully check for chafing, pinching, or corrosion on the wiring harness, especially around the parking brake pedal, under the driver's door sill, and at the firewall pass-through.
5. Check for Aftermarket Devices: If any aftermarket electronics are installed, temporarily disconnect them completely to see if communication is restored.
6. Measure Bus Resistance (Advanced): With the battery disconnected, measure the resistance between Pin 6 (CAN High) and Pin 14 (CAN Low) at the OBD-II port. A healthy network will read approximately 60 ohms. A reading of 120 ohms indicates a missing termination resistor or an open circuit in the bus. A reading near 0 ohms indicates a short circuit between the two CAN wires.
7. Isolate a Faulty Module (Advanced): If wiring and grounds are confirmed good, begin unplugging non-essential modules one at a time (e.g., radio, ABS module) and re-scanning to see if communication returns to the rest of the network. The module that, when unplugged, restores communication is the faulty one.

Parts You'll Likely Need

• Wiring Repair Supplies — Used to fix chafed or broken wires in the CAN bus harness, which is a common cause.
  Trusted brands: 3M
  OEM price range: $10-$30
  Aftermarket price range: $5-$20
• Body Control Module (BCM) (OEM #13594768 (supersedes 13593214, 13580690, 13591519, 13594769)) — If diagnosed as faulty, the BCM can bring down the entire network. This shoul
  Trusted brands: ACDelco
  OEM price range: $350-$500
  Aftermarket price range: $200-$400

Related Codes That Often Appear With This One

• U0100 — Lost Communication With ECM/PCM
• U0101 — Lost Communication with TCM
• U0121 — Lost Communication With Anti-Lock Brake System (ABS) Control Module
• U0140 — Lost Communication With Body Control Module (BCM)
• U0155 — Lost Communication With Instrument Panel Cluster (IPC) Control Module

Technical Service Bulletins (TSBs) & Recalls

• PIT5677E: Lists U0073 as one of many potential electrical system DTCs.
• PIT5713A: Connects U0073 with symptoms like IPC gauges sweeping and multiple warning messages.
• PIT5586G: Associates U0073 with steering feedback issues, inoperative HVAC, and potential logic lock of the serial data bus.
• PIT5405C / PIT5405B: Links U0073 to instrument panel/radio going blank and erratic wiper function.

Platform-Specific Known Issues

• Owner Experience: Intermittent No-Start and Instrument Cluster Failure: An owner of a 2014 Sierra reported that their truck would intermittently fail to start, accompanied by the entire instrument panel going dead and multiple warning messages like "Service Stabilitrak." After several expensive diagnostic sessions at a shop suggested replacing the BCM, the owner found a forum post about the G218 ground. By removing the driver's side kick panel, they found the ground nut was slightly loose and that factory sound-deadening insulation was caught under the terminal. After trimming the insulation and cleaning the connection with a wire brush, the problem was permanently resolved for under $5 in supplies. This is a classic example of the most common failure on this platform.

Mechanic-Grade Diagnostic Values

• CAN Bus Resistance — expected: ~60 Ω. Failure: A reading of ~120 Ω indicates an open circuit or a failed/missing termination resistor. A reading near 0 Ω indicates a short between the CAN High and CAN Low wires.
• CAN Bus Voltage (Recessive State) — expected: ~2.5 V on both CAN High and CAN Low. Failure: Significant deviation from 2.5V on either line indicates a potential short to power or ground.
• CAN Bus Voltage (Dominant State) — expected: CAN High: ~3.5 V, CAN Low: ~1.5 V. Failure: Inability to pull the lines to these voltages indicates a bus problem.
• Battery Voltage — expected: >12.4 V (engine off), 13.7 V - 14.7 V (engine running). Failure: Low static voltage or improper charging voltage can cause modules to drop off the network.

Hidden / Shadow Codes Worth Checking

• U0073 71: Control Module Communication Bus Off Invalid Data (see via A dealer-level scan tool like the GM GDS2 is required to see these specific symptom codes.)
• U0073 72: Control Module Communication Bus Off Alive Counter Incorrect (see via A dealer-level scan tool like the GM GDS2 is required to see these specific symptom codes.)

Scan Tool Commands That Help

• GM GDS2 / High-End Scan Tool: Module Communication Status — Use this function to get a list of all modules on the network and see which ones are reporting 'No Communication'. This is the first step in isolating the location of the fault.
• GM GDS2: Data Bus Diagnostic Tool — This is a guided diagnostic routine within the GM Service Information (SI) system that assists technicians in systematically diagnosing High Speed LAN issues.

Wiring & Ground Locations

• G218 (K2XX Platform, 2014-2018) — Under the driver's side dash, behind the kick panel, bolted to the A-pillar frame.. This is the most common failure point. Factory-installed sound deadening material gets trapped under the ground terminal, causing a poor connection and intermittent network failure.
• G218 (T1XX Platform, 2019-2021) — On the PASSENGER side dashboard frame, tucked up near the A-pillar.. This is a critical ground point on the newer platform. It is prone to having paint under the lug from the factory, which acts as an insulator and causes voltage instability.
• Termination Resistor (External) — On K2XX models, it is a separate component (GM Part #88988999) located in the rear of the vehicle, often taped to the main wiring harness above the spare tire and muffler area.. The CAN bus requires two 120-ohm resistors for proper communication. One is in the ECM, the other is this external resistor. If it fails or its wiring is damaged, the bus resistance will read 120 ohms instead of 60, causing communication failure.
• X225 Connector — In the passenger compartment, behind the lower left side of the instrument panel.. A GM Technical Service Bulletin (PIT5277A) identifies this as a potential location for bent or backed-out terminals causing various electrical issues on 2014-2015 models.
• 175-Amp Mega Fuse — Inside the battery distribution block, a small plastic box on or near the positive battery terminal.. This fuse protects multiple modules. A voltage spike from an improper jump-start can blow this fuse, taking the entire CAN bus offline and causing a U0073 code with a no-start condition.

Real Owner Repair Stories

• YouTube Commenter on 'G218 Ground Issue Fix' video (2014-2018 Chevy Silverado / GMC Sierra) — Unspecified electrical issues leading to hours of online searching for a ground problem.
  ❌ Tried (didn't work) Hours of Google searching
  ✅ What actually fixed it Following the video guide to locate and clean the G218 ground under the driver's side dash fixed the truck in 30 minutes.
• Reddit user in /r/Silverado (2015 Silverado 1500 with 30,000 miles) — Intermittent "Service Stabilitrak" message, with the radio and dash screens flashing. Seemed to only happen when it was raining and when turning right.
  ❌ Tried (didn't work) Initial confusion, considering checking wheel bearing sensors for water.
  ✅ What actually fixed it The top-rated solution from another user was to fix the G218 ground connection, which is a known cause for these exact symptoms.

OEM Part Supersession History

• 13580690, 13591519, 13593214 → 13594768, 13594769 — Part revision and update by the manufacturer.
  Heads up: This Body Control Module (BCM) is NOT plug-and-play. It is tied to the vehicle's security system and options. The new module must be programmed by a dealer or have the data from the original BCM 'cloned' onto it.

Model Year Variations Within This Range

• 2014-2018 (K2XX Platform): The primary G218 ground point causing this issue is located under the DRIVER'S side dash, behind the kick panel. This platform uses an external 120-ohm termination resistor in the harness at the rear of the vehicle.
• 2019-2021 (T1XX Platform): The primary G218 ground point causing this issue is located on the PASSENGER'S side A-pillar frame. Factory paint under the ground lug is the common fault. The CAN bus architecture and wiring harness routing differ significantly from the previous generation.