U0131 on 2014-2020 GMC Sierra 1500: Power Steering Communication Loss Causes & Fixes

What's Unique About the 2014-2020 Gmc SIERRA 1500

On this generation of GMC Sierra and its platform mates (like the Chevy Silverado), the U0131 code is very frequently linked to specific, well-documented electrical flaws rather than an immediate failure of the expensive steering rack. GM has issued multiple Technical Service Bulletins (TSBs) pointing technicians toward a poor ground at location G218 under the dash and damaged wiring harnesses in the door sill plates as primary culprits. Many owners have successfully fixed the problem by addressing these grounding or wiring issues, which are often factory-related defects.

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, 2014-2019) and the beginning of the fourth generation (T1XX, 2019-2020). The G218 ground issue is a widely reported problem on the 2014-2018 K2XX models. A specific engine harness chafing issue is noted for 2020 models with the 2.7L engine per Service Update N192287840. A corroded chassis-to-battery ground strap behind the right front splash shield 🎬 Watch: How a corroded ground strap can kill your steering. is also a known issue on the T1XX platform.

Symptoms You May Notice

• Complete loss of power steering assist (steering feels very heavy)
• "Service Power Steering" or "Steering Assist is Reduced Drive With Care" message on the instrument panel
• Stabilitrak warning light may also illuminate
• In some cases, multiple warning lights and messages may appear due to network instability (e.g., Service ESC, Service Trailer Brake System)
• Steering wheel may jerk or kick back, especially at low speeds
• Instrument panel, radio, or HVAC displays may go blank intermittently
• Headlights and dash lights may flicker or dim, especially when turning the wheel at low speeds

Most Likely Causes

1. Poor Ground at G218 Location 🔴 High Probability A factory assembly issue where the dash insulator mat gets trapped between the ground eyelet and the chassis, preventing a solid connection. This is documented in TSB #PIT5405C 🎬 Watch: Step-by-step guide to fixing the G218 ground issue. and is a very common fix discussed by owners.
   How to confirm: Visually inspect the G218 ground stud, located under the dash on the driver's side, behind the A-pillar trim and often near the speaker. Check if the sound-deadening mat is underneath the ground wire's ring terminal. The nut may also be loose. The nut is often 10mm.
   Typical fix: Remove the nut and ground terminal, cut away or pull back the interfering insulation mat, clean the contact surfaces of the stud and eyelet with a wire brush or sandpaper to ensure bare metal contact, and securely retighten the nut.
   Est. part cost: $0-$5
2. Damaged Wiring Harness 🟡 Medium Probability TSB #PIT5457D notes that wiring harnesses under the driver and passenger sill plates can become damaged from foot traffic, moisture, or improper routing, causing communication issues with the PSCM and other modules. The communication enable circuit (5986) is often the affected wire.
   How to confirm: Remove the door sill plates and inspect the wiring channel for signs of chafing, corrosion, pinched wires, or water intrusion. Look for broken or corroded wires, particularly in splice packs.
   Typical fix: Repair any broken, corroded, or chafed wires. Ensure the harness is properly secured and protected from future damage. This may involve soldering, using quality butt connectors, and re-taping the harness.
   Est. part cost: $5-$50
3. Low System Voltage or Blown Fuse 🟡 Medium Probability The electric power steering motor draws significant current. A weak battery, failing alternator, or poor battery cable connections can cause voltage drops that trigger communication faults. Some owners report a bad battery cell was the root cause.
   How to confirm: Test the battery and charging system. Ensure battery voltage is above 12.6V with the engine off and between 13.8-14.4V when running. Inspect the main high-amperage fuse (often 80A or a 175A mega fuse) for the power steering system, located in a fuse box on the positive battery terminal or in the main under-hood fuse box. 🎬 See this video to locate your power steering fuse and relay. TSB #PIT5405C also advises checking battery cable connections at the battery, engine block, and fuse block for tightness and corrosion.
   Typical fix: Replace a weak battery, repair charging system issues, or replace the blown fuse after diagnosing the cause of the overcurrent. Clean and tighten all battery cable connections.
   Est. part cost: $10-$350
4. Failed Power Steering Control Module (PSCM) / Steering Rack ⚪ Low Probability While less common than wiring/ground issues, the module itself can fail internally. On these trucks, the PSCM is integrated with the electric power steering rack assembly, making it a single, expensive part.
   How to confirm: This is a diagnosis of exclusion. If all power, ground, and communication network wiring (CAN bus) have been tested and confirmed to be good, the PSCM is the likely point of failure. A professional scan tool is needed to confirm the module is truly offline and not responding.
   Typical fix: Replace the entire electric power steering rack and pinion assembly. The new module will require programming (calibration) to the vehicle using specialized software like GM's SPS.
   Est. part cost: $800-$2000

Rare But Worth Checking

• Engine Harness Chafe (2.7L Engine): Service Update N192287840 was issued for some 2020 models with the 2.7L Turbo engine for an engine wiring harness that could chafe on various engine and chassis components. This can cause shorts to ground and various issues including communication codes and stalling.
• Corroded Main Chassis Ground Strap: On newer T1XX models (2019+), a braided ground strap from the chassis to the battery, located behind the right front splash shield, is known to corrode and fail. This can cause a wide range of bizarre electrical issues, including power steering failure.

Diagnosis Steps

1. Perform a full vehicle scan to identify all modules that are reporting communication loss. This helps determine if the issue is isolated to the PSCM or is a wider network problem.
2. Check the battery state of charge and perform a charging system test. Ensure battery voltage is above 12.6V with the engine off and stable around 14V when running. Inspect all battery cable connections for tightness and corrosion.
3. Inspect the main fuses for the Electric Power Steering (EPS) system. Check both the under-hood fuse block and any mega-fuses on the positive battery terminal.
4. Inspect the G218 ground. This is the most critical step. Remove the driver's side A-pillar trim and dash-end panel. Locate the ground stud (usually a 10mm nut) near the A-pillar/speaker area. Remove the nut and wire, check for trapped insulation, sand the contact surfaces to bare metal, and re-secure it tightly.
5. Inspect the wiring and connectors at the power steering rack itself for any visible damage, corrosion, or loose connections. Check for signs of water intrusion, especially on trucks used for launching boats.
6. Following TSB #PIT5457D, remove the driver and passenger door sill plates and inspect the wiring harnesses in the channels for chafing, moisture, or damage, paying close attention to the communication enable circuit (wire 5986).
7. For 2019+ models, inspect the main braided chassis ground strap located behind the right front wheel well liner for corrosion or breakage.
8. If all wiring, grounds, and power are confirmed good, a professional may need to perform CAN bus network resistance and voltage tests to isolate a fault. If the network is healthy, the PSCM/steering rack assembly is the likely cause.

Parts You'll Likely Need

• Electric Power Steering Rack and Pinion Assembly (OEM #86553003 (Example for 2015 w/ Enhanced Towing Pkg)) — This is required if the integrated Power Steering Control Module (PSCM) has failed internally and all external wiring/grounds are good. The part number is highly specific to VIN, year, and options.
  Trusted brands: ACDelco (GM Genuine), Cardone, Detroit Axle
  OEM price range: $1200-$2000
  Aftermarket price range: $700-$1300
• Wiring Repair Supplies — Needed to fix chafed or broken wires in the door sill harnesses or at the G218 ground. Includes sandpaper, dielectric grease, butt connectors, and electrical tape.
  OEM price range: $5-$25
  Aftermarket price range: $5-$25
• Battery — A failing battery with low or unstable voltage can be the root cause of the communication fault.
  Trusted brands: ACDelco, Optima, DieHard
  OEM price range: $200-$350
  Aftermarket price range: $150-$250

Related Codes That Often Appear With This One

• U0073 — Control Module Communication Bus 'A' Off. This is a general network code often set alongside specific module communication faults like U0131, especially when the G218 ground is at fault.
• U0121 — Lost Communication With Anti-Lock Brake System (ABS) Control Module. The ABS (EBCM) and PSCM are on the same high-speed CAN bus, and a network problem like a bad ground or chafed wire often affects both.
• U0140 — Lost Communication With Body Control Module (BCM). The BCM is a central hub for communication, and TSB #PIT5405C directly links the G218 ground issue to BCM communication faults.
• U0415 — Invalid Data Received From Anti-Lock Brake System (ABS) Control Module. This can occur when communication is unstable. On some GM vehicles, a software glitch can cause this code to remain 'current' even after the issue (like a dead battery) is fixed, requiring a dealer to update the PSCM software.

Technical Service Bulletins (TSBs) & Recalls

• Addresses a wide range of electrical issues including U0131, steering kickback, and blank displays, pointing to the G218 ground as a primary cause due to trapped insulation. Also mentions checking battery cables and starter connections.
• Covers loss of communication with various modules including the PSCM. It directs technicians to inspect for damaged wiring in the harness located under the driver and passenger door sill plates.
• A service update for certain 2020 models with the 2.7L engine concerning an engine wiring harness that may be improperly routed or wrapped, leading to chafing, shorting, and potential communication codes or stalling.

Platform-Specific Known Issues

• G218 Ground Defect: TSB #PIT5405C identifies a common factory flaw where the dash insulator is caught under the main body ground for the BCM, causing a host of communication issues including U0131. Numerous owner videos and forum posts confirm this is the first place to look.
• Sill Plate Harness Damage: TSB #PIT5457D warns that wiring under the door sill plates can be damaged, leading to communication loss with the PSCM and other modules. This can be caused by moisture getting trapped under the sill plates.
• Owner Experience (G218 Fix): A user on YouTube commented on a G218 fix video, "Man you solved the biggest headache ever! I have spent hours on google trying to figure out the ground issue. After watching your video and 30 minutes it totally fixed my truck! Thanks so much".
• Owner Experience (Battery): On a Reddit thread for a 2020 Sierra with identical symptoms, a user stated, "Had same issue at 700 miles turned out to be a bad cell in the battery."

Mechanic-Grade Diagnostic Values

• High-Speed CAN Bus Resistance — expected: Approximately 60 Ω (Ohms) when measured between Pin 6 and Pin 14 of the Data Link Connector (DLC) with the battery disconnected.. Failure: A reading of ~120 Ω indicates an open circuit or a missing termination resistor. A reading significantly less than 60 Ω suggests a short between the CAN lines.
• High-Speed CAN Bus Voltage (Key On, Engine Off) — expected: Both CAN High (Pin 6) and CAN Low (Pin 14) should rest at approximately 2.5V. During data transmission, CAN High should toggle to ~3.5V and CAN Low should toggle to ~1.5V.. Failure: Voltages that are stuck high, low, or at battery/ground potential indicate a shorted wire or a faulty module dragging down the bus.
• Battery Cable Torque Specs — expected: Positive and negative battery cable clamps: 7 Nm (62 lb in). Battery fuse block connections: 15 Nm (11 ft lb). Negative cable to engine block: 45 Nm (33 ft lb).. Failure: Loose connections can cause intermittent voltage drops, leading to communication faults.

Scan Tool Commands That Help

• GM GDS2 (Global Diagnostic System 2): Power Steering Control Module Programming — This function is required after replacing the power steering rack assembly. It uses the GM Service Programming System (SPS) to load the correct software and vehicle calibration into the new PSCM.
• GM GDS2 (Global Diagnostic System 2): Steering Angle Sensor Centering/Calibration — Required after PSCM programming, wheel alignment, or any service on steering components. This procedure zeroes the steering angle sensor, which is critical for the proper function of the PSCM and Stabilitrak/ESC systems.

Wiring & Ground Locations

• G218 — Under the driver's side of the dashboard, attached to the A-pillar support brace, often near the speaker.. This is a primary ground point for the Body Control Module (BCM) and other interior modules. A poor connection here, often due to trapped insulation, is a top cause of network-wide communication codes, including U0131.
• PSCM Connector (CAN Bus Wires) — At the power steering rack and pinion assembly.. These are the direct communication lines to the module. Pin 12 is often the Tan/Black wire (CAN High) and Pin 13 is the Tan wire (CAN Low) on the 14-pin connector. Verifying signal integrity here is a key diagnostic step.
• Main Chassis Ground Strap (T1XX Platform) — Behind the front passenger side wheel well liner, connecting the frame to the body/battery negative path.. On 2019+ models, this uninsulated braided strap is highly prone to corrosion in salt-belt regions. Its failure can cause a massive voltage drop for the entire vehicle's electrical system, often presenting as a power steering failure first due to the high current draw.

Real Owner Repair Stories

• gm-trucks.com forum user (2015 GMC Sierra) — Intermittent loss of power steering, service power steering message, multiple warning lights.
  ❌ Tried (didn't work) Initially suspected battery or alternator.
  ✅ What actually fixed it Located the G218 ground stud behind the driver's side A-pillar trim. The sound deadening mat was trapped under the ground terminal. After removing the 10mm nut, cutting back the mat, cleaning the contact surfaces, and retightening the nut, all symptoms were resolved.
• Reddit user in r/mechanicadvice (2016 Chevy Silverado) — U0131 code and loss of power steering returned shortly after the dealer performed the G218 ground fix.
  ❌ Tried (didn't work) Cleaning the G218 ground (only a temporary fix)., Replacing the battery.
  ✅ What actually fixed it The negative battery cable had developed high internal resistance. Replacing the entire negative battery cable assembly provided a permanent fix.
• Reddit user in r/Silverado (2020 GMC Sierra) — Sudden loss of power steering, ABS, traction control, and numerous trailer-related error messages. Multiple low-voltage codes stored.
  ❌ Tried (didn't work) Testing the battery (was good)., Testing the alternator (was good).
  ✅ What actually fixed it The main braided ground strap located behind the front passenger wheel well liner had corroded completely through. Replacing the strap with a new one resolved all electrical faults.

OEM Part Supersession History

• 23276192 → 84102273, then 84578298, then 85734721 — GM has released multiple revisions of the electric power steering rack assembly for this platform, likely to improve reliability and address internal component failures.
  Heads up: Always verify the correct part number for your specific VIN and RPO codes using a GM parts catalog, as there are variations based on cab, bed, and suspension options.

Model Year Variations Within This Range

• 2014-2018 (K2XX Platform): These models are most susceptible to the G218 ground fault under the driver's side dash due to the dash insulator mat being trapped during assembly.
• 2019-2020 (T1XX Platform): These models are more prone to failure of the main braided chassis-to-body ground strap located behind the front passenger wheel well. This strap corrodes from exposure to the elements (especially in salt-belt regions), causing widespread, severe electrical faults that often manifest as power steering failure.