U0415 on 2014-2019 GMC Sierra 1500: Causes for Invalid ABS Data

What's Unique About the 2014-2019 Gmc SIERRA 1500

For this generation of GMC Sierra and its K2XX platform mates, there are several well-documented, specific issues that lead to code U0415. Multiple Technical Service Bulletins (TSBs) point to non-module failures. The most common culprits are either a low brake fluid level causing the sensor to send erratic signals during vehicle motion, or specific wiring harnesses being pinched or corroded in the driver/passenger sill plates and behind the instrument panel. [PIT5490B, PIT5457D, PIT5288H] Owners frequently confirm these wiring and fluid issues in online forums.

Diagnostic Flowchart

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

Symptoms You May Notice

• "Service Trailer Brake" message on the Driver Information Center (DIC). [PIT5490B]
• "Service StabiliTrak" message on the DIC.
• ABS warning light illuminated.
• StabiliTrak or traction control warning light illuminated.
• Check Engine Light may be on.
• In some cases, seemingly unrelated electrical issues like inoperative wipers may occur if the cause is a widespread wiring problem. [PIT5288H]
• "Steering Assist is Reduced Drive With Care" message may appear in cases with broader network issues.

Most Likely Causes

1. Low Brake Fluid Level 🔴 High Probability → Shop Brake Fluid According to TSB #PIT5490B, fluid sloshing in a near-empty reservoir during turns, braking, or acceleration can cause the level sensor to send intermittent 'low' signals. The EBCM interprets this as invalid data, triggering U0415 and often a 'Service Trailer Brake' message.
   How to confirm: Visually inspect the brake fluid level in the master cylinder reservoir. Using a scan tool, monitor the 'Brake Fluid Level Sensor' parameter within the EBCM data list to see if it reads 'Low' or 'OK'.
   Typical fix: Top off the master cylinder with the correct DOT-rated brake fluid. It is critical to then inspect the entire brake system for leaks or worn pads to determine why the fluid was low in the first place.
   Est. part cost: $5-$15
2. Damaged or Corroded Wiring Harness 🔴 High Probability TSB #PIT5457D identifies wire harnesses under the driver and passenger sill plates as being susceptible to damage and corrosion from water intrusion. TSB #PIT5288H points to a pinched harness behind the left side of the instrument panel. 🎬 Watch: How to find and fix common Silverado electrical issues. Owners report finding green, corroded wires in these channels, specifically affecting the CAN bus or communication enable circuits.
   How to confirm: Remove the plastic sill plates and peel back the carpet to inspect the wiring channels for signs of water intrusion, corrosion (often a green crust on copper wires), or chafed/broken wires. Inspect the harness behind the driver's side dash panel for pinching or damage.
   Typical fix: Repair the affected wires by splicing in new sections with heat-shrink, sealed connectors. Clean any corrosion from connectors and ensure the harness is properly routed and protected from future moisture damage.
   Est. part cost: $10-$50
3. Faulty Electronic Brake Control Module (EBCM) 🟡 Medium Probability → Shop ABS Control Module
   How to confirm: After definitively ruling out all wiring, power, ground, and software issues, the module itself is the likely culprit. This requires a professional-grade scan tool to attempt communication and run internal self-tests.
   Typical fix: Replace the EBCM. The new module must be programmed to the vehicle's VIN and specific configuration using dealer-level software.
   Est. part cost: $250-$700
4. ABS Module Software/Programming Issue ⚪ Low Probability → Shop ABS Control Module A low voltage event (e.g., dead battery) can sometimes cause modules to lose synchronization or fail to clear a historical fault, making it appear current. A software update may be required to fix this logic.
   How to confirm: A dealer or qualified shop can check the current software calibration of the EBCM against the latest version available from GM. An owner complaint noted that reprogramming was performed as a potential fix. [ODI #11286489]
   Typical fix: Update or re-flash the EBCM with the latest manufacturer software.
   Est. part cost: $0-$200

Rare But Worth Checking

• Poor EBCM Ground Connection (G305):

Diagnosis Steps

1. Check the brake fluid level in the master cylinder. Top off if low and inspect for the cause (leaks, worn pads). Clear codes and re-test. This is the fix for TSB #PIT5490B.
2. Use a professional scan tool to read codes from ALL modules (EBCM, BCM, CCM, etc.), not just the engine computer.
3. If TSB #PIT5490B applies (Service Trailer Brake message), this strongly points to the brake fluid level as the cause.
4. Inspect the wiring harness under the driver and passenger sill plates for corrosion (green crust), damage, or moisture, as described in TSB #PIT5457D.
5. Inspect the wire harness to the left of the instrument panel for pinching, as described in TSB #PIT5288H.
6. Locate, disassemble, and clean the EBCM ground connection (G305) on the frame rail. Ensure it is tight and free of corrosion.
7. Verify the EBCM has clean, tight connections and proper power and ground using a multimeter, following diagnostic procedures in TSB #PIT5457D.
8. Check for available software updates for the EBCM and other related modules, especially if the issue occurred after a battery replacement.
9. If all other steps fail to find a fault, suspect a failed EBCM.

Parts You'll Likely Need

• Brake Fluid (OEM #ACDelco 19353461 (DOT 3)) — A low fluid level is a primary and well-documented cause for this code on this truck, as per TSB #PIT5490B.
  Trusted brands: ACDelco, Prestone
  OEM price range: $10-$20
  Aftermarket price range: $5-$15
• Electronic Brake Control Module (EBCM) (OEM #ACDelco 23380704 (Example only, VIN specific)) — If wiring, grounds, and fluid levels are confirmed to be good, the module itself may have an internal fault causing it to send invalid data. Part number is highly specific to VIN and options; the correct one must be verified.
  Trusted brands: ACDelco (GM Genuine)
  OEM price range: $400-$700
  Aftermarket price range: $250-$500

Related Codes That Often Appear With This One

• U0077 — Indicates loss of communication with the Chassis Control Module, often set alongside U0415 due to shared wiring harness issues as described in TSB PIT5457D. [1, PIT5457D]
• U0121 — Indicates lost communication with the ABS module (EBCM). This is more severe than U0415 and suggests a complete communication breakdown, often from the same wiring faults or a bad ground. [1, PIT5457D]
• U0126 — Indicates lost communication with the Steering Angle Sensor Module, which can be affected by the same network wiring problems. [1, PIT5457D, PIT5405C]
• C0544, C0710 — These are steering-related codes that can appear with U0415 when a general BCM or network wiring fault is present, as noted in TSBs PIT5288H and PIT5405C.

Technical Service Bulletins (TSBs) & Recalls

• PIT5490B: Diagnostic Tip - Service Trailer Brake Message With DTC U0415.
• PIT5457D: Loss of communication with EBCM, SWPS, PSCM, and/or SCM.
• PIT5288H: Intermittent Electrical Concerns, Wiper Inoperative, And Or A Dead Battery.
• PIT5405C: Intermittent No Crank/No Start, Multiple DTCs, And/Or Various Electrical Concerns.
🎬 See this walkthrough for diagnosing no-start and communication faults.

Platform-Specific Known Issues

• TSB #PIT5490B: A "Service Trailer Brake" message accompanied by U0415 is frequently caused by the brake fluid level being near the minimum mark. Topping off the fluid is the specified fix.
🎬 Watch: A quick guide to fixing the Service Trailer Brake message.
• TSB #PIT5457D: Communication codes, including U0415, can be caused by an open, damaged, or corroded wire in the Communication Enable circuit (5986) located under the driver and passenger sill plates.
• TSB #PIT5288H: A variety of electrical codes, including U0415, can be triggered by a pinched wire harness at the left instrument panel, near the fuse block.
• TSB #PIT5405C: A large group of communication DTCs, U0415 among them, can be traced back to issues with the body control module (BCM) and its associated wiring.

Mechanic-Grade Diagnostic Values

• High-Speed GMLAN Bus Resistance — expected: 60 Ohms (± 5 Ohms). Failure: A reading of ~120 Ohms indicates an open in the circuit or that one of the terminating resistors is offline. A reading significantly lower than 60 Ohms indicates a short between the CAN High and CAN Low wires.
• Communication Enable Circuit (Circuit 5986) Voltage — expected: Approximately 12 Volts (battery voltage). Failure: Low or no voltage when the BCM is awake (e.g., ignition ON) indicates an open, short, or high resistance in the circuit. This circuit is low amperage; it should light a small 194 bulb but not a standard test light.
• EBCM Power and Ground Pins — expected: Bright illumination of a test lamp on power pins; solid ground connection.. Failure: Dim or no light on power pins (1 and 25) indicates a power supply issue. High resistance on ground pins (13 and 38) indicates a bad ground.

Hidden / Shadow Codes Worth Checking

• U0415 set in Chassis Control Module (CCM): → Shop Body Control Module This is not a hidden code, but a crucial diagnostic detail. TSB #PIT5490B specifies that when the brake fluid level is low, the EBCM sends this data over the CAN bus, and it is the Chassis Control Module that receives it, flags it as invalid, and sets the U0415 code, which in turn triggers the 'Service Trailer Brake' message. (see via A professional scan tool that can read codes from all vehicle modules, including the CCM, not just the ECM.)

Scan Tool Commands That Help

• GDS2 (or equivalent professional scan tool): Monitor 'Brake Fluid Level Sensor' Parameter — When diagnosing U0415, especially if accompanied by a 'Service Trailer Brake' message. This allows you to see in real-time if the EBCM is reporting the fluid level as 'OK' or 'Low', which is the direct cause outlined in TSB #PIT5490B.
• GDS2 (or equivalent professional scan tool): Clear Faults in All Modules — After a battery replacement or low voltage event. Communication codes like U0415 can get 'stuck' in modules like the Power Steering Control Module (PSCM) as a current fault. A powerful scan tool may be required to successfully clear them from all modules. If they persist, a dealer software update for the affected module may be necessary.

Wiring & Ground Locations

• Communication Enable Circuit 5986 — Known problem areas are in the wiring harness channel located under the driver's and passenger's plastic sill plates.. This circuit provides a 'wake-up' signal from the BCM to modules like the EBCM. If it has high resistance or is open/shorted due to corrosion or damage in the sill plate area, the EBCM cannot communicate properly, leading to a host of U-codes, including U0415.
• Splice J365 — Located within the wiring harness under the passenger's front sill plate.. This is a known splice point for Circuit 5986. Corrosion or a poor connection at this splice can cause an open or high resistance, disrupting communication with the EBCM.
• Main Battery Ground Cable — The negative battery cable has two main ground points: one on the engine block (typically 13mm bolt) and one on the vehicle frame near a body mount (typically 10mm bolt).. A poor main ground connection can cause low voltage and electrical noise throughout the vehicle, leading to intermittent communication faults and multiple U-codes.
• G103 — Located on the cowl at the left rear of the engine compartment, often above the brake booster.. This is a major ground point for many critical interior and communication modules, including the BCM, Instrument Panel Cluster (IPC), and the Data Link Connector (DLC) itself. A fault here can cause widespread communication chaos.

Real Owner Repair Stories

• Falcon's Garage on YouTube and owner comments (2014-2019 GMC Sierra / Chevy Silverado) — "Steering Assist is Reduced Drive With Care" message, multiple communication codes including U0415, Service Stabilitrak warnings.
  ❌ Tried (didn't work) Initial assumption of a major steering or brake system failure.
  ✅ What actually fixed it The vehicle's battery had died or was weak. After replacing the battery and fully disconnecting it to clear the module memory, all error codes and symptoms disappeared. The key takeaway is that a low voltage event can cause communication codes to get 'stuck' in a current state, and a simple battery replacement is often the fix.

"I Checked Everything" — The Actual Cause

• A common scenario for this code is that all wiring tests for continuity and resistance check out perfectly, grounds are clean, and the EBCM communicates with a scan tool. The actual cause is a software glitch in a related module, like the Power Steering Control Module (PSCM), which fails to move a historical U0415 code (set during a previous battery drain) to 'history' status. The fault appears current and active, but no physical problem exists. The fix is either clearing the code with a high-end scan tool or having a dealer re-flash the module that refuses to clear the code.

OEM Part Supersession History

• 23355956, 84074944 → 84256785 — Part has been updated or revised by the manufacturer.
  Heads up: This part requires programming and/or special setup procedures using GM Service Information to ensure proper operation in the vehicle. It is not a plug-and-play replacement.

Model Year Variations Within This Range

• 2014-2019: While the causes for U0415 are consistent across this generation, it's important to use the correct diagnostic procedure for the CAN bus. For these K2XX platform trucks, measuring resistance between pins 6 and 14 of the DLC should yield 60 ohms. On some later model GM trucks (approx. 2020+), the network architecture changed, and a reading of 120 ohms at the DLC is normal. Using the wrong specification could lead to misdiagnosis.