U0415 on 2015-2020 Chevrolet Suburban: Causes for Invalid ABS Module Data

What's Unique About the 2015-2020 Chevrolet SUBURBAN

The 2015-2020 Suburban and its K2XX platform mates (Tahoe, Yukon, Silverado, Sierra, Escalade) are specifically prone to this code due to several well-documented issues. Manufacturer bulletins point directly to problems like low brake fluid causing erroneous signals during turns or braking, and to specific wiring harnesses under the door sill plates and behind the instrument panel that are susceptible to moisture, corrosion, or pinching. TSB PIT5457D specifically mentions that the Communication Enable circuit (5986) 🎬 Watch: How to perform a GM CAN-bus electrical diagnostic. is a common point of failure in these harnesses.

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).
• "Service StabiliTrak" message on the DIC.
• ABS warning light illuminated.
• StabiliTrak / Traction Control warning light illuminated.
• Check Engine Light illuminated.
• Inoperative systems like windshield wipers, audio, or a dead battery (in cases of severe wiring shorts).
• Loss of power steering assist (if communication with the PSCM is also lost).
• Sudden erratic speedometer behavior and loss of cruise control.

Most Likely Causes

1. Low Brake Fluid Level 🔴 High Probability According to GM TSB #PIT5490B, the brake fluid level sensor is very sensitive. During hard turns, acceleration, or braking, fluid can slosh in the reservoir, momentarily triggering a 'low fluid' signal to the EBCM. The EBCM then sends this data to the Chassis Control Module, which interprets it as invalid and sets U0415, often displaying a "Service Trailer Brake" message.
   How to confirm: Visually inspect the brake fluid level in the master cylinder reservoir. If it is near the 'MIN' mark, this is the likely cause. A scan tool can also monitor the 'Brake Fluid Level Sensor' status in the EBCM data list, which will display 'OK' or 'Low'.
   Typical fix: Top off the brake fluid to the 'MAX' line using the correct DOT 3 or DOT 4 fluid. It is critical to also inspect for the cause of the low fluid, such as worn brake pads or a leak in the brake system, including the rear of the master cylinder which can leak into the brake booster.
   Est. part cost: $5-$15 for a bottle of DOT 3 or DOT 4 brake fluid.
2. Damaged or Corroded Wiring Harness Under Sill Plates 🟡 Medium Probability GM TSB #PIT5457D specifically calls out this issue. The wiring harnesses that run along the floor under the driver and passenger door sill plates are susceptible to moisture intrusion from wet shoes, clogged sunroof drains, or body seam leaks. This leads to corrosion and open circuits in the CAN bus wiring, particularly the Communication Enable circuit (5986).
   How to confirm: Remove the driver and passenger front sill plates and peel back the carpet to visually inspect the large wiring harnesses and splice packs (like Splice J365 on the passenger side) for signs of water damage, green or white corrosion, or physically broken wires. A multimeter can be used to check for voltage on circuit 5986 at the EBCM connector.
   Typical fix: The damaged section of the wire must be cut out and repaired using solder and heat-shrink tubing or appropriate weatherproof connectors. The source of the water leak must be found and addressed to prevent a repeat failure.
   Est. part cost: $10-$30 for wiring repair supplies.
3. Pinched Wiring Harness in Instrument Panel ⚪ Low Probability GM TSB #PIT5288H identifies a potential for the instrument panel harness to be pinched between the left I/P dash mounting bracket and the body, near the parking brake pedal assembly. This can short communication wires and cause a host of electrical issues, including setting U0415. Another service bulletin, #15-08-45-001, also addresses a harness rubbing near the park brake bracket.
   How to confirm: Inspect the wiring harness on the left side of the instrument panel from underneath the dash, near the fuse block and bulkhead connectors, for any signs of being pinched, chafed, or damaged by the metal dash bracket. The harness may not move freely if it is caught.
   Typical fix: Loosen the I/P dash mounting bracket bolts to free the harness. Open the harness loom, repair any damaged wires, and re-route or secure the harness with a tie-strap to prevent it from being pinched again.
   Est. part cost: $10-$30 for wiring repair supplies.
4. Failing Electronic Brake Control Module (EBCM) ⚪ Low Probability While less common than wiring issues on this platform, the EBCM (ABS module) can fail internally, causing it to send out corrupted data or stop communicating altogether.
   How to confirm: This is typically a diagnosis of exclusion. If all wiring (including power, ground, and communication enable circuit 5986), connections, and fuses have been confirmed to be good, the module itself is the likely culprit. A high-end scan tool may be able to detect an internal module fault.
   Typical fix: Replace the Electronic Brake Control Module. The new module must be programmed to the vehicle's VIN using a specialized scan tool.
   Est. part cost: $200-$600 for a new or remanufactured EBCM.

Rare But Worth Checking

• Faulty Trailer Brake Control Switch:

Diagnosis Steps

1. Check the brake fluid level in the master cylinder. If low, top it off and inspect the brake system for leaks or worn pads. This is the simplest and a very common fix per TSB #PIT5490B.
2. Connect a professional OBD-II scanner capable of reading all vehicle modules. Check for any other DTCs, especially other U-codes, which can help pinpoint the location of a wiring fault.
3. Using the scan tool, monitor the 'Brake Fluid Level Sensor' parameter in the EBCM data list to see if it reads 'Low' intermittently.
4. Following TSB #PIT5457D, remove the driver and passenger front door sill plates and pull back the carpet. Carefully inspect the large wiring harnesses and splice connectors for any signs of corrosion (green/white powder), water intrusion, or physical damage.
5. Following TSB #PIT5288H, inspect the wiring harness on the left side of the instrument panel (from below) for any signs of being pinched or chafed against the metal dash support bracket near the parking brake.
6. Inspect the main electrical connector at the Electronic Brake Control Module (EBCM) for corrosion, bent pins, or a loose connection. Apply dielectric grease if moisture is suspected but no corrosion is present.
7. Using a multimeter, verify that the EBCM has proper power and ground. Specifically test the Communication Enable circuit (5986) for ~12 volts when the ignition is on, as detailed in TSB PIT5457D.

Parts You'll Likely Need

• Brake Fluid (DOT 3 or DOT 4) — The most common cause cited in a TSB is a low brake fluid level causing erroneous sensor readings during vehicle maneuvers.
  Trusted brands: ACDelco, Prestone, Bosch
  OEM price range: $8-$20
  Aftermarket price range: $5-$15
• Electronic Brake Control Module (EBCM) (OEM #84778360 (Replaces: 23154723, 23154727, 23223286, 84601113; Replaced by: 85698742)) — If all wiring issues are ruled out, the module itself may have failed internally, causing it to send invalid data. Part number may vary by specific options.
  Trusted brands: ACDelco (GM Genuine), Dorman
  OEM price range: $200-$450
  Aftermarket price range: $180-$350

Related Codes That Often Appear With This One

• U0077 — Often appears with U0415 in cases of wiring harness damage, as it indicates a general High Speed Communication Bus issue.
• U0121 — Indicates 'Lost Communication With Anti-Lock Brake System (ABS) Control Module'. This may appear alongside U0415 if the communication issue is intermittent, sometimes dropping out completely and other times just being invalid.
• U0126 — Indicates 'Lost Communication With Steering Angle Sensor Module'. This sensor's data is critical for the EBCM, and a shared wiring harness issue (per TSB PIT5288H) can cause both codes.
• U0401 — Indicates 'Invalid Data Received From ECM/PCM'. This can be set in conjunction with U0415 when a widespread network issue is present, often pointing to a harness problem.
• U0428 — Indicates 'Invalid Data Received From Steering Angle Sensor Module'. This points to a problem with the SAS data that the EBCM relies on, often caused by the same wiring faults that trigger U0415.

Technical Service Bulletins (TSBs) & Recalls

• PIT5490B: Describes U0415 being set due to a low brake fluid level, causing a "Service Trailer Brake" message.
• PIT5457D: Points to corroded/damaged wiring under the sill plates as a cause for U0415 and other communication codes.
• PIT5288H: Identifies a pinched instrument panel harness as a potential cause for U0415 among other electrical 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.
• TSB #PIT5457D: Loss of communication and various U-codes, including U0415, are linked to damaged or corroded wiring found under the driver and passenger sill plates. [TSB #PIT5457D]
• TSB #PIT5288H: A wide range of electrical problems and communication codes, including U0415, can be caused by a pinched wire harness near the left side of the instrument panel. [TSB #PIT5288H]

Mechanic-Grade Diagnostic Values

• Voltage on Communication Enable Circuit 5986 at the EBCM connector — expected: Approximately 12 Volts when the ignition is in ACC, ON, or START.. Failure: Low or no voltage indicates an open, short, or high resistance in the circuit, often under the sill plates.
• Load test of Communication Enable Circuit 5986 — expected: The circuit should illuminate a small 194 bulb and maintain at least 11 volts across the bulb.. Failure: If the bulb does not light or voltage drops below 11V, it confirms high resistance that a simple multimeter test might miss. The BCM will shut down this circuit if it draws more than 0.88 amps.
• Resistance of the Chassis High-Speed CAN Bus — expected: Approximately 60 Ohms when measured between Pin 12 (CAN High) and Pin 13 (CAN Low) at the Data Link Connector (DLC).. Failure: A reading of 120 Ohms indicates that one of the two terminating resistors (one of which is in the EBCM) is not being seen by the network, pointing to a break in the wiring. A reading near zero ohms indicates a short between the two CAN wires.

Scan Tool Commands That Help

• GM GDS2: EBCM Data List -> 'Brake Fluid Level Sensor' — Use this to confirm the 'low brake fluid' cause per TSB #PIT5490B. It allows you to see if the sensor is intermittently reporting 'Low' status, which triggers the U0415 code in the Chassis Control Module, even if the fluid level appears acceptable upon visual inspection.

Wiring & Ground Locations

• Circuit 5986 — This is the Communication Enable circuit. It runs from the Body Control Module (BCM) to several other modules, including the EBCM. Known problem areas are under the driver and passenger sill plates and where the harness can be pinched by the spare tire crossmember on short-wheelbase utilities.. This circuit provides a 'wake-up' signal to the EBCM. If the circuit has high resistance or is open, the EBCM may not communicate properly, leading to U-codes, including U0415.
• Splice J365 — Located in the wiring harness under the passenger front sill plate.. This is a known point of failure for Circuit 5986 due to water intrusion and corrosion. TSB #PIT5457D specifically calls out inspecting this splice pack when diagnosing communication issues.
• EBCM Ground — A primary ground for the EBCM is typically located on the frame rail below the driver's door.. A poor or corroded ground connection can cause a variety of intermittent electrical and communication faults for the ABS system, leading to codes like U0415.
• DLC Pins 12 & 13 — The Data Link Connector (OBD-II port) under the driver's side dashboard.. On this platform, the Chassis High-Speed CAN network, which the EBCM communicates on, uses Pin 12 (CAN High) and Pin 13 (CAN Low). These pins are used to test the resistance of the entire network.

Real Owner Repair Stories

• Ford Edge Forum user 'CrackedDSM' (Ford Edge (Note: While not a Suburban, the diagnostic principle for finding a hidden wiring break is identical for U0415)) — ABS, traction control, stability control lights on. Code U0415 present after a wheel speed sensor was replaced.
  ❌ Tried (didn't work) Replacing the right rear ABS sensor., Visual inspection of the harness (initial inspection found nothing).
  ✅ What actually fixed it A break in the ABS wiring harness was found hidden under the back seat, inside the car. The wire was broken in a way that was not visible until the harness was physically moved. Repairing the broken wire resolved all issues and codes. The user recommends performing a continuity check on the harness from the sensor to the module.

OEM Part Supersession History

• 23337305 → 85073617 — GM regularly updates service part designs to integrate new materials and technologies.
  Heads up: Part 85073617 is the current GM Genuine Parts replacement for the Trailer Brake Control Module for the 2015-2020 Suburban with option code JL1 (Integrated Trailer Brake Control).