U0415 on 2014-2019 Chevy Silverado 1500: ABS Communication Fault Causes & Fixes

What's Unique About the 2014-2019 Chevrolet SILVERADO 1500

On the K2XX generation of Silverado (2014-2019 LD) and its platform mates, this code is frequently not caused by a failed ABS module itself. Instead, GM has issued multiple Technical Service Bulletins (TSBs) pointing to specific, common issues. These include the brake fluid level being low, which can cause the fluid to slosh and trigger the sensor during turns or braking (TSB #PIT5490B), and known wiring harness problems in the sill plates (TSB #PIT5457D) and instrument panel (TSB #PIT5288H). A software calibration error in the Power Steering Control Module (PSCM) can also cause U0415 to remain as a current code after the initial fault (like a dead battery) is fixed, requiring a dealer software update as per TSB PIT5593A/20-NA-113.

Diagnostic Flowchart

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

Generation note: This year range covers the third generation (K2XX; 2014-2018 and 2019 'LD' models) and the first year of the fourth generation (T1XX; 2019). The cited TSBs and most common issues primarily reference the K2XX platform, where these problems are well-documented.

Symptoms You May Notice

• "Service Trailer Brake System" message in the Driver Information Center (DIC).
• "Service Stabilitrak" message.
• "Steering Assist is Reduced Drive with Care" message.
• ABS warning light illuminated.
• Traction control warning light illuminated.
• Intermittent loss of power steering assist.
• Cruise control may be inoperative
• In rare cases, dead battery or inoperative wipers if related to a major wiring short. [TSB #PIT5288H]

Most Likely Causes

1. Low Brake Fluid Level 🔴 High Probability As per TSB #PIT5490B, fluid sloshing in a near-empty reservoir during turns or hard braking can momentarily trip the level sensor. The EBCM sends this 'low fluid' data, which the Chassis Control Module sees as an invalid state, triggering U0415 and a 'Service Trailer Brake' message.
   How to confirm: Visually inspect the brake fluid level in the master cylinder reservoir. Use a scan tool (GDS2) to monitor the 'Brake Fluid Level Sensor' parameter within the EBCM data list; it will switch from 'OK' to 'Low'.
   Typical fix: Fill the master cylinder with the correct DOT 3 or DOT 4 brake fluid to the 'MAX' line. Crucially, investigate the reason for the low fluid, such as worn brake pads or a leak in the system, including the rear of the master cylinder.
   Est. part cost: $5-$15
2. Damaged or Corroded Wiring Harness 🔴 High Probability TSB #PIT5457D specifically calls out wire harnesses in the driver and passenger sill plates being susceptible to water intrusion, leading to corrosion and high resistance. TSB #PIT5288H points to a harness being pinched by a metal bracket behind the left instrument panel side cover. These wiring faults disrupt communication on critical data lines.
   How to confirm: Remove the sill plates and/or instrument panel side cover to visually inspect the wiring harnesses for chafing, corrosion (green crust), breaks, or pinched wires. Per TSB #PIT5457D, a multimeter can be used to check for low voltage on the Communication Enable circuit (Circuit 5986).
   Typical fix: Repair the damaged section of the wire harness. This involves cutting out the bad section, splicing in new wire (of the same gauge), and protecting the repair with heat shrink tubing to prevent future moisture damage. Reroute the harness if it was pinched.
   Est. part cost: $10-$50
3. Weak or Failing Battery 🟡 Medium Probability Modern trucks are highly sensitive to voltage. A weak or dying battery can cause low voltage during startup, leading to a cascade of communication errors between modules. The Power Steering Control Module is particularly sensitive and may set a U0415 that won't clear, even after the battery is replaced, until a software update is performed.
   How to confirm: Test the battery with a proper load tester. A simple voltage check is often insufficient. Many auto parts stores offer this service for free. Check for other communication codes ('U' codes) stored in various modules.
   Typical fix: Replace the battery. If codes persist, especially the 'Steering Assist is Reduced' message, the PSCM may need to be reprogrammed by a dealer or a shop with GM software access, as described in TSB PIT5593A/20-NA-113. 🎬 Watch: How to fix the Steering Assist is Reduced warning.
   Est. part cost: $150-$300
4. Poor Connection at a Control Module 🟡 Medium Probability Vibrations and moisture can lead to poor connections over time. TSB #PIT5405C suggests checking connections at the Body Control Module (BCM) when multiple communication codes, including U0415, are present.
   How to confirm: Disconnect, inspect, and reconnect the main electrical connectors at the EBCM (ABS module, located on the driver's side frame rail) and the BCM (Body Control Module, typically located inside the cabin, up under the driver's side dash). Look for bent or corroded pins and signs of water intrusion.
   Typical fix: Clean the connector pins with an electrical contact cleaner. Apply dielectric grease to the connector seal before reconnecting to prevent future moisture intrusion.
   Est. part cost: $5-$10

Rare But Worth Checking

• Failed Electronic Brake Control Module (EBCM): While possible, this is far less common than wiring, fluid level, or battery issues. The module itself can fail internally, but it should only be replaced after all other potential causes have been ruled out through thorough diagnosis.
• Failed Wheel Speed Sensor / Hub Assembly: A faulty wheel speed sensor can send erratic or no data to the EBCM. The EBCM then broadcasts this nonsensical data on the network, causing other modules to flag it as invalid and set U0415. This is often accompanied by a specific wheel speed sensor code (e.g., C0035) and a rumbling noise if the bearing in the hub is failing.
• Failed Body Control Module (BCM): A failing BCM can cause a wide range of bizarre electrical issues and set numerous communication codes across the vehicle. If U0415 is present with many other unrelated codes that persist after checking harnesses, the BCM could be the source. [NHTSA ODI #11518731]

Diagnosis Steps

1. Check Brake Fluid: Visually inspect the brake fluid level in the master cylinder. If it is low, top it off to the 'MAX' line with the manufacturer-specified fluid. Clear the codes and test drive, including some sharp turns and stops, to see if the code returns.
2. Scan for All Codes: Use a professional scan tool (not a basic engine code reader) to check for codes in all vehicle modules (EBCM, BCM, PSCM, etc.). The presence of many other communication 'U' codes points strongly towards a network or wiring issue.
3. Test the Battery: Have the battery professionally load-tested. A weak battery is a known cause of spurious communication faults on these trucks.
4. Inspect Sill Plate Wiring: Remove the driver's side sill plate to access the main wire harness. Carefully unwrap and inspect for any signs of chafing, corrosion from water entry (green crust), or broken wires, as detailed in TSB #PIT5457D. Pay close attention to the Communication Enable circuit (Circuit 5986).
5. Inspect Instrument Panel Wiring: Remove the driver's side instrument panel outer trim cover and inspect the wire harness in that area for any signs of being pinched or damaged by the metal dash bracket, as noted in TSB #PIT5288H.
6. Check Module Connectors: Inspect the large electrical connectors at the EBCM (ABS module, located on the driver's side frame rail) and the BCM (Body Control Module, located inside the cabin). Look for corrosion, moisture, or backed-out pins.
7. Network Diagnostics: If no physical damage is found, advanced diagnostics may be needed. This involves using a multimeter to check for power, ground, and network resistance at the EBCM connector. An oscilloscope may be needed to verify the CAN bus signal integrity.
8. Isolate the Module: If all wiring, battery, and connections are confirmed to be good, the EBCM itself may be faulty. This should be the final step in diagnosis.

Parts You'll Likely Need

• DOT 3 or DOT 4 Brake Fluid — This is required to top off a low master cylinder, which is a common cause of this code according to GM TSB #PIT5490B.
  Trusted brands: ACDelco, Prestone, Bosch
  OEM price range: $10-$20
  Aftermarket price range: $5-$15
• Electronic Brake Control Module (EBCM) (OEM #84778358) — If all wiring and fluid checks pass, the module itself may have failed. This part number is for early K2XX models (approx. 2014-2016) and has been superseded by newer numbers like 85698740. Always verify with VIN.
  Trusted brands: ACDelco (GM Genuine)
  OEM price range: $450-$650
  Aftermarket price range: $250-$450 (Remanufactured)
• Automotive Wire and Splice Connectors — Required for repairing damaged sections of the sill plate or instrument panel harnesses, which is a high-probability cause.
  Trusted brands: 3M, Dorman
  OEM price range: N/A
  Aftermarket price range: $10-$30

Related Codes That Often Appear With This One

• U0121 — Lost Communication With Anti-Lock Brake System (ABS) Control Module. This often appears with U0415 as they both relate to ABS communication failures.
• U0077, U0126, U0131, U0401, U0428 — These are all communication codes. When a wiring harness issue occurs (like in the sill plate), it can disrupt the entire network, causing communication loss with multiple modules simultaneously, as noted in TSB #PIT5457D.
• C0544, C0710 — These are chassis codes often related to steering and other systems that rely on on data from the ABS module. They can be set as a consequence of the invalid data from the U0415 fault, as seen in TSBs #PIT5405C and #PIT5288H.
• C0035, C0040 — These are wheel speed sensor codes. A faulty sensor can be the root cause, sending bad data to the EBCM, which then triggers the U0415. TSB PIT5593A notes that these codes can cause a persistent U0415 in the PSCM due to a calibration bug.

Technical Service Bulletins (TSBs) & Recalls

• Addresses a "Service Trailer Brake" message with DTC U0415. States the cause is often the brake fluid level being near minimum, allowing fluid to slosh during maneuvers and momentarily trip the level sensor. The fix is to top off the fluid and inspect for leaks or worn pads.
• Covers multiple communication codes, including U0415, caused by damaged or corroded wiring in the driver and passenger sill plates. It specifically mentions checking the Communication Enable circuit 5986 for opens or high resistance.
• Points to a wide array of electrical issues (including U0415) caused by a pinched wire harness behind the left side of the instrument panel, near the I/P mounting bracket. The fix is to free the harness and repair any damaged wires.
• Suggests checking connections at the Body Control Module (BCM) when a multitude of communication and chassis codes, including U0415, are present simultaneously. [NHTSA ID 10134293]
• Notes a calibration error in the Power Steering Control Module (PSCM) that can cause DTCs like U0415 to remain current even after the fault is gone (e.g., after a wheel speed sensor is fixed). This can cause a persistent "Steering Assist is Reduced" message until the PSCM is reprogrammed.

Platform-Specific Known Issues

• A 'Service Trailer Brake' message accompanied by DTC U0415 is frequently caused by a low brake fluid level, which sloshes during vehicle movement and momentarily trips the sensor, as documented in TSB PIT5490B.
• Water intrusion into the driver's side floor sill can corrode the main wiring harness that runs through it, causing high resistance on data lines and triggering U0415 along with a host of other communication codes. This is documented in TSB PIT5457D.
• A pinched wiring harness located behind the driver's side dash end cap is a known factory issue that can short communication wires, leading to U0415 and other bizarre electrical problems. This is documented in TSB PIT5288H.

Mechanic-Grade Diagnostic Values

• High-Speed CAN Bus Network Resistance — expected: Approximately 60 Ohms between Pin 6 (CAN-H) and Pin 14 (CAN-L) at the DLC with the battery disconnected.. Failure: A reading of 120 Ohms indicates one of the two terminating resistors (often in the EBCM or another module) is not being seen by the network, pointing to an open circuit. A reading significantly lower than 60 Ohms can indicate a short between the CAN lines.
• Communication Enable Circuit 5986 Voltage — expected: Approximately 12 volts (battery voltage) with the key in ACC, ON, or START.. Failure: Low or no voltage on this circuit at the EBCM connector prevents the module from 'waking up' to communicate on the network, directly causing communication codes like U0415.
• CAN Bus Voltage (Key On, Engine Off) — expected: CAN High (Pin 6) should be around 2.7V. CAN Low (Pin 14) should be around 2.2V.. Failure: Voltages that are stuck high, low, or at 0V indicate a short to power or ground on the network wiring.

Hidden / Shadow Codes Worth Checking

• U0415 with Symptom Byte 00: This specific variation is noted in GM preliminary information (PIC5923A) for setting in the Electronic Power Steering Control Module (EPSCM). It points towards a known software/calibration issue. (see via A professional scan tool like the GM GDS2 is required to view symptom bytes associated with a DTC.)

Scan Tool Commands That Help

• GDS2 (GM Global Diagnostic System 2): PSCM Programming — Use this function to update the Power Steering Control Module (PSCM) software. Per TSB 20-NA-113 (superseding PIT5593A), a calibration error can cause U0415 to remain as a 'current' DTC after a temporary fault (like a weak battery), even when the problem is resolved. Reprogramming the PSCM with the latest software corrects this bug.
• GDS2 (GM Global Diagnostic System 2): EBCM Data Display > Brake Fluid Level Sensor — To confirm the diagnosis from TSB #PIT5490B. This allows you to see the live status ('OK' or 'Low') of the brake fluid level sensor as seen by the EBCM, which can help identify intermittent faults caused by fluid sloshing.
• GDS2 (GM Global Diagnostic System 2): Electronic Brake Control Module Setup — This procedure is required after replacing the EBCM. It configures the new module to the vehicle's specific options and performs necessary calibrations.

Wiring & Ground Locations

• G218 — Under the driver's side of the dashboard, typically behind the A-pillar trim or kick panel, near the speaker.. This is a major interior ground point for multiple modules, including the BCM and instrument panel cluster. A poor connection here due to a loose nut or trapped insulation is a widely documented cause of random communication codes and bizarre electrical issues, including those that can lead to a U0415.
• EBCM Ground — On the frame rail directly under the driver's door area, near the EBCM/ABS pump assembly.. This is the primary ground for the Electronic Brake Control Module itself. Corrosion or a loose connection at this point can cause the EBCM to malfunction or send invalid data, directly triggering U0415.
• BCM (Body Control Module) — Inside the cabin, under the driver's side of the dashboard, to the left of the steering column and often integrated with the interior fuse block.. The BCM is a central communication hub. TSBs point to checking its connectors for issues. It also provides the 'wake-up' signal on Circuit 5986, which is essential for the EBCM to communicate.
• Circuit 5986 (Communication Enable) — Runs from the BCM to multiple modules, including the EBCM. Known chafe/corrosion points are in the harness under the driver's and passenger's sill plates.. This circuit provides a 12V signal from the BCM to 'wake up' other modules like the EBCM. An open or short in this wire prevents the EBCM from communicating, leading to a host of 'U' codes, including U0415.

Real Owner Repair Stories

• Reddit user in r/Silverado (2014-2018 Silverado (K2XX generation)) — Intermittent "Service Stabilitrak" message flashing on the dash.
  ❌ Tried (didn't work) Initial diagnosis was inconclusive as the message would come and go.
  ✅ What actually fixed it The issue was traced to the G218 ground. The user reported that foam insulation often gets caught under the ground nut, preventing a solid connection. Pulling the insulation away and tightening the ground nut resolved the problem permanently.
• YouTube video by 'Oil Light Reset' (Newer GMC Sierra / Chevrolet Silverado) — "Steering Assist is Reduced Drive with Care" message with code U0415 present in the Power Steering Control Module (PSCM).
  ❌ Tried (didn't work) Clearing the code with a basic scanner; the code would immediately return as 'current'.
  ✅ What actually fixed it The root cause was a dead/replaced battery which set the initial communication fault. However, due to a software bug in the PSCM, the code would not move to 'history' status. The final fix required taking the truck to a dealer to have the PSCM software updated per a known TSB.