C0055 on 2015-2019 Chevrolet Colorado: Rear Wheel Speed Sensor Circuit Fault Guide

What's Unique About the 2015-2019 Chevrolet COLORADO

While any vehicle can have a sensor fail, the 2015-2019 Colorado and its sibling, the GMC Canyon, are subject to a specific issue documented by GM. A Technical Service Bulletin (TSB PIT5499B) points to water intrusion and corrosion at the main Electronic Brake Control Module (EBCM) electrical connector as a potential cause for C0055 and other related ABS faults. This makes inspecting the EBCM connector a critical and unique first step for this particular truck, as the problem is often at the module connector, not the sensor itself.

Diagnostic Flowchart

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

Symptoms You May Notice

• ABS warning light illuminated
• StabiliTrak or Traction Control (TC) warning light illuminated
• "Service Trailer Brake" message on the Driver Information Center (DIC)
• ABS system is non-functional (wheels may lock during hard braking)
• "Service Stabilitrak" message on DIC
• Brake pedal feels different, either spongy or hard
• Instrument cluster may temporarily show all zeros or become unresponsive in severe electrical fault cases.

Most Likely Causes

1. Water Intrusion / Corrosion at EBCM Connector 🔴 High Probability As documented in GM Technical Service Bulletin #PIT5499B, the EBCM connector on these trucks can be susceptible to water intrusion, leading to corrosion on the connector pins. The module's location on the frame rail makes it vulnerable to road spray.
   How to confirm: Disconnect the main electrical connector at the Electronic Brake Control Module (located on the ABS hydraulic unit in the engine bay) and carefully inspect the pins and connector housing for any signs of moisture, green or white corrosion, or bent pins.
   Typical fix: Clean the connector and module pins meticulously with an electrical contact cleaner and a small, soft brush. If corrosion is severe, the connector pigtail and/or the EBCM may need to be replaced. Apply dielectric grease to the connector seal upon reassembly to prevent future water intrusion. If corrosion is found, TSB PIT5499B recommends replacing the affected terminals and the EBCM.
   Est. part cost: $5-$20 for cleaner and grease; $50-$150 for a new pigtail if needed. EBCM replacement is significantly more expensive.
2. Faulty Rear Wheel Speed Sensor 🟡 Medium Probability Wheel speed sensors are exposed to harsh conditions (water, dirt, debris) under the vehicle, which can lead to failure over time. The wiring harness is also susceptible to damage from off-roading or road debris.
   How to confirm: Use a scan tool to monitor live data from both rear wheel speed sensors while driving. The faulty sensor will likely show an erratic or zero MPH reading compared to the others. You can also disconnect the sensor and test its internal resistance with a multimeter (compare to the known-good sensor on the other side). An open loop (OL) reading indicates a bad sensor.
   Typical fix: Replace the faulty rear wheel speed sensor. They are typically held in by a single T30 Torx bolt on the wheel hub/bearing assembly.
   Est. part cost: $25-$75
3. Damaged Wheel Speed Sensor Wiring or Connector 🟡 Medium Probability The wiring harness running to the wheel hub is susceptible to damage from road debris, improper suspension work, or chafing against chassis or suspension components. The plastic clips holding the harness can also break, allowing the wire to contact moving parts.
   How to confirm: Visually inspect the entire length of the wiring harness from the back of the wheel hub up into the main vehicle harness. Look for breaks, chafing, melted sections, or corrosion in the sensor's plug. One owner found the wire frayed after off-roading, which caused the warning lights.
   Typical fix: Repair the damaged section of wire or replace the sensor pigtail/harness. Pigtail kits with color-coded wires are available for this repair.
   Est. part cost: $10-$50 for repair materials or a pigtail.

Rare But Worth Checking

• Faulty Electronic Brake Control Module (EBCM): This is rare and should only be considered after all other possibilities (wiring, sensors, and especially the EBCM connector inspection) have been exhausted. The TSB points to the connector being the issue far more often than the module itself. However, if severe corrosion from water intrusion has damaged the module's pins, replacement may be necessary.
• Damaged Tone Ring: The tone ring, which the sensor reads, is integrated into the rear wheel hub/bearing assembly. Damage is uncommon but can happen if the bearing fails or during incorrect service. This usually presents with other noises or symptoms of a bad wheel bearing. Metallic debris can also stick to the magnetic ring and disrupt the signal.

Diagnosis Steps

1. Read all codes from the EBCM using a capable OBD-II scanner. Note any other wheel speed or communication codes.
2. CRITICAL: Disconnect the battery. Locate the EBCM on the ABS hydraulic unit in the engine bay. Disconnect its large electrical connector and thoroughly inspect both the harness side and the module side for any signs of water, blue/green corrosion, or bent pins. This is the issue cited in TSB #PIT5499B.
3. If corrosion is found, clean it with electrical contact cleaner and a small brush. Let it dry completely and apply dielectric grease to the seal before reconnecting. Clear codes and re-test. If corrosion is severe or has damaged pins, the connector pigtail or the entire EBCM may need replacement.
4. If the connector is clean, proceed to inspect the rear wheel speed sensors. Raise the rear of the vehicle and secure it on jack stands.
5. Visually inspect the wiring harness for both rear wheel speed sensors from the wheel hub up to where it joins the main harness. Look for any signs of physical damage, chafing, or broken retaining clips.
6. If no visible damage is found, use a scan tool that can read live ABS data. Monitor the rear wheel speed signals while spinning the wheels by hand or while driving. A faulty sensor will read 0 MPH or have an erratic signal compared to the others.
7. Once the faulty sensor is identified, replace it. The sensor is typically held by a single T30 Torx bolt.
🎬 Watch: Step-by-step guide to replacing the rear wheel speed sensor.
8. If sensors and wiring appear good, the final step would be to test the circuit continuity between the sensor connector and the EBCM connector to rule out an internal wire break.

Parts You'll Likely Need

• Rear Wheel Speed Sensor (OEM #84307017 (replaces 84199449)) — This sensor is the most common part to fail in the circuit, after ruling out the EBCM connector issue. Part number 84307017 is specified for the rear left (driver side) on many models including the ZR2, and fits 2017-2022 models. Always verify fitment with your VIN.
  Trusted brands: ACDelco, Delphi, Standard Motor Products, NTK
  OEM price range: $30-$60
  Aftermarket price range: $20-$45
• Electrical Contact Cleaner and Dielectric Grease — Required for addressing the common issue of corrosion in the EBCM connector, as noted in TSB #PIT5499B.
  Trusted brands: CRC, Permatex
  OEM price range: $15-$25
  Aftermarket price range: $10-$20
• EBCM Connector Pigtail (OEM #19178085) — If the EBCM connector is severely corroded and cannot be cleaned, the pigtail harness may need to be cut out and replaced. This part is a connector housing that requires wiring work.
  Trusted brands: ACDelco (GM Genuine Parts)
  OEM price range: $60-$80
  Aftermarket price range: N/A

Related Codes That Often Appear With This One

• C0035 — Left Front Wheel Speed Sensor Circuit fault. Often triggered by the same EBCM connector issue.
• C0040 — Right Front Wheel Speed Sensor Circuit fault. Often triggered by the same EBCM connector issue.
• C0045 — Left Rear Wheel Speed Sensor Circuit fault. Often triggered by the same EBCM connector issue.
• C0050 — Right Rear Wheel Speed Sensor Circuit fault. Often triggered by the same EBCM connector issue.
• U0121 — Lost Communication With Electronic Brake Control Module. This can also be caused by severe corrosion at the EBCM connector.

Technical Service Bulletins (TSBs) & Recalls

• PIT5499B: Mentions that codes including C0055 may be set due to water intrusion or corrosion at the Electronic Brake Control Module connector. It applies to 2015-2016 Colorado/Canyon models and suggests that if corrosion is found, the EBCM and affected terminals should be replaced.

Platform-Specific Known Issues

• A known issue documented in GM Technical Service Bulletin #PIT5499B involves water intrusion into the Electronic Brake Control Module (EBCM) connector, causing corrosion and leading to various ABS-related trouble codes, including C0055.
• On coloradofans.com, a user with a 2016 Colorado Z71 experienced the ABS and Traction Control lights with code C0055. After finding no visible damage, they disconnected the battery, unplugged and inspected the EBCM connector (found it clean), and then re-seated the connector firmly. Upon reconnecting the battery, the code was gone and did not return after a test drive, suggesting a poor connection at the EBCM was the culprit.

Mechanic-Grade Diagnostic Values

• Active Wheel Speed Sensor Power Supply — expected: Battery Voltage (approx. 12V) with key on.. Failure: No voltage at the sensor connector (harness side). Note: The EBCM may cut power when a fault is active. Cycle the key to see a brief voltage pulse to confirm wiring integrity.
• Active Wheel Speed Sensor Signal — expected: Digital square wave signal when viewed on an oscilloscope while spinning the wheel.. Failure: A missing, erratic, or distorted square wave pattern indicates a faulty sensor or tone ring issue.
• Active Wheel Speed Sensor Resistance — expected: These sensors cannot be accurately tested with an ohmmeter; they will typically read as an open circuit (OL) or a very high resistance in the mega-ohm range.. Failure: A specific resistance value is not a reliable indicator of sensor health. Comparing readings between sensors is also not a valid test for this type of sensor.

Hidden / Shadow Codes Worth Checking

• C0055 00: Rear Wheel Speed Sensor Circuit - General Fault. This indicates the EBCM has detected a short to ground, short to voltage, or an open/high resistance in the circuit. This points towards a wiring or sensor electrical failure. (see via Professional scan tools like the GM GDS2 can read these manufacturer-specific symptom bytes.)
• C0055 5A: Rear Wheel Speed Sensor Circuit - Signal Plausibility Failure. This indicates the signal from the sensor is present but erratic, irrational, or does not match the signals from other wheel speed sensors. This often points to a damaged tone ring, excessive wheel bearing play, or debris on the sensor tip. (see via Professional scan tools like the GM GDS2 can read these manufacturer-specific symptom bytes.)

Scan Tool Commands That Help

• GM GDS2 / Tech2 or equivalent professional scanner: EBCM Programming and Setup — This is mandatory after replacing the Electronic Brake Control Module (EBCM). The new module must be programmed with the vehicle's VIN and calibrated for the correct tire size to function.
• GM GDS2 / Tech2 or equivalent professional scanner: Automated Bleed / ABS Bleed — This procedure is required any time the hydraulic lines to the ABS modulator have been opened, such as when replacing the entire EBCM/BPMV assembly. It cycles the internal solenoids to purge trapped air that cannot be removed with a manual bleed.

Wiring & Ground Locations

• EBCM Connector X1 — On the Electronic Brake Control Module, which is mounted to the driver's side frame rail, generally below the driver's door area.. This is the main connector where all wheel speed sensor signals terminate. TSB PIT5499B specifically calls out this connector for water intrusion. All diagnostic wiring tests for the sensor circuits will originate or terminate at this connector.
• EBCM Connector: Pins 2 & 3 (Left Rear) — At the main EBCM connector (X1). Pin 2 is the Left Rear WSS Signal, and Pin 3 is the Low Reference (ground) for that sensor.. These specific pins can be tested for continuity, shorts to ground, or shorts to power when diagnosing a fault in the left rear wheel speed sensor circuit, which can trigger the general C0055 code.
• Ground Splice Pack SP105 — On first-generation models, this was located on the driver's side near the battery, often behind the ABS module. The EBCM ground location on 2nd gen models is also on the driver's side frame rail.. The Electronic Brake Control Module (EBCM) is grounded via this splice pack on related GM platforms. A poor ground at this location can cause a host of intermittent and difficult-to-diagnose ABS faults, including communication errors and false sensor codes.

Real Owner Repair Stories

• YouTube channel 'Wheel Speed ABS Sensor Replacement...' (2018 Chevrolet Colorado Z71 4WD 3.6L) — ABS, Traction, and Stabilitrak warning lights came on after off-roading. ABS would also randomly engage during normal braking.
  ❌ Tried (didn't work) A basic OBD-II scanner could not pull any codes.
  ✅ What actually fixed it A visual inspection revealed the wheel speed sensor wire was frayed near the wheel. Replacing the entire right front wheel speed sensor and harness assembly resolved all symptoms and warning lights.
• PerformanceTrucks.net Forums (2007 Silverado with 4L80E swap (similar EBCM logic)) — C0055 5A (Not Plausible) code sets only during 1/4 to 1/2 pedal acceleration from a complete stop. Scan tool showed rear wheel speed dropping to 0 mph just before the code set.
  ❌ Tried (didn't work) Cleaning EBCM ground, Replacing both transmission speed sensors (ISS and OSS), Replacing both front wheel hub/sensor assemblies
  ✅ What actually fixed it The user's issue was highly specific to their transmission swap and custom tuning. However, the story is valuable as it demonstrates a perfect real-world example of a 'Signal Plausibility Failure' (5A) where the signal was present but dropped out under a specific load condition, which is a classic mechanic-grade diagnostic scenario.

OEM Part Supersession History

• 84199449 → 84307017 — Standard part revision and replacement.
  Heads up: The new part number (84307017) is the correct replacement for the original.