U1345 on 2017-2019 Chevrolet Traverse: Active Grille Shutter Fault Causes and Fixes

What's Unique About the 2017-2019 Chevrolet TRAVERSE

The 2017-2019 Traverse model years span two different vehicle generations: the first-gen 2017 model on the Lambda platform and the second-gen 2018-2019 models on the C1XX platform. Despite the architectural differences, both generations use an active grille shutter system to improve fuel economy. This system has a known vulnerability across both platforms. The electrical connectors for the shutter actuators are located in an area prone to water and road spray exposure, leading to corrosion and communication failures. General Motors has acknowledged this issue through multiple Technical Service Bulletins, making it a well-documented platform-specific problem rather than a random component failure.

Diagnostic Flowchart

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

Generation note: The specified year range covers two generations: the 2017 model is the last year of the first generation (Lambda platform), while the 2018-2019 models are the beginning of the second generation (C1XX platform). Despite the generational change, GM issued TSBs that cover models from both generations, indicating the active grille shutter connectors are a common point of failure on both designs. TSB 19-NA-215 specifically targets the 2018-2019 C1XX models and their Buick Enclave platform mate.

Symptoms You May Notice

• Check Engine Light (Service Engine Soon lamp) is on
• Remote start may be disabled.

Most Likely Causes

1. Water Intrusion in Active Grille Shutter Connector(s) 🔴 High Probability The location of the upper and lower shutter connectors makes them susceptible to water and road spray. The factory seals may not be sufficient over time, leading to corrosion on the connector pins.
   How to confirm: Visually inspect the upper and lower active grille shutter electrical connectors for moisture, white or green corrosion, or backed-out pins. This is the primary inspection step recommended by GM TSBs #PIT5609A and #19-NA-215. The connector is often gray and located on the passenger side of the shutter assembly.
   Typical fix: Disconnect the connector, clean the pins and terminals thoroughly with an electrical contact cleaner, allow it to dry completely, apply dielectric grease to the seal, and reconnect securely. If the connector or pins are severely corroded or damaged, the connector pigtail will need to be replaced.
   Est. part cost: $5-$25 for cleaner and grease; $25-$50 for a replacement pigtail connector.
2. Damaged Wiring Harness 🟡 Medium Probability The wiring harness leading to the shutters can be chafed, pinched, or cut against the radiator support or other components in the front of the engine bay. This can happen from vibration or improper routing.
   How to confirm: Carefully inspect the wiring harness leading to both shutter connectors for any signs of rubbing, pinching, or breaks in the insulation. TSB #19-NA-215 specifically shows examples of cuts or nicks near the connectors as a possible cause. Other GM TSBs for similar LIN bus faults also point to pinched or rubbed-through wiring as a common cause.
   Typical fix: Repair the damaged section of wire using solder and heat-shrink tubing or appropriate crimp connectors. Reroute the harness slightly if possible to prevent future damage.
   Est. part cost: $5-$15 for wire repair supplies.
3. Failed Active Grille Shutter Actuator ⚪ Low Probability While less common than wiring issues for a U1345 code, the electronic motor that drives the shutters can fail internally. This can be due to the motor burning out or from physical damage caused by debris (ice, rocks) striking the shutter assembly.
   How to confirm: After confirming the wiring and connectors are good, use a bi-directional scan tool to command the shutters to open and close. If they do not respond, and power and ground are verified at the actuator, the actuator has failed.
   Typical fix: Replace the active grille shutter assembly, which includes the actuator motor.
   Est. part cost: $150-$300 for an aftermarket assembly; $350-$500 for an OEM assembly.

Diagnosis Steps

1. Verify the presence of code U1345 with an OBD-II scanner. Note any other codes like U0284 or U0285.
2. Gain access to the front of the radiator. This may require removing the upper radiator air deflector (held by push pins).
3. Locate the electrical connectors for the upper and lower active grille shutter assemblies. The upper connector is typically on the passenger side.
4. Disconnect each connector and thoroughly inspect for any signs of water intrusion, corrosion (green or white powder), or damaged/bent pins.
5. If corrosion is found, clean the connector terminals on both the harness side and the actuator side using a dedicated electrical contact cleaner and a small brush. Let it dry completely.
6. If no corrosion is found, inspect the wiring harness leading to the connectors for any signs of chafing, pinching, or physical damage, paying close attention to where it routes near the radiator support. TSB #19-NA-215 specifically calls out looking for cuts or nicks in the wire insulation.
7. Before reconnecting, apply a small amount of dielectric grease to the connector seal to help prevent future water intrusion.
8. Reconnect the connectors firmly until they click.
9. Clear the trouble codes with the scanner and start the vehicle to see if the code returns. Check if remote start functionality is restored.
10. If the code returns immediately, and the wiring is confirmed to be intact, use a bi-directional scan tool to command the shutters open and closed. If they fail to respond, the active grille shutter actuator is the most likely point of failure.

Parts You'll Likely Need

• Electrical Contact Cleaner & Dielectric Grease — This is the first and most common fix, used to clean corroded connectors that cause the communication loss.
  Trusted brands: CRC, Permatex
  Aftermarket price range: $10-$20
• Forward Lamp Wiring Harness Connector Kit (OEM #19352416) — If the original connector or its pins are too damaged by corrosion to be cleaned, this kit is used to replace the harness-side connector. This part number is specified in TSB #19-NA-215.
  Trusted brands: ACDelco
  OEM price range: $30-$50
  Aftermarket price range: $20-$40
• Radiator Shutter Harness Connector Pigtail (OEM #19330674) — An alternative pigtail connector for repairing a damaged harness-side plug for the active grille shutter.
  Trusted brands: ACDelco
  OEM price range: $35-$55
  Aftermarket price range: $25-$45
• Active Grille Shutter Assembly (OEM #84393409) — If the wiring is good but the actuator motor has failed, the entire shutter assembly must be replaced. Part numbers can vary between upper and lower shutters.
  Trusted brands: ACDelco, Dorman, TRQ
  OEM price range: $350-$500
  Aftermarket price range: $150-$300

Related Codes That Often Appear With This One

• U0284 — This code specifically means 'Lost Communication with Active Grille Air Shutter Actuator 1'. It is a more specific version of the U1345 LIN Bus fault and often appears alongside it, confirming the issue is with the shutter system.
• U0285 — This code means 'Lost Communication with Active Grille Air Shutter Actuator 2' (for vehicles with separate upper and lower shutters). It can appear with U1345 if the lower shutter has the communication issue.

Technical Service Bulletins (TSBs) & Recalls

• 19-NA-215: Supersedes previous bulletins and advises inspecting for water intrusion or harness damage at the active grille shutter connectors on 2018-2019 Traverse and Buick Enclave models. It provides a part number (19352416) for a replacement connector kit.
• PIT5609A: Preliminary information bulletin that first identified the issue of an SES lamp with DTC U1345 and pointed technicians to inspect the aero shutter connections for water.
• PIT5609: The original preliminary bulletin highlighting the link between U1345 and water in the aero shutter connections.

Platform-Specific Known Issues

• A known issue documented in GM TSBs #PIT5609, #PIT5609A, and #19-NA-215 is water intrusion into the upper and lower aero/active grille shutter connectors, causing corrosion and setting DTC U1345.
• TSB #19-NA-215 also specifically instructs technicians to inspect the wiring harness for physical damage like cuts or nicks near the connectors, indicating this is a common point of failure beyond just water intrusion.

Mechanic-Grade Diagnostic Values

• LIN Bus Voltage (at rest) — expected: Approximately 12V (or battery voltage). Failure: Voltage significantly lower than battery voltage when no communication is active.
• LIN Bus Voltage (communicating, measured with scope) — expected: Signal fluctuates, but should remain approximately 1V above ground at its lowest point and 1V below system voltage at its highest.. Failure: A flat line, a signal shorted to ground (0V), shorted to power (~12V+), or a distorted waveform (described as 'ocean waves' instead of square waves) indicates a fault.
• LIN Bus Voltage (communicating, measured with DMM on Peak Min/Max) — expected: Max voltage will be approx. 12V, Min voltage will be approx. 1V.. Failure: Readings outside this range, or a steady voltage between 7-9V (if not using Peak Min/Max), suggest a problem.

Hidden / Shadow Codes Worth Checking

• U1345 - LIN Bus 1 or LIN Bus 21: Technician may find DTC U1345 described as 'Engine Control Module LIN Bus 1' or 'Bus 21'. This is a known variation in how scan tools report the same fault on this platform. (see via This variation may appear on professional scan tools like the GM GDS2.)

Scan Tool Commands That Help

• GDS2 (GM Global Diagnostic System 2) or equivalent bidirectional scanner: Active Grille Air Shutter Position Command — After verifying wiring and connectors are intact, this command is used to functionally test the shutter actuator. The technician can command the shutters to open (100%) and close (0%) to see if the motor responds. If it does not move, the actuator has likely failed.

Wiring & Ground Locations

• Active Grille Shutter Connector (Upper/Lower) — In-line connector for the engine wiring harness to the active grille air shutter actuator. On SUVs like the Traverse, this is designated as X604A.. This is the primary point of failure due to water intrusion and corrosion, as cited in multiple TSBs. It is the first place to inspect.
• Circuit 4621 — This is the specific LIN bus circuit wire that connects the ECM to the active grille shutter. It is a single wire for communication.. A break, short to ground, or short to power on this specific circuit will cause the U1345 code. TSBs instruct technicians to check the integrity of this circuit.
• Fuse F61 — In the underhood fuse block.. Fuse F61 supplies power to the Air Shutter, among other components. While a blown fuse is not the most common cause for a communication code, it should be checked as part of a complete electrical diagnosis.

Real Owner Repair Stories

• Reddit user LJFMX (2020 Chevrolet Colorado V6 (similar LIN bus architecture)) — Check Engine Light came on 4 days after purchase. Code U1345 was present by itself. Remote start was disabled. Engine ran fine.
  ❌ Tried (didn't work) Clearing the code (it came back immediately).
  ✅ What actually fixed it The user took the front bumper off and found a 'burnt out connector' on the lower right-hand side going to the active shutters. They removed the bad connector, soldered the wires directly, and the problem was resolved.

OEM Part Supersession History

• 19352416, 19330674, 19371196 → 85519071 — Standard part consolidation and updates by the manufacturer.
  Heads up: The new part number 85519071 replaces the previous connector pigtail/kit part numbers cited in older service bulletins for this repair.