U0028 on 2013-2018 Chevrolet Traverse: Infotainment Network Fault Causes and Fixes

What's Unique About the 2013-2018 Chevrolet TRAVERSE

The Traverse from this era shares its infotainment architecture with many other GM vehicles (Buick Enclave, GMC Acadia) which have a known vulnerability in the MOST bus ring design. The system operates as a 'ring,' meaning one failed component can disable the entire network. While some GM trucks are known for a pinched wiring harness causing this code, the Traverse and its platform mates are more commonly cited for individual module failures (like the radio or HMI) breaking the communication loop. GM has issued specific bulletins, like #PIC6073E, that guide technicians on diagnosing this exact code on the MOST bus by using a bypass loop to isolate the faulty module.

Diagnostic Flowchart

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

Generation note: This range covers the end of the first generation (2013-2017) and the start of the second generation (2018). Both generations use a MOST bus architecture for infotainment, and the diagnostic principles are similar. The provided TSB #PIC6073E applies to models up to 2019, indicating the issue and diagnostic procedure span both generations.

Symptoms You May Notice

• Blank infotainment or radio display, especially on startup.
• No audio from the stereo, but vehicle chimes may still work (often rerouted through the instrument cluster).
• Radio or steering wheel controls are inoperative.
• Loss of navigation and hands-free phone functions.
• Dead battery after the vehicle sits for a period of time.
• Audio information page on the Driver Information Center (DIC) is blank.
• Backup camera does not display (or in some cases, is the only thing that displays).

Most Likely Causes

1. Failed Human Machine Interface (HMI) Module 🔴 High Probability The HMI module is the central 'brain' for the infotainment system and a very common point of failure in the MOST network ring across many GM platforms. An internal electronic fault will break the communication loop, causing a blank screen and setting U0028.
   How to confirm: Using a MOST bypass loop tool (like GM's EL-51578), a technician can bypass the HMI module. If other functions return and the U0028 code changes from 'current' to 'history', the HMI module is faulty. Bypassing the HMI will result in an inoperative display, but audio may return, confirming the diagnosis.
   Typical fix: Replace the HMI module. This part is VIN-locked and requires programming by a dealer or a qualified independent shop with GM software. Ensure the replacement part number matches the original, as there are different versions for navigation and non-navigation systems.
   Est. part cost: $250-$600
2. Failed Radio/Tuner Module 🟡 Medium Probability The radio acts as the 'master' of the MOST bus. An internal failure can prevent the entire network from initializing, causing a total communication loss and setting code U0028. This is a common failure point if symptoms include a total loss of audio, including door chimes.
   How to confirm: This is typically diagnosed through a process of elimination. The radio cannot be bypassed with the standard loop tool. If bypassing all other modules on the MOST ring does not resolve the code, the radio becomes the primary suspect. A professional scan tool may also show the radio is not communicating or has logged the U0028 code itself.
   Typical fix: Replace the radio/tuner module. This component is located behind the center stack controls and may also require programming to the vehicle. 🎬 Watch: How to remove the factory stereo in a Traverse.
   Est. part cost: $200-$700
3. Failed Media Disc (CD/DVD) Player 🟡 Medium Probability Even if never used, the CD player is an active node in the MOST communication ring. Its internal electronics can fail, breaking the circuit and bringing the entire infotainment system down.
   How to confirm: This is one of the easiest modules to test. Use a MOST bypass loop to jump the connection at the CD player. If the radio screen and audio come back to life, the CD player is the faulty part. A technician on the iATN network confirmed this failure mode on a similar GM vehicle.
   Typical fix: Replace the CD player or leave it bypassed if you don't use it. Replacing it is often a plug-and-play operation, though some may require programming.
   Est. part cost: $100-$300
4. Damaged MOST Bus Wiring or Connectors ⚪ Low Probability Unlike some GM trucks and SUVs known for a specific pinched wire location, the Traverse is not widely cited for a particular wiring chafe point causing U0028. However, any damage, corrosion, or loose connection in the fiber-optic or twisted-pair MOST bus wiring can break the ring and cause the code. A loose blue connector at the HMI module has been cited by some owners as a cause.
   How to confirm: A visual inspection of the wiring behind the radio, HMI module, and amplifier is the first step. If bypassing all modules doesn't resolve the code, a wiring fault is likely and requires point-to-point testing of the circuit, as outlined in TSB PIC6073E.
   Typical fix: Repair the damaged section of the wiring harness and ensure all connectors are clean and secure.
   Est. part cost: $10-$50

Rare But Worth Checking

• Failed Instrument Panel Cluster (IPC): The IPC is also a module on the MOST bus. While a less common failure point for this specific issue, an internal fault in the cluster can break the communication ring and cause a U0028 code. It would be diagnosed using the same bypass loop procedure; TSB PIC6073E notes that bypassing a faulty IPC will cause the DIC and steering wheel controls to be inoperative but may restore other functions.
• Failed Amplifier: If equipped with a premium sound system (Bose, etc.), the amplifier is another node in the MOST ring. It can fail and break the communication loop. On some other GM models, this is due to water intrusion in the trunk area, so it's worth checking its location for any signs of moisture. Bypassing the amplifier will restore the screen but there will be no audio.

Diagnosis Steps

1. Perform a full vehicle scan. If any module-specific communication codes (U0184, U0186, U0155) are present, diagnose those first as they can pinpoint the faulty module.
2. Check for basic power and ground issues at the fuses and module connectors before assuming a network fault. TSB PIC6073E states this is a probable cause.
3. Visually inspect the wiring and connectors at the most accessible MOST bus modules (Radio, HMI, CD Player) for obvious damage or looseness.
4. Using a professional scan tool (like GM's GDS2), check the radio module for the 'Surrogate MOST Master Node Upstream Position' data parameter. This can help identify which module is just before the communication break.
5. Begin diagnosis using a MOST bus bypass loop tool (GM EL-51578). Start by bypassing an easily accessible module, like the CD player or HMI module (often behind the glove box).
6. After bypassing a module, cycle the ignition and check if infotainment functions return and if the U0028 code changes from 'Current' to 'History'.
7. If the system remains down, remove the first bypass loop and move to the next module in the ring and repeat the process. The modules in the ring can include the Radio, HMI, IPC, Amplifier, and CD Player.

Parts You'll Likely Need

• Human Machine Interface (HMI) Module (OEM #22953962, 84331775) — This is the 'brain' of the infotainment system and a very common failure point that breaks the MOST communication ring, causing a U0028 code. Part numbers vary by year and whether the vehicle has factory navigation.
  Trusted brands: ACDelco
  OEM price range: $400-$700
  Aftermarket price range: $250-$500
• Radio/Tuner Module (OEM #23130132, 13592804, 42554703) — As the master of the MOST bus, an internal failure in the radio will take down the entire network. It's often diagnosed after other modules are ruled out. Part numbers vary significantly by year and option codes.
  Trusted brands: ACDelco
  OEM price range: $200-$700
  Aftermarket price range: $150-$500
• MOST Bus Bypass Loop (OEM #EL-51578) — This is not a replacement part, but an essential diagnostic tool required to properly isolate the failed module in the MOST bus ring.
  Trusted brands: Bosch/GM Essential Tools
  OEM price range: $15-$50
  Aftermarket price range: $10-$30

Related Codes That Often Appear With This One

• U0029 — This code often appears with U0028. While U0028 indicates a complete break in the MOST ring, U0029 ('Vehicle Communication Bus A Performance') can indicate the ring has integrity but a specific module is not communicating correctly. Seeing both helps a technician diagnose the fault.
• U0184 — This code means 'Lost Communication With Radio'. It can be a direct result of the U0028 fault, as the MOST bus failure prevents other modules from communicating with the radio. GM documentation advises diagnosing specific communication loss codes like this *before* diagnosing the general U0028.
• U0186 — This code means 'Lost Communication With Amplifier'. Similar to U0184, this points towards the amplifier as a potential source of the MOST bus failure.
• U0155 — This code means 'Lost Communication With Instrument Panel Cluster (IPC)'. If this code is present with U0028, it strongly suggests the IPC is the module that has failed and brought down the network.

Technical Service Bulletins (TSBs) & Recalls

• PIC6073E: The primary TSB for diagnosing U0028 on the MOST bus. It details the use of the EL-51578 bypass tool kit and advises checking for basic power/ground faults before condemning a module.
• PI1149A: An informational bulletin for intermittent blank displays and MOST bus diagnostics. It notes that a blank screen with no audio on startup is a classic sign of the MOST bus being down and a U0028 fault.
• PIT4649D: Discusses parasitic battery drain caused by modules (like those on the infotainment bus) failing to go to sleep, a potential side effect of a U0028 fault.

Platform-Specific Known Issues

• Failure After a Jump-Start or Battery Replacement: Some owners report the U0028 fault and resulting black screen appear immediately after the vehicle's battery has been replaced or jump-started. The voltage spike or interruption can sometimes cause an already-weak module on the MOST bus to fail completely.
• Diagnostic Confusion with Door Chimes: A key diagnostic clue mentioned by technicians is the status of the door chimes. If the screen is black and there are absolutely no chimes, the Radio/Tuner module is a strong suspect. If chimes are still heard (often from the instrument cluster), the HMI module or another module on the ring is more likely the cause, as the radio is still partially functioning.

Mechanic-Grade Diagnostic Values

• Module Power Supply Voltage (Key On) — expected: 12.0 - 14.5 V. Failure: Voltage below 12.0V suggests a power supply or ground issue to the module, which must be fixed before diagnosing the MOST bus.
• Module Power Circuit Load Test — expected: Able to light a 2-amp test bulb (for a 20-amp fused circuit). Failure: If the test bulb does not light brightly, it indicates high resistance in the power feed wire or connector that a simple voltage test might miss.
• Module Wake-Up Signal (ECL) — expected: Able to light a low-current (e.g., 50mA) test light.. Failure: No voltage or inability to light the test light indicates the master (radio) is not sending the wake-up signal or there is a break in the circuit.

Hidden / Shadow Codes Worth Checking

• U0028 sym00: This is a symptom byte indicating a MOST bus communication fault. GM diagnostic procedures rely on this code's status (Current or History) to confirm if a faulty module has been successfully bypassed. (see via GM GDS2 (Global Diagnostic System 2) or an equivalent professional scan tool.)
• Surrogate MOST Master Node Upstream Position (Data PID): This is not a code, but a critical data parameter in the Radio module. When a fault occurs, the module after the break becomes a 'surrogate master'. This PID displays a number corresponding to the ring position of the module *before* the break, directly pointing the technician to the faulty component or wiring section. (see via GM GDS2, navigate to Radio > Data Display. Some 2013-2014 models may require a radio software update to make this parameter visible.)

Scan Tool Commands That Help

• GDS2 (Global Diagnostic System 2): Radio > MOST Data — This is the primary diagnostic screen for this fault. Use it to monitor the 'Number of MOST Communication Breaks' and the 'Surrogate MOST Master Node Upstream Position' to pinpoint the location and nature of the fault before physically touching the vehicle.
• GDS2 (Global Diagnostic System 2): Clear All DTCs — After installing a MOST bypass loop on a suspected faulty module, clear all codes and cycle the ignition. Then, re-check the status of U0028 sym00. If it has changed from 'Current' to 'History', the bypassed module is confirmed as the cause.
• SPS (Service Programming System): Radio (Tuner) Programming — On 2013 and some 2014 models, if the 'Surrogate MOST Master Node Upstream Position' parameter is missing in GDS2, the radio must be reprogrammed with the latest software to make this critical diagnostic aid visible.

Wiring & Ground Locations

• G302 — On a 2015 Traverse, located at the base of the right-hand (passenger side) B-pillar. On other GM platforms, it can be under the center console.. This ground point is known to be used by the radio amplifier. A poor connection here can prevent the amplifier from powering on, breaking the MOST ring and causing a U0028 code.
• G103 — Commonly located on the cowl in the engine compartment, above the brake booster.. This is a major body ground point that serves multiple interior modules, including the Radio and Instrument Panel Cluster (IPC), both of which are on the MOST bus. A fault here can cause a U0028 and other seemingly unrelated codes.
• HMI Module Connectors — Behind the glove box, connected to the HMI module.. The main blue connector for the MOST bus at the HMI module can become loose, particularly after a cabin air filter change. Simply reseating this connector has been reported to fix the U0028 code and blank screen.

Real Owner Repair Stories

• iATN (International Automotive Technicians Network) Forum (2015 Chevrolet Silverado (similar MOST system)) — MyLink display was dark, radio would not play, control buttons were non-functional. Codes U0028 (current) in radio and U0029 (current) in HMI.
  ❌ Tried (didn't work) The technician correctly avoided random parts replacement and went directly to scan tool data.
  ✅ What actually fixed it The technician used a GDS2 scan tool and observed the 'Surrogate MOST Master Node Upstream Position' data parameter showed a value of '2'. Knowing the ring order was Radio(1)>CD(2)>HMI(3)>IPC(4), this pointed directly to the CD player (node 2) as the fault. The technician bypassed the CD player with a jumper, which restored all functions. The root cause was an internal failure of the CD player.
• Reddit user @spider_gumdrop (2017 Chevrolet Volt (similar MOST system)) — Infotainment display went dark, persistent U0028 code.
  ❌ Tried (didn't work) Replacing the infotainment display screen., Installing a used HMI module, which resulted in a 'Theft Locked' message because its VIN did not match the vehicle.
  ✅ What actually fixed it The owner purchased a brand new HMI module and used a GM MDI2 interface with a paid subscription to the Service Programming System (SPS) to program the new module to the vehicle's VIN, which resolved the issue.
• YouTube video by JK-Baljit Johal (GMC Acadia (sister platform to Traverse)) — Radio display worked, but there was no audio from the speakers.
  ✅ What actually fixed it The amplifier module, located under the driver's side dashboard near the steering column, had failed. Replacing the amplifier restored all audio functions.

"I Checked Everything" — The Actual Cause

• The network equivalent of a 'smoke test clean' scenario is when a technician uses a MOST bypass loop on every module in the ring, but the U0028 code remains current and the system does not power on. According to GM TSB PIC6073E, if bypassing all suspect modules does not resolve the fault, the problem is not a module but the wiring itself. The technician must then check the MOST bus circuits and connectors between the modules for opens, shorts to power/ground, or high resistance.

OEM Part Supersession History

• Multiple (e.g., 23212438) → Multiple (e.g., 84156699, 84364934) — GM frequently updates HMI modules with hardware and software revisions to fix bugs and improve performance.
  Heads up: According to specialty suppliers, ordering a replacement HMI by part number is unreliable. It is critical to order based on the vehicle's model year, generation, and RPO codes for features like Navigation (IO5/IO6) vs. Non-Navigation (IO4/IOB). A supplier will then provide the latest correct, superseded part number. Installing the wrong version can lead to function loss or a 'Theft Locked' state.

Model Year Variations Within This Range

• 2018: The 2018 model year marked a full redesign onto the C1 platform. It features a completely different infotainment system (Chevrolet Infotainment 3) with a new screen design, different HMI module (sometimes called a CSM), and a new 9-speed transmission. While it still uses a MOST bus, the electronic modules are not interchangeable with the 2013-2017 first-generation models.
• 2016: Due to a documented supply issue, some 2016 GM vehicles were built with the older HMI 2.0 module (used in 2015) instead of the expected HMI 2.5 module. These vehicles lack Apple CarPlay/Android Auto. If the HMI fails on one of these specific vehicles, it must be replaced with another HMI 2.0 module, not the 2.5 version that is standard for most 2016s.
• 2013-2014: The radio software on some early models in this range may not display the 'Surrogate MOST Master Node Upstream Position' parameter in the GDS2 scan tool. TSB PI1149A advises that the radio (tuner) must be reprogrammed with the latest calibrations via SPS to make this critical diagnostic parameter visible.