U0155 on 2010-2017 GMC Terrain: Lost Communication with Instrument Cluster Fixes

What's Unique About the 2010-2017 Gmc TERRAIN

For the first-generation GMC Terrain (2010-2017) and its platform-mate, the Chevrolet Equinox, the U0155 code is frequently linked to specific electrical issues beyond just a failed cluster. A key GM Technical Service Bulletin (TSB PIT5422) points directly to water intrusion in the body harness connector X901 as a primary cause for this and other communication codes. This connector is reportedly located in the driver's side footwell area, near the fuse block, making it susceptible to moisture from wet footwear or windshield leaks. This suggests that before replacing the expensive instrument cluster, a thorough inspection of this specific wiring harness connector for corrosion is a critical, vehicle-specific diagnostic step.

Diagnostic Flowchart

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

Symptoms You May Notice

• Instrument cluster is completely dead or works intermittently (no lights, no gauges).
• Gauges for speed, RPM, fuel, or temperature are stuck, erratic, or drop to zero while driving.
• Multiple warning lights (Check Engine, ABS, Airbag, StabiliTrak) are on simultaneously.
• The Driver Information Center (DIC) screen is blank, pixelated, or shows an error message.
• Odometer displays dashes (-------) instead of mileage.
• Interior lights or the power liftgate may not work (as noted in TSB PIT5422).
• Audible chimes for turn signals or warnings may be absent.

Most Likely Causes

1. Blown Fuses 🔴 High Probability The instrument cluster is protected by several fuses in multiple fuse boxes. A simple blown fuse can cut power and cause a communication loss.
   How to confirm: Visually inspect and test the fuses related to the instrument cluster and display. On the 2010-2017 Terrain, check fuses in the passenger side interior fuse box (specifically F18 'DISP' and F37 'IPC/DIC') and the under-hood fuse box (F7, F11, F14, F50). 🎬 Watch: Locate all fuse boxes and the OBD2 port Always check if a fuse blows again, indicating a short.
   Typical fix: Replace the blown fuse. If the fuse blows again immediately, it indicates a short circuit in the wiring that needs to be diagnosed.
   Est. part cost: $1-$10
2. Weak or Dead Battery / Failing Alternator 🟡 Medium Probability Electronic modules require a stable voltage (typically above 12.0V) to communicate properly. Low voltage during startup or while running can cause random communication codes like U0155.
   How to confirm: Test the battery voltage with a multimeter; it should be above 12.4 volts with the engine off. With the engine running, check the alternator output, which should be between 13.5 and 14.5 volts.
   Typical fix: Recharge or replace the battery. If the alternator is not charging correctly, it will need to be replaced.
   Est. part cost: $150-$400
3. Corroded Body Harness Connector (X901) 🟡 Medium Probability A manufacturer TSB (#PIT5422) specifically identifies water intrusion and corrosion in the body harness connector X901 as a cause for U0155 and other communication failures on the 2010 Terrain and similar models. This connector is located in the driver-side kick panel/footwell area, making it vulnerable to moisture.
   How to confirm: Locate and disconnect the body harness connector X901 in the driver's footwell area. Inspect the pins and terminals for any signs of moisture, green or white corrosion, or backed-out pins.
   Typical fix: The connector and any damaged terminals must be professionally cleaned with electrical contact cleaner or replaced. The source of the water leak (e.g., windshield seal, sunroof drain) must be found and sealed to prevent recurrence.
   Est. part cost: $50-$200 for connector repair parts and sealing materials.
4. Faulty Instrument Panel Cluster (IPC) ⚪ Low Probability The internal electronics of the cluster, such as the microcontroller or power supply, can fail over time due to heat, vibration, or component age, causing it to stop communicating on the network. Cracked solder joints on the main circuit board are a common failure point on GM clusters of this era.
   How to confirm: If all power, ground, and network wiring to the cluster test good, the cluster itself is the likely culprit. This is typically the last step 🎬 See this breakdown of common U0155 causes and fixes in diagnosis after ruling out all other possibilities.
   Typical fix: The instrument cluster must be replaced. A new or refurbished unit must be programmed to the vehicle's VIN and mileage by a dealer or qualified shop. Some specialized shops can repair the original cluster by reflowing solder joints.
   Est. part cost: $200-$500 for a remanufactured unit, $600-$900+ for a new OEM part.

Rare But Worth Checking

• CAN Bus Wiring Issues: An open or short in the twisted-pair CAN bus wiring harness can take the cluster offline. This can be caused by chafing against a metal bracket under the dash, damage from a previous repair, or rodent damage.
• Faulty Body Control Module (BCM): While less common, a failing BCM can disrupt network communication and cause other modules, like the IPC, to set communication codes. Symptoms can include erratic lights, door lock issues, or battery drain.
• Aftermarket Device Interference: Poorly installed aftermarket devices like remote starters, alarms, or even OBD-II insurance dongles can interfere with the CAN bus network, causing communication errors.

Diagnosis Steps

1. Read all fault codes from all modules using a capable OBD-II scanner. Note if other 'U' codes are present, which can point to a network-wide issue.
2. Check the battery. Ensure it is fully charged (above 12.4V) and the terminals are clean and tight. Test the alternator's output while the engine is running (should be 13.5-14.5V).
3. Inspect all relevant fuses. In the 2010-2017 Terrain, check fuses F18 ('DISP') and F37 ('IPC/DIC') in the interior fuse box and F7, F11, F14, and F50 in the under-hood fuse box.
4. If fuses are good, inspect the body harness connector X901 for signs of water damage or corrosion, as specified in TSB PIT5422. This connector is located in the driver-side kick panel area.
5. If no corrosion is found, gain access to the back of the instrument cluster. Visually inspect the connector for loose pins, corrosion, or damaged wires.
6. Using a digital multimeter, verify that the cluster is receiving proper power (12V+) and has a solid ground connection at its main connector. A key ground point for the IPC is G103, located on the cowl in the engine bay, above the brake booster.
🎬 Watch: GMC Terrain instrument cluster fuse and relay guide
7. If power and ground are good, test the CAN bus network wires. With the battery disconnected, measure the resistance between Pin 6 (CAN-H) and Pin 14 (CAN-L) of the OBD-II port. It should be approximately 60 ohms. A reading of 120 ohms suggests an open circuit or a missing terminating resistor, while a reading near 0 ohms indicates a short.
8. If all wiring, power, and grounds are confirmed to be good, the Instrument Panel Cluster is likely faulty and requires replacement and programming.

Parts You'll Likely Need

• Fuses — A blown fuse is a simple but common cause for the instrument cluster losing power and communication.
  Trusted brands: Bussmann, Littlefuse
  OEM price range: $1-$5
  Aftermarket price range: $1-$5
• Instrument Panel Cluster (OEM #20907584 (Example for 2012 w/o Lane Departure), 23265866 (Example for 2014-2017)) — If all other causes are ruled out, the cluster's internal electronics may have failed. This is the ultimate fix when the part itself is bad. Part number must be matched exactly.
  Trusted brands: ACDelco (OEM), Dorman (Remanufactured)

Related Codes That Often Appear With This One

• U0078 — Lost Communication With Control Module 'G' - Often cited in the same TSB (PIT5422) related to the X901 connector issue.
• U0140 — Lost Communication With Body Control Module - Indicates a broader network problem, often pointing to a wiring or power supply issue rather than a single failed module.
• U0100 — Lost Communication with ECM/PCM - A general network code that can appear with U0155 if there is a significant network failure or power supply issue.

Technical Service Bulletins (TSBs) & Recalls

• PIT5422: Malfunction Indicator Lamp On, Interior Lamps Inoperative, Lift Gate Inoperative, DTC U0078, U0140, U0151, U0155, U0164, U0198, or U0230. The bulletin directs technicians to inspect body harness connector X901 for water intrusion and corrosion.

Platform-Specific Known Issues

• TSB #PIT5422 documents that on some 2010 models, water can enter the body harness connector X901, causing corrosion and leading to code U0155 and other communication failures. This is a well-known issue for the first-generation Terrain/Equinox platform.
• Forum Experience: Intermittent Cluster Failure: A user on a GM forum described their 2011 Terrain's instrument cluster intermittently going completely dead while driving. After checking fuses and the battery, the dealership diagnosed a faulty Instrument Panel Cluster. The repair involved replacing the cluster and programming it to the vehicle, which resolved all symptoms.

Mechanic-Grade Diagnostic Values

• High-Speed CAN Bus Resistance — expected: ~60 Ω. Failure: A reading of ~120 Ω indicates an open circuit or a missing terminating resistor. A reading near 0 Ω indicates a short between the CAN High and CAN Low wires.
• CAN Bus Voltage (Recessive State) — expected: Both CAN High and CAN Low wires should be at ~2.5V when measured to ground.. Failure: Significant deviation from 2.5V on either line at idle suggests a wiring fault or a module pulling the voltage down.
• CAN Bus Voltage (Dominant State) — expected: During active communication, CAN High should toggle to ~3.5V and CAN Low should toggle to ~1.5V.. Failure: Failure to reach these approximate voltages during communication (best viewed on an oscilloscope) points to a network integrity problem.

Scan Tool Commands That Help

• GM GDS2 (Global Diagnostic System 2): Output Controls / Bidirectional Tests for Instrument Panel Cluster — After confirming power and ground are good but communication is lost, use this to directly command cluster functions (e.g., 'All Gauges Sweep,' 'All Indicators On,' 'Display Test'). If the cluster responds to commands from the scan tool, it proves the cluster's internal processor and displays are functional, pointing the diagnosis toward a network communication wiring or module issue rather than a failed cluster.

Wiring & Ground Locations

• X901 — In the driver's side footwell/kick panel area.. This is a major body harness connector. Per TSB #PIT5422, it is a known point of failure due to water intrusion and corrosion, directly causing U0155 and other communication codes.
• G103 — Located in the engine compartment on the cowl, above the brake booster.. This is a critical ground point that serves the Instrument Panel Cluster (IPC), Body Control Module (BCM), and the Data Link Connector (DLC). A poor connection here can simultaneously disrupt communication from the cluster, the BCM, and prevent a scan tool from communicating properly, mimicking a major network failure.
• Instrument Panel Fuse Block — Located on the passenger side of the center console, behind a removable panel.. Contains key fuses for the Instrument Panel Cluster and Driver Information Center (IPC/DIC) and Display (DISP), which are primary checks for a dead cluster.

OEM Part Supersession History

• Varies → Varies — Part updates and revisions.
  Heads up: Part numbers must be matched exactly. Clusters for vehicles with different options (e.g., with/without Lane Departure Warning) are not interchangeable even if they physically fit. Clusters from the Chevrolet Equinox are also generally not compatible.

Model Year Variations Within This Range

• 2010-2017: While there was a model refresh in 2016, the fundamental electrical architecture and causes for U0155 remained consistent across the first generation. The primary diagnostic steps apply to all years in this range.