This service bulletin provides information on the proper Reflective High Temperature Heat and/or Insulating Tape to use for certain repairs, such as Wiring Harness Repairs.
full bulletin at NHTSA ↗2018 GMC Terrain electrical problems
severe Owners of the 2018 GMC Terrain have filed 29 NHTSA complaints about the electrical, typically surfacing around 30,000 miles at roughly $850 to repair (U.S. federal records, as of July 2026). Source: NHTSA Office of Defects Investigation. See electrical across all vehicles →
Failure mileage
Complaints
29
Recalls
0
Avg fix
$850
| Model year | electrical complaints |
|---|---|
| 2014 Terrain | 27 |
| 2015 Terrain | 25 |
| 2016 Terrain | 6 |
| 2017 Terrain | 6 |
| 2018 Terrain (this page) | 29 |
| 2019 Terrain | 23 |
| 2020 Terrain | 21 |
| 2021 Terrain | 5 |
| 2022 Terrain | 8 |
1crash
1fire
When does it fail?
Of the 29 electrical complaints filed for the 2018 GMC Terrain, here's the actual mileage breakdown — failures cluster heaviest at 0-25,000 mi.
0-25k
25-50k
50-75k
75-100k
100-125k
125-150k
150k+
Each bar shows the share of total complaints filed at that mileage range. Peak failure window highlighted. Some owners report problems earlier; some make it well past 150,000 miles symptom-free. Maintenance habits and driving conditions shift the curve as much as mileage alone.
What stands out
Owners have filed 29 electrical complaints with NHTSA against this vehicle, but no formal recall covers the issue — the federal record reflects what manufacturers have admitted, not everything owners are reporting.
Among the 16 model years of GMC Terrain in our records for electrical problems, this one ranks #2 by owner-complaint volume.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering electrical on this vehicle — documented repair instructions, service campaigns, or warranty extensions sent to dealers. A TSB isn't a recall (it's not a free safety remedy), but it's the manufacturer acknowledging the issue and how to fix it.
The intent of this service bulletin is to identify aftermarket ALDL or DLC interface devices as potential sources for causing multiple customer concerns that do not have other diagnostic methods to identify them.
full bulletin at NHTSA ↗This service bulletin provides information for dealers/technicians on Service Programming System (SPS) Error Codes E4398, E4399, E4401, E4403, M4404, M4413, M6954, M6955, E4414, E4423, E4491, E4492, or E6961 and resolution information.
full bulletin at NHTSA ↗This service bulletin provides repair information to correct a customer concern of Vehicle Will Lock and Unlock (Active Functions Work) but Will Not Crank or Start (Loss of Passive Functions Do Not Work).
full bulletin at NHTSA ↗This service bulletin provides repair information to correct a customer concern of No Crank, No Start, Quick Start/Stall, No FOB Detected, Key FOBs Inoperative, B3924 00, B3925 00, B3926 00, B3927 00, B3928 00 Set.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
The 2018 GMC Terrain shows a cluster of serious electrical failures affecting core safety systems. Multiple owners report abrupt, complete engine shutdowns while driving—the vehicle goes inert with doors locked and unable to shift into neutral, stranding drivers on busy highways and requiring emergency services. GM eventually replaced the ECM (Engine Control Module) in affected vehicles, but not before owners experienced dangerous situations.
Brake system failures represent another critical pattern. Several owners report the brake vacuum pump failed without warning, causing complete loss of braking power on highways. These aren't recalls on the Terrain despite similar failures in other GM vehicles. One owner needed a $2,500 repair after the pump exploded; another paid over $1,700 for brake work.
The infotainment system is plagued by screen failures (black or white screens, losing backup camera feed) and audio malfunctions (radio changing stations by itself, refusing to shut off when the vehicle is powered down). One owner reports GMC acknowledged the issue but has no fix.
Electrical harness corrosion keeps appearing—door locks becoming intermittent, wiring shorting after water intrusion or dealer car washes. Other electrical gremlins include dashboard warning lights activating incorrectly, the stability control system causing unintended shutdowns, start/stop restart failures even after battery replacement, and horn failures. An engine block heater recall remains unresolved after six months due to parts unavailability.
Same GMC Terrain electrical reports on nearby years: 2015 · 2019 · 2020
Failure modes owners describe
Complete vehicle shutdown/lockdown
Engine and all electrical systems shut down abruptly while driving or at stop, leaving the vehicle inert with doors locked and unable to shift to neutral. Owners report inability to exit the vehicle or move it to safety.
When: Variable mileage; one case at 55K miles, others undisclosed. Recurring across multiple time periods for affected owners.
Symptoms owners cite: Engine shuts off completely while driving at various speeds; All electrical power lost; unable to unlock doors or windows; Vehicle will not shift out of park or into neutral; Dashboard lights illuminate before shutdown in some cases; Service Stabilitrak warning appears prior to shutdown in at least one case; Vehicle must be towed; unable to be moved by driver
Codes mentioned: Service Stabilitrak (related symptom, not direct cause)
Repairs/costs cited: ECM (Engine Control Module) replacement reported in two cases; one also mentions computer harness replacement. Dealer service required; vehicle towed for repair.
Recalls/TSBs owners mention: ECM replaced by GM; no recall noted. One case: dealer determined ECM was cause after difficult diagnosis. Service bulletin on electrical harness received by dealer in another case.
Brake vacuum pump failure
Brake vacuum pump failure results in sudden loss of braking power and extremely hard brake pedal, creating immediate highway safety hazard without warning.
When: Occurred while traveling on interstate (one case); no mileage provided. Another case mentions Service Brake Assist warnings appearing repeatedly after auto-stop engagement.
Symptoms owners cite: Brake pedal becomes extremely hard to press; Sudden complete loss of braking power; Longer stopping distance required; No brake boost from booster; Vacuum pump described as 'blown up' or exploded; Service Brake Assist warning light in some cases
Codes mentioned: Service Brake Assist (warning indication)
Repairs/costs cited: Brake vacuum pump replacement required. Repair estimate cited: $2,500 in one case; $400 cited in another. One owner paid over $1,700 for brake service with pump described as blown.
Recalls/TSBs owners mention: No recall exists for this issue on the Terrain, despite similar problems being reported in other GM vehicles. One case notes dealer familiar with issue but unwilling to cover cost under warranty.
Infotainment system malfunction (screen failure and audio issues)
Touchscreen display goes black or white randomly, radio changes stations involuntarily, GPS fails, backup camera disabled, and audio controls become unresponsive. System malfunctions while driving, creating distraction and safety hazard.
When: Recurring; one case radio replaced then failed again within one month. Mileage approximately 77,000 in one case.
Symptoms owners cite: Screen goes completely black or white at random times; Backup camera disappears when screen fails; Radio switches between AM and FM involuntarily; Radio will not turn off when vehicle is powered off; Radio plays random stations when vehicle is off; GPS screen goes blank during navigation; Touchscreen becomes unresponsive; cannot shut off system; White screen reflection on windshield severe enough to prevent safe driving in evening; Audio buttons on steering wheel do not change songs (Apple Play)
Repairs/costs cited: Radio/infotainment unit replaced in at least one case; failure recurred within one month. Multiple software updates attempted without resolution.
Recalls/TSBs owners mention: GMC acknowledged knowing about the issue but stated they do not know why or have a fix. Dealer unwilling to address as safety concern.
Door lock electrical failure
Door locks become intermittent or completely inoperable. Owners locked out of vehicle or unable to lock doors from inside. Corrosion found on electrical harness inside door.
When: Recurring issue; one owner also replaced electrical harness in rear bumper 18 months prior due to corrosion.
Symptoms owners cite: Door locks work only occasionally without apparent reason; Owner locked out of vehicle multiple times; Interior door lock button will not lock or unlock doors; Unable to lock vehicle from inside; No dashboard warning lights present
Repairs/costs cited: Electrical harness corrosion found in passenger front door. Harness replacement cost: $500; dealer would not cover under warranty. Previous rear bumper harness also replaced for corrosion.
Recalls/TSBs owners mention: Service bulletin received by dealer on electrical harness issue, but dealer refused warranty coverage.
Electrical harness corrosion and water intrusion
Electrical harnesses corrode and short out due to water intrusion or inadequate weather sealing. Multiple system failures result, including navigation, sunroof, and general electrical malfunction.
When: One case: rear side windows in hatch area leaked; timing not specified. One case: wiring harness shorted after dealer car wash at delivery.
Symptoms owners cite: Visible corrosion on electrical harness; Navigation system malfunction; Sunroof inoperable; Multiple electrical systems fail; Wiring harness shorts after water exposure
Repairs/costs cited: One case required rear bumper electrical harness replacement for corrosion; another case required front door harness replacement ($500). Water intrusion led to spare tire compartment filling with 3-4 gallons of water.
Recalls/TSBs owners mention: None explicitly noted.
Start/stop and starting system failure
Auto start/stop feature fails to restart engine reliably. Vehicle requires extended cranking attempts or jump-start to restart after stop-start event. Battery replacement did not resolve issue.
When: Occurred at various points: stop-light, intersection, after short drive. One case had multiple failures over consecutive days.
Symptoms owners cite: Start/stop engages but vehicle will not restart; Requires multiple attempts (30+ minutes) to restart engine; Remote start fails to restart vehicle; Engine starts only after extended cycling through start procedure; Jump-start attempted without success; Hesitation before engine starts
Repairs/costs cited: New battery installed; did not resolve issue. Vehicle returned to dealer with problem persisting after battery replacement.
Recalls/TSBs owners mention: None noted; issue remained unresolved after dealer service.
Stability control system malfunction
Service Stabilitrak warning and related stability control system failure causes vehicle to shut down and enter neutral while driving. Multiple warning lights illuminate on dashboard. Issue occurs repeatedly over short periods.
When: Occurred 5 times within 2-week period at 55K miles. Prior incidents at 11K and 27K miles on same vehicle.
Symptoms owners cite: Service Stabilitrak warning light illuminates; Nearly all dashboard warning lights illuminate simultaneously; Vehicle shifts itself into neutral; Engine shuts off while driving; Occurred while turning in traffic and on highway
Codes mentioned: Service Stabilitrak
Repairs/costs cited: Front right wheel sensor replaced by dealer; failure recurred immediately after leaving dealership lot. Vehicle shut off twice after sensor replacement on same day.
Recalls/TSBs owners mention: Dealer replaced wheel sensor; issue persists, indicating sensor replacement did not address root cause.
Engine and transmission performance issues
Severe engine performance and transmission issues present from delivery. Vehicle shakes, surges erratically, will not exceed 33 mph, RPM fluctuates wildly. Multiple components malfunction simultaneously.
When: Began at delivery (day one); worsened at 5,500 miles after 6-7 months of ownership.
Symptoms owners cite: Weird noise in engine/transmission area from delivery; Vehicle does not respond or perform well; Vehicle only runs maximum 33 mph; Shaking and vibration; RPM goes wild; Vehicle slips out of gear and shifts into overdrive randomly; No acceleration response despite pressing gas pedal nearly to floor; Abrupt rapid acceleration after delay; Burning rubber smell from under hood
Repairs/costs cited: Dealer gave multiple different excuses; eventually suggested transmission issue but offered no repair. More time spent at dealership than with owner.
Recalls/TSBs owners mention: GM opened ticket but stated they could not do anything about the issue. Owner told to deal with the problem themselves.
Warning light and instrument cluster malfunction
Instrument panel warning lights activate inappropriately; gauges fluctuate erratically; multiple safety system warnings appear simultaneously with no apparent cause. Lane change alert and collision warning systems malfunction.
When: Occurred at 60 mph in one case, 30-40 mph in another. Failure mileage not provided for lane change alert case.
Symptoms owners cite: Instrument panel warning lights activate and gauges fluctuate; Vehicle experiences acceleration, braking, and steering movement after warning activation; Multiple warning messages appear: Stabilitrak unavailable, collision warning unavailable, lane change alert unavailable, transmission service; Transmission shifts erratically after warning activation; Lane change alert does not operate as intended; Driver alert warning system fails to operate; Service ESC warning appears after auto-stop engagement
Codes mentioned: Stabilitrak unavailable, Collision warning unavailable, Lane change alert unavailable, Transmission service, Service ESC
Repairs/costs cited: Cause could not be determined by dealer in one case. No repair attempted.
Recalls/TSBs owners mention: Manufacturer stated vehicle was performing as intended. No action taken in lane change alert case.
Horn inoperative
Horn does not function. No warning light illuminates.
When: Mileage not provided.
Symptoms owners cite: Horn inoperable; No warning light illuminated
Repairs/costs cited: Not diagnosed or repaired.
Recalls/TSBs owners mention: Manufacturer made aware of failure; no action indicated.
Rear hatch light malfunction and hub clip separation
Rear hatch door light remains illuminated when door is closed. Rear driver side hub clips separate. Burning odor from vents when heating or AC activated.
When: Approximately 4,000 miles.
Symptoms owners cite: Rear hatch door light remains illuminated when closed; Strong burning odor from vents near instrument panel when heating or AC activated; Front end vibration causes steering wheel vibration; Rear driver side hub clips separated
Codes mentioned: OnStar diagnostic case number 109309958
Repairs/costs cited: Not repaired. OnStar connectivity codes cleared; dealer only identified defective module without remedy.
Recalls/TSBs owners mention: Manufacturer determined no remedy was available for the failure. Vehicle not repaired.
Temperature sensor failure affecting remote start
Engine temperature sensor fails, causing remote start feature to stop functioning.
When: Mileage not provided.
Symptoms owners cite: Temperature sensor for engine inoperable; Remote start function does not work
Repairs/costs cited: None provided.
Recalls/TSBs owners mention: None indicated.
Engine block heater recall part unavailability
Recall issued for engine block heater but replacement part unavailable from dealer. Vehicle has been awaiting repair for over 6 months.
When: Taken to dealership over 6 months prior to complaint.
Symptoms owners cite: Engine block heater requires replacement (recall item)
Repairs/costs cited: Replacement part unavailable from dealership for over 6 months.
Recalls/TSBs owners mention: Recall issued but no parts available to complete repair.
Backup camera and warning system failure
Backup camera does not display on screen. Warning chimes and seat vibration alerts do not function when backing up, creating safety hazard and resulting in collision.
When: Mileage not provided.
Symptoms owners cite: Screen went black during backup; Backup camera not displayed; Warning chimes did not sound when backing up; Seat vibration warning did not activate when backing up
Repairs/costs cited: Owner filed insurance claim for dented bumper caused by inability to detect obstacle while backing.
Recalls/TSBs owners mention: None indicated.
Misc. electrical short and audio system issues
Multiple electrical components short out or malfunction, including radio, hands-free calling, mirror lights, and steering wheel audio controls. Issues suggest underlying wiring problems.
When: Mileage not provided.
Symptoms owners cite: Radio does not work; Hands-free calling inoperative; Mirror light shorts and does not work; Steering wheel audio controls do not work; Symptoms suggest short in wiring
Repairs/costs cited: None provided.
Recalls/TSBs owners mention: None indicated.
Infotainment system app and icon malfunction
Infotainment touchscreen goes haywire randomly. System attempts to delete app icons (including camera), delete connected phones, delete radio favorites, and moves app icons without user input. Touchscreen becomes unresponsive during malfunction.
When: Mileage not provided.
Symptoms owners cite: Infotainment system goes haywire randomly; Cannot use touchscreen during malfunction; System attempts to delete camera app icon; System attempts to delete connected phone profiles; System attempts to delete radio favorites; System moves app icons randomly
Repairs/costs cited: None provided.
Recalls/TSBs owners mention: None indicated.
Synthesized from 29 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 4 most recent
The first time while driving at 60 MPH, the vehicle instrument panel warning lights activated and gauges fluctuated followed by acceleration, braking and steering movement. Then the information panel displayed stabilitrak unavailable, collision warning unavailable, lane change alert unavailable and transmission service. The car then started shifting erratically. The 2nd time same situation while…
On Wed., Dec. 6 around 3:15 pm during heavy traffic on FWY [XXX], cars slowed down to a brief complete stop. When I went to start slowly as traffic began to move, engine completely shut down. I could not open windows or my door to get out of vehicle. Immediately called 911 and was transferred to DPS. It took approximately 65 minutes before I had help and was finally towed from the dangerous…
Tl* the contact owns a 2018 GMC terrain. While driving various speeds, the driver's alert warning system failed to operate as intended. The vehicle was taken to an unknown dealer, but the cause of the failure could not be determined. The manufacturer was made aware of the failure and stated that the vehicle was performing as intended. The failure mileage and VIN were not available. *bf lane…
The infotainment system will just randomly start going haywire and when it happens, you cannot use the touchscreen. It will try to randomly delete app icons such as the camera, it will try to delete connected phones, it will try to delete radio favorites and it will move app icons all around. These are just a few examples of things that happen.
Had electrical trouble with your 2018 GMC Terrain?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the electrical problem on the 2018 GMC Terrain?
It's a meaningful issue. 29 complaints have been filed and the failure mode causes operational problems for owners. Repairs average $850.
At what mileage does the electrical typically fail?
Across the 12 complaints that reported odometer mileage, most electrical failures cluster between 15,615 and 52,000 miles, with the median around 30,000. A quarter of owners report trouble before 15,615; a quarter make it past 52,000. Maintenance history matters more than the odometer alone — this is the reported failure window, not a guarantee.
What does it cost to fix?
Independent shops typically charge around $850 for electrical repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to electrical?
No active recalls currently cover electrical issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2018/GMC/Terrain.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.