This service bulletin provides information on some vehicles that may rock or move slightly forward or rearward while in Park at start up after cold soak. This condition may be accompanied by a clunk noise. This is a slight movement that is more often seen visually, rather than felt, when viewed from the outside and using the auto-start feature, if equipped.
full bulletin at NHTSA ↗2008 Chevrolet Trailblazer powertrain problems
severe 10 complaints filed with NHTSA · avg repair $2,500 · see powertrain across all vehicles →
Failure mileage
Complaints
10
Recalls
0
Avg fix
$2,500
1crash
1fire
1injury
When does it fail?
Of the 10 powertrain complaints filed for the 2008 Chevrolet Trailblazer, here's the actual mileage breakdown — failures cluster heaviest at 150,000+ 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
No new NHTSA powertrain complaint has been filed on this vehicle in over 5 years — the issue may be aging out of the active population.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering powertrain 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.
GM is receiving damaged (cracked or broken) transmission cores returned to the reman facilities. The damage is being caused either in the removal process by the technician, or inadequate packaging or shipping. This bulletin advises the dealers to be more careful not to damage the transmissions during removal and to package the core properly for return.
full bulletin at NHTSA ↗This bulletin provides information on the harmful effects of water or ethylene glycol in transmission fluid.
full bulletin at NHTSA ↗This service bulletin provides technicians with information to help identify the differences between what is considered a fluid leak, and what is considered fluid seepage.
full bulletin at NHTSA ↗This Warranty Admin service bulletin provides guidelines for Dealers Not Required and for Dealers Required to Contact the PQC for engine or transmission assembly replacement and explains the PQC process, GWM Transaction submission, vehicle service record retention and proper handling of assembly returns for Canadian Dealers only.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
Owners report powertrain failures that range from warning lights that won't go away to complete loss of drive. The transmission can refuse to shift into higher gears, then lurch downward violently, before stopping completely—with the engine revving but the vehicle not moving. One owner had the front differential fail due to stripped splines and gears, with a private shop diagnosis pointing to inadequate oil lubrication of the output shaft as a design flaw rather than a maintenance issue.
Electrical faults are widespread: StabiliTrak lights come on repeatedly even after dealer resets, traction control warnings appear constantly regardless of weather, and cryptic powertrain/electrical warning lights cycle on and off without pattern. Some owners smell burning or smoke; most don't. Multiple dealerships have been unable to identify the root cause.
Other reported failures include throttle position sensor faults (code P2135), rough idle on startup, unexpected shifts from 2WD to 4WD at highway speed, and a vehicle that rolled backward unprompted while parked. Owners have made repeated dealer visits—sometimes seven or more—with permanent fixes rare. One owner's transferred case was finally replaced after two years of complaints. Warranty expiration leaves owners paying out of pocket for diagnostics with no guarantee of coverage.
Same Chevrolet Trailblazer powertrain reports on nearby years: 2005 · 2006 · 2007
Failure modes owners describe
Automatic transmission shift failure and complete loss of drive
Transmission fails to shift into 4th/overdrive, drops to 3rd gear, lurches harshly on downshift, then loses all forward motion. Engine revs but vehicle does not move.
When: 436-1,236 miles; early in vehicle life
Symptoms owners cite: Refuses to shift into 4th gear or overdrive; Downshifts abruptly into 3rd at highway speed; Harsh lurching on downshift; Engine revs when throttle pressed but no forward motion; Complete loss of drive ability; Clunking noise from transmission
Repairs/costs cited: Complete transmission failure requiring vehicle exchange (rental scenario); repair cost not specified
Front differential power output shaft spline stripping
Front differential components become dry and brittle due to inadequate engine oil lubrication reaching the output shaft and spline. Spline strips, gears strip, and drivetrain fails completely. Owner alleges this is a design flaw where components are not properly encased or lubricated.
When: No mileage stated; after normal driving
Symptoms owners cite: Loud bang noise when accelerating; Vehicle fails to engage when attempting to accelerate; Engine whines under acceleration but vehicle does not move; Vehicle rolls backward without emergency brake applied
Repairs/costs cited: Private shop diagnosis: front differential damaged, power output shaft and spline stripped. Owner states this is design flaw, not maintenance issue.
Throttle/pedal position sensor correlation fault (P2135)
Engine stalls during turns with malfunction indicator lamp illuminating. Diagnostic code P2135 reads throttle/pedal position sensor/switch A/B voltage correlation. Service bulletin 340852 exists for this model year per owner, but dealer claims vehicle not covered.
When: During normal driving; timing not specified
Symptoms owners cite: Engine stalls during turns; Malfunction indicator lamp illuminates; Loss of engine power
Codes mentioned: P2135
Repairs/costs cited: No repair completed; dealer refused coverage citing warranty expiration
Recalls/TSBs owners mention: NHTSA Service Bulletin 340852 exists for this defect on 2008 model year, but dealer and GM denied coverage to owner
StabiliTrak system malfunction and transfer case failure
StabiliTrak service light illuminates repeatedly during wet/icy conditions when traction control does not engage properly. Vehicle shifts from 2WD to 4WD low at highway speed unprompted. Dealer visits did not resolve the issue until transfer case replacement.
When: Starting around 15,000 miles; repeated failures over 2-year period through 70,000 miles
Symptoms owners cite: StabiliTrak service light comes on during inclement weather; StabiliTrak does not function on ice patches; Unwanted shift from 2WD to 4WD low at highway speed; Repeated warning light resets with no permanent fix
Repairs/costs cited: Multiple dealer resets failed to solve problem; transfer case replacement finally resolved issue after seven service visits over two years
Intermittent powertrain/electrical warning lights with unidentified root cause
Dashboard warning lights indicating powertrain and electrical issues come on and off without pattern. Some instances accompanied by smoke or burning smell, others without. Multiple dealers across states unable to replicate or identify the problem. Dealer replaced stereo based on GMEO recommendation despite lights indicating powertrain/electrical, not audio.
When: Recurring throughout ownership; no specific timing
Symptoms owners cite: Dash warning lights for powertrain/electrical come on repeatedly; Lights cycle on and off without pattern; Intermittent smell of smoke or burning; Warning lights appear during 4WD use; Problem occurs at multiple locations with different dealers
Repairs/costs cited: Stereo replacement by GMEO recommendation; fuse related to 4WD identified as possible issue but not permanently fixed; replaced stereo failed 2 months later
Recalls/TSBs owners mention: GMEO replaced stereo; GMEO and Washington dealership identified fuse issue related to 4WD; case closed as resolved by GMEO despite ongoing symptoms
Traction control light malfunction
Traction control warning lights illuminate repeatedly without cause, in all weather and driving conditions. Lights come on immediately when engine is started. Dealer unable to diagnose or repair after multiple visits over two-year period.
When: Since purchase in September 2009; persistent through vehicle life
Symptoms owners cite: Traction control lights come on for no apparent reason; Occurs in hot, cold, dry, and wet conditions; Lights illuminate as soon as engine starts; No identifiable trigger
Repairs/costs cited: No repair possible; dealer states they cannot identify cause after multiple visits
Vehicle rolling backward when parked
Vehicle independently begins rolling backward while parked with engine off, even though emergency brake was not released. Vehicle rolled into street without operator control.
When: At 26,000 miles
Symptoms owners cite: Vehicle rolls backward with engine off; No brake application by operator; Continued rolling into street
Repairs/costs cited: No diagnosis or repair performed; owner did not take vehicle to dealer
Rough idle and throttle position sensor fault
Vehicle has difficulty maintaining idle after starting and does not want to move. Owner identifies throttle position sensor as cause of rough idle condition.
When: During normal operation
Symptoms owners cite: Rough idle when first starting; Engine does not want to keep running; Vehicle does not want to move from standstill
Repairs/costs cited: Throttle position sensor replacement cost $300
Front-end shaking at highway speed with transmission bogging
Front end shakes during highway driving. Transmission bogs down during normal speed operation.
When: During highway driving
Symptoms owners cite: Front-end shaking at highway speed; Transmission bogs down at normal speed
Synthesized from 10 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 2 most recent
Yes I was driving on the 65 miles an hour in the passenger lane are carpool lane all the sudden for no reason both curtain airbags just deployed I had my head right next to knock me out cold I didn't proceed over and hit the wall 21 times just skip down in when I came to I thought I was I thought it and other vehicles likely that was not the case did cause some testa injury hurt might pull my car…
My 2008 trailblazer is having a rough idling issue.. When I first start my vehicle it does not want to keep running. It doesnt want to move either. It is the throttle position sensor and it cost 300.00 to buy the part
Had powertrain trouble with your 2008 Chevrolet Trailblazer?
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 powertrain problem on the 2008 Chevrolet Trailblazer?
It's a meaningful issue. 10 complaints have been filed and the failure mode causes operational problems for owners. Repairs average $2,500.
At what mileage does the powertrain typically fail?
Across the 9 complaints that reported odometer mileage, most powertrain failures cluster between 26,000 and 92,000 miles, with the median around 62,916. A quarter of owners report trouble before 26,000; a quarter make it past 92,000. 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 $2,500 for powertrain 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 powertrain?
No active recalls currently cover powertrain 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/2008/Chevrolet/Trailblazer.
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.