2006 CHEVROLET TRAILBLAZER

Typical onset: 100,000-150,000 mi

Symptoms: Sudden knocking or hammering from engine bay, Metal shavings in oil, may show on oil filter inspection, Loss of oil pressure, oil pressure warning light, Complete engine seizure if driven after symptoms start

Fix: Main and rod bearings fail catastrophically, often taking crankshaft and block with them. Rebuild requires machine work (crank grinding, align hone) if caught early, but most need complete engine replacement or short block. 18-24 labor hours for R&R plus machine shop time.

Estimated cost: $3,500-6,500

Typical onset: 120,000-180,000 mi

Symptoms: Harsh or delayed 1-2 shift, slipping in 2nd or 3rd gear, Transmission fluid leaking from radiator cooler lines or at transmission oil cooler, Check Engine light with P0751 (shift solenoid) or P0730 (incorrect gear ratio), Shuddering during light throttle acceleration

Fix: These transmissions eat 3-4 clutches and suffer valve body issues. Cooler lines rot at frame contact points causing leaks. Proper rebuild with updated components runs 12-16 hours; cooler line replacement adds 2-3 hours. Many shops recommend replacement over rebuild on high-mileage units.

Estimated cost: $2,200-3,800

Typical onset: 80,000-140,000 mi

Symptoms: Service 4WD message on dash, 4WD system will not engage or disengage, Grinding or clicking from front axle area when attempting 4WD engagement, 4WD indicator light flashing

Fix: The thermal actuator on front axle and encoder motor on transfer case both fail regularly. Actuator replacement is 2-3 hours, encoder motor is 1.5-2 hours. Often both fail within 20k miles of each other. Dorman replacements available but OEM AC Delco parts last longer.

Estimated cost: $450-850

Symptoms: Blower fan only works on high speed (resistor failure), No blower function at all (control module failure), Intermittent blower operation or cycling on/off

Fix: The resistor module behind glove box fails from heat cycling, followed eventually by the control module itself. Resistor is 0.5 hour job, control module is 1.5-2 hours as dash needs partial disassembly. Common failure on all GM trucks this era.

Estimated cost: $180-450

Typical onset: 90,000-150,000 mi

Symptoms: Whining noise when turning, especially when cold, Power steering fluid leaking from pump or high-pressure hose, Hard steering or complete loss of power assist, Visible fluid spray on engine bay components

Fix: Pump seals leak and pressure hoses crack at crimp points (NHTSA recall addressed some years but not all). Pump replacement is 2-3 hours, high-pressure hose adds 1-2 hours due to tight routing. Rack leaks are less common but do occur at 150k+.

Estimated cost: $450-900

Typical onset: 100,000-160,000 mi

Symptoms: No-start condition with whirring or silent fuel pump, Erratic or inaccurate fuel gauge reading, Engine stalling or hesitation during acceleration, Check Engine light with P0230 (fuel pump circuit) or low fuel pressure codes

Fix: In-tank pump fails from age and contamination. Tank must be dropped for access, 3-4 hours labor. Recommend replacing entire module assembly including sender to avoid repeat visits. Common enough that many owners carry a spare.

Estimated cost: $650-1,100

Symptoms: Battery drain from Onstar module staying awake, Compass/temperature display in overhead console dead or intermittent, Dome lights not working or stuck on, Random electrical accessories losing power

Fix: Onstar modules develop parasitic draw (50-150mA) killing batteries overnight. Overhead console circuit boards crack from heat. Onstar module disconnect is 0.5 hour, overhead console replacement is 1 hour. Many owners simply delete Onstar to solve drain issue.

Estimated cost: $150-400