{
 "id": "4th-gen-4runner",
 "vehicle": "4th Gen 4Runner",
 "platform": "4runner",
 "years": "2003–2009",
 "covers": "2003 to 2009 4Runner with the 4.0L 1GR-FE V6 and the 4.7L 2UZ-FE V8, 2WD and 4WD. Engine specific items are labeled, and some issues apply mainly to early model years.",
 "updated": "2026-10-15",
 "disclaimer": "General guidance from owner experience. Confirm torque specs, fluid capacities and procedures in the factory service manual. Brakes, steering and anything structural: if in doubt, have a qualified shop inspect it before driving.",
 "systems": [
  "Engine",
  "Cooling",
  "Starting & Charging",
  "Fuel & Ignition",
  "Emissions",
  "Drivetrain",
  "Steering & Suspension",
  "Brakes",
  "Transmission",
  "Frame & Body",
  "Body & Electrical"
 ],
 "symptoms": [
  {
   "id": "head-gasket-1gr",
   "title": "V6 losing coolant, cold start misfire or overheating (early 4.0L)",
   "system": "Engine",
   "keywords": [
    "head gasket",
    "1gr-fe",
    "coolant loss",
    "misfire cold start",
    "cylinder 6",
    "p0306",
    "white smoke",
    "bubbles in coolant",
    "gurgling dash",
    "overheating"
   ],
   "summary": "Head gasket leaks are reported on early 1GR-FE V6 trucks, mainly the 2003 to 2005 model years. Typical signs are a slow coolant drop, a cold start misfire and a bubbling expansion tank. Confirm it with a test before spending big money.",
   "checks": [
    {
     "what": "Coolant level over a few days",
     "how": "Check the reservoir cold, mark the level and recheck after several drives. A steady drop with no drips on the ground points to an internal leak.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Chemical block test",
     "how": "Use a combustion leak test kit on the radiator neck. A color change means exhaust gas is getting into the coolant.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Cold start misfire codes",
     "how": "Scan for P0300 or a single cylinder code, often on the rear bank. Misfire on a cold start that clears when warm is a typical pattern.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Pressure test the cooling system",
     "how": "Pressure test with a hand pump and watch for a drop with no external leak. Also look for coolant in the oil on the dipstick.",
     "difficulty": "medium",
     "cost": "$"
    },
    {
     "what": "Repair",
     "how": "The fix is head gasket replacement and checking the heads for flatness. This is a big job, so get a quote before deciding to repair or replace the truck.",
     "difficulty": "hard",
     "cost": "$$$"
    }
   ],
   "guides": [
    {
     "title": "Toyota 1GR-FE 4.0 V6 Engine Guide: Specs, Problems & Reliability",
     "url": "https://toyotadata.com/guides/toyota-1gr-fe-engine-guide-4-0-v6-specs-problems-reliability/"
    }
   ],
   "url": "https://toyotadata.com/troubleshooter/4th-gen-4runner/#head-gasket-1gr"
  },
  {
   "id": "frame-rust",
   "title": "Frame rust or rusted suspension mounts",
   "system": "Frame & Body",
   "keywords": [
    "frame rust",
    "rusty frame",
    "rotted frame",
    "control arm mount",
    "spare tire carrier",
    "rust holes",
    "frame inspection",
    "rust perforation",
    "salt rust",
    "undercoating"
   ],
   "summary": "Rust on these trucks is a known concern in salt states, with reports of corrosion near the rear and at suspension link mounts. Check it before you buy and every year if you live where roads are salted.",
   "safety": "Rust that weakens frame rails or suspension mounts can fail suddenly. Have anything soft or perforated inspected by a shop before towing or heavy use.",
   "checks": [
    {
     "what": "Tap the rails",
     "how": "Tap with a hammer along both frame rails, around the spare tire carrier and near the rear cross members. A solid ring is good. A dull thud or flaking scale means more inspection.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Suspension mounting points",
     "how": "Look at the front lower control arm pockets and rear trailing arm mounts. Rust here can loosen the suspension.",
     "difficulty": "medium",
     "cost": "$"
    },
    {
     "what": "Inside the rails",
     "how": "Use a flashlight and a small mirror or borescope through the openings in the frame. Rust scale inside is a warning even if the outside looks fine.",
     "difficulty": "medium",
     "cost": "$"
    },
    {
     "what": "Spare tire and rear bumper area",
     "how": "Drop the spare and look at the carrier and the rail ends behind it. This area often shows damage first.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Protection and repair",
     "how": "Wash the underside after winter and apply a wax or oil based rust inhibitor to the inside and outside of the rails. Welded repairs of structural sections should be done by a shop.",
     "difficulty": "hard",
     "cost": "$$$"
    }
   ],
   "guides": [],
   "url": "https://toyotadata.com/troubleshooter/4th-gen-4runner/#frame-rust"
  },
  {
   "id": "front-end-clunk",
   "title": "Clunk, knock or wandering from the front suspension",
   "system": "Steering & Suspension",
   "keywords": [
    "clunk",
    "knock over bumps",
    "ball joint",
    "control arm",
    "steering wander",
    "x-reas",
    "sway bar link",
    "creaking",
    "front end noise",
    "play in wheel"
   ],
   "summary": "Start with sway bar links and bushings, then check the ball joints and control arm bushings. If your truck has X-REAS, leaks from those shocks can also cause noise and a rough ride.",
   "safety": "Worn ball joints and steering parts can fail. Do not drive on a joint with obvious play.",
   "checks": [
    {
     "what": "Sway bar end links and bushings",
     "how": "Grab the end links and shake them with the truck on the ground, then look for worn bushings. This is the cheapest cause of a clunk over bumps.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Ball joints",
     "how": "Lift the front end on stands and rock the wheel at 12 and 6. Pry between the lower arm and knuckle and look for movement or torn boots.",
     "difficulty": "medium",
     "cost": "$"
    },
    {
     "what": "Control arm bushings",
     "how": "Look for cracked rubber and arm movement at the pivot bolts. Torque the bolts at ride height after any replacement.",
     "difficulty": "medium",
     "cost": "$$"
    },
    {
     "what": "Shocks and X-REAS",
     "how": "Look for fluid on the shock bodies. On trucks with X-REAS, check the cross linked shocks and lines for leaks.",
     "difficulty": "medium",
     "cost": "$$"
    },
    {
     "what": "Steering rack and tie rod ends",
     "how": "Check for leaks at the rack boots and play at the tie rod ends. A weeping rack is common on aging trucks.",
     "difficulty": "medium",
     "cost": "$$"
    }
   ],
   "guides": [],
   "url": "https://toyotadata.com/troubleshooter/4th-gen-4runner/#front-end-clunk"
  },
  {
   "id": "sticky-cracked-dash",
   "title": "Sticky, melting or cracked dashboard",
   "system": "Body & Electrical",
   "keywords": [
    "sticky dash",
    "melting dashboard",
    "cracked dash",
    "dash cover",
    "sticky dashboard",
    "dash replacement",
    "glare",
    "warranty enhancement",
    "dashboard damage",
    "shiny dash"
   ],
   "summary": "Heat and humidity damage to the dash surface has been reported on 2003 to 2005 trucks, and Toyota ran a warranty enhancement program for certain ones. Ask a Toyota dealer if your VIN is covered, as time limits may have passed.",
   "checks": [
    {
     "what": "Check coverage by VIN",
     "how": "Call a Toyota dealer with your VIN to see if the warranty enhancement program for dashboard damage still applies. Do not assume it is expired.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Clean the surface",
     "how": "A sticky film can sometimes be removed with isopropyl alcohol and a microfiber cloth. Avoid greasy dash dressings that make it worse.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Dash cover",
     "how": "A fitted dash cover hides damage and cuts windshield glare. It does not stop the problem from progressing.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Replacement or re-skin",
     "how": "A used dash from a clean truck or a professional re-skin are options. A full replacement is a lot of labor.",
     "difficulty": "hard",
     "cost": "$$$"
    }
   ],
   "guides": [],
   "url": "https://toyotadata.com/troubleshooter/4th-gen-4runner/#sticky-cracked-dash"
  },
  {
   "id": "timing-belt-2uz",
   "title": "V8 timing belt service: when is it due?",
   "system": "Engine",
   "keywords": [
    "2uz-fe",
    "timing belt",
    "v8 timing belt",
    "belt interval",
    "water pump",
    "90000 miles",
    "belt replacement",
    "timing belt due",
    "tensioner"
   ],
   "summary": "The 4.7L 2UZ-FE uses a timing belt and Toyota's schedule calls for replacement around 90,000 miles. The 4.0L 1GR-FE V6 uses a timing chain, so there is no belt service on it.",
   "checks": [
    {
     "what": "Confirm the engine",
     "how": "Check the VIN or the badges. The V6 uses a chain and does not need a belt. Only the V8 does.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Look for service records",
     "how": "Find an invoice that lists belt, tensioner, idlers and water pump. If no proof, treat the truck as overdue and budget for it.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Replace as a kit",
     "how": "Do the belt, water pump, tensioner and idler pulleys together, plus the front seals if they weep. The labor overlaps so doing it all at once saves money.",
     "difficulty": "hard",
     "cost": "$$"
    },
    {
     "what": "Check for leaks at the front",
     "how": "Oil or coolant around the timing cover area is a sign to deal with it at the same time. Oil on the belt shortens its life.",
     "difficulty": "medium",
     "cost": "$"
    }
   ],
   "guides": [
    {
     "title": "Toyota 2UZ-FE 4.7 V8: Specs, Reliability & High Mileage Guide",
     "url": "https://toyotadata.com/guides/the-legendary-toyota-2uz-fe-v8-engine-a-testament-to-unmatched-reliability/"
    }
   ],
   "url": "https://toyotadata.com/troubleshooter/4th-gen-4runner/#timing-belt-2uz"
  },
  {
   "id": "exhaust-manifold-tick",
   "title": "Ticking or diesel-like noise on cold start",
   "system": "Engine",
   "keywords": [
    "ticking",
    "tick on cold start",
    "exhaust manifold crack",
    "manifold leak",
    "exhaust leak",
    "diesel sound",
    "cold start noise",
    "2uz-fe",
    "manifold gasket",
    "loose heat shield"
   ],
   "summary": "On the V8 the cast iron exhaust manifolds can crack near the flanges, causing a loud tick on cold start that fades as the metal expands. Rule out a loose heat shield or a gasket leak first.",
   "checks": [
    {
     "what": "Heat shields",
     "how": "Tap the heat shields and look for loose bolts or rattles. A loose shield makes noises that mimic an exhaust leak.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Listen cold",
     "how": "Start the engine cold and listen at each side. A tick that quiets as it warms up points to a manifold crack or leaking gasket.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Look for soot marks",
     "how": "Check around the manifold flanges and studs for black soot trails. Broken studs are common.",
     "difficulty": "medium",
     "cost": "$"
    },
    {
     "what": "Valve train noise",
     "how": "If the tick stays when warm, check oil level and listen for lifter or cam noise. A running tick that follows RPM is not a manifold leak.",
     "difficulty": "medium",
     "cost": "$"
    },
    {
     "what": "Replace manifold or gasket",
     "how": "Replace the cracked manifold and gaskets and renew any broken studs. Expect seized hardware on older trucks.",
     "difficulty": "hard",
     "cost": "$$$"
    }
   ],
   "guides": [
    {
     "title": "Toyota 2UZ-FE 4.7 V8: Specs, Reliability & High Mileage Guide",
     "url": "https://toyotadata.com/guides/the-legendary-toyota-2uz-fe-v8-engine-a-testament-to-unmatched-reliability/"
    }
   ],
   "url": "https://toyotadata.com/troubleshooter/4th-gen-4runner/#exhaust-manifold-tick"
  },
  {
   "id": "overheating",
   "title": "Engine overheating or temperature gauge climbing",
   "system": "Cooling",
   "keywords": [
    "overheating",
    "overheat",
    "temp gauge high",
    "coolant loss",
    "radiator",
    "thermostat",
    "water pump",
    "fan clutch",
    "steam",
    "heater blows cold"
   ],
   "summary": "Check the basics first: coolant level, radiator, cap and fan. On early V6 trucks also keep the head gasket in mind, and on the V8 remember the water pump is belt driven.",
   "safety": "Never open the radiator cap or coolant reservoir on a hot engine. Let it cool fully first.",
   "checks": [
    {
     "what": "Coolant level and condition",
     "how": "Check the radiator and reservoir cold. Low coolant means find the leak. Oily or rusty coolant points to deeper problems.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Radiator, hoses and cap",
     "how": "Look for crusty residue at the radiator seams and hoses, and squeeze hoses when cool. Replace a weak cap.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Fan operation",
     "how": "Check the fan clutch by spinning it cold for resistance. A clutch that doesn't lock when hot lets the engine overheat in traffic.",
     "difficulty": "easy",
     "cost": "$$"
    },
    {
     "what": "Water pump and thermostat",
     "how": "Look for weeping at the pump weep hole or a pump that wobbles. A stuck thermostat is a cheap part to replace.",
     "difficulty": "medium",
     "cost": "$$"
    },
    {
     "what": "Head gasket test",
     "how": "If coolant keeps disappearing with no external leak, run a chemical block test. This is a particular concern on 2003 to 2005 V6 trucks.",
     "difficulty": "easy",
     "cost": "$"
    }
   ],
   "guides": [],
   "url": "https://toyotadata.com/troubleshooter/4th-gen-4runner/#overheating"
  },
  {
   "id": "milky-transmission-fluid",
   "title": "Pink or milky transmission fluid, coolant in the transmission",
   "system": "Transmission",
   "keywords": [
    "milky transmission fluid",
    "pink fluid",
    "strawberry milkshake",
    "coolant in transmission",
    "transmission cooler",
    "radiator cooler leak",
    "atf contaminated",
    "slipping",
    "transmission fluid"
   ],
   "summary": "The transmission cooler inside the radiator can leak and mix coolant with the fluid. Catch it early because coolant in the transmission damages the clutches.",
   "safety": "Do not keep driving with coolant mixed into the transmission fluid. Tow it if the fluid is pink or foamy.",
   "checks": [
    {
     "what": "Dipstick and coolant check",
     "how": "Check the transmission fluid color and smell. Also look at the radiator coolant for an oily film.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Pressure test the radiator cooler",
     "how": "A shop can test the cooler passages. Many owners replace the radiator whenever this is suspected.",
     "difficulty": "medium",
     "cost": "$$"
    },
    {
     "what": "Replace radiator and lines",
     "how": "Replace the radiator and inspect the cooler lines for cracked hoses. Flush the cooler circuit to get the old fluid out.",
     "difficulty": "medium",
     "cost": "$$"
    },
    {
     "what": "Transmission service",
     "how": "After the leak is fixed, do a full fluid exchange and watch shift quality. Slipping or a burnt smell afterward means a rebuild may be needed.",
     "difficulty": "hard",
     "cost": "$$$"
    }
   ],
   "guides": [],
   "url": "https://toyotadata.com/troubleshooter/4th-gen-4runner/#milky-transmission-fluid"
  },
  {
   "id": "no-crank",
   "title": "Turn the key: click or nothing, engine won't crank",
   "system": "Starting & Charging",
   "keywords": [
    "no crank",
    "click",
    "won't start",
    "wont start",
    "starter",
    "dead battery",
    "neutral safety switch",
    "push button",
    "key won't turn",
    "clicking noise"
   ],
   "summary": "Rule out the battery, terminals and grounds first, because those are free or cheap. Then move to the starter, the neutral safety switch and the key or immobilizer system.",
   "checks": [
    {
     "what": "Battery voltage",
     "how": "Resting voltage should be about 12.4 V or more. Under 12 V, charge and load-test the battery before chasing anything else.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Terminals and grounds",
     "how": "Clean and tighten both battery terminals, the engine ground and the starter cable. Corrosion can mimic a dead battery.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Shift to Neutral",
     "how": "Try starting in Neutral. A worn neutral start switch can block cranking in Park.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Security light",
     "how": "Watch the security indicator when you turn the key. A flashing light that stays on can mean the immobilizer is not recognizing the key.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Starter",
     "how": "A single click with a good battery points to the starter or its solenoid. Bench test it or swap it.",
     "difficulty": "medium",
     "cost": "$$"
    }
   ],
   "guides": [],
   "url": "https://toyotadata.com/troubleshooter/4th-gen-4runner/#no-crank"
  },
  {
   "id": "secondary-air-limp",
   "title": "Check engine light with secondary air code, or truck in limp mode",
   "system": "Emissions",
   "keywords": [
    "secondary air injection",
    "air pump",
    "p0410",
    "limp mode",
    "check engine",
    "air injection pump",
    "air switching valve",
    "air pump failed",
    "emissions",
    "reduced power"
   ],
   "summary": "On the V8, moisture can kill the secondary air injection pump, which sets codes and can trigger reduced power. Confirm the codes, then check the pump, valves and wiring before ordering parts.",
   "checks": [
    {
     "what": "Read the codes",
     "how": "Scan for P0410 or other air injection codes. Write down the freeze frame and clear them to see if they come back.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Pump and relay power",
     "how": "Check the fuse and relay and confirm the pump gets power when commanded at cold start. A silent pump with power is bad.",
     "difficulty": "medium",
     "cost": "$"
    },
    {
     "what": "Air switching valves and hoses",
     "how": "Look at the valves and the pipes for water, corrosion and cracks. Moisture in the lines is a common failure path.",
     "difficulty": "medium",
     "cost": "$$"
    },
    {
     "what": "Replace pump or valve",
     "how": "Replace the failed part with a quality unit. Bypass kits exist, but they can affect emissions testing where that applies.",
     "difficulty": "medium",
     "cost": "$$"
    }
   ],
   "guides": [
    {
     "title": "Toyota 2UZ-FE 4.7 V8: Specs, Reliability & High Mileage Guide",
     "url": "https://toyotadata.com/guides/the-legendary-toyota-2uz-fe-v8-engine-a-testament-to-unmatched-reliability/"
    }
   ],
   "url": "https://toyotadata.com/troubleshooter/4th-gen-4runner/#secondary-air-limp"
  },
  {
   "id": "check-engine-codes",
   "title": "Check engine light with a lean, misfire or catalyst code",
   "system": "Fuel & Ignition",
   "keywords": [
    "check engine light",
    "cel",
    "p0171",
    "p0174",
    "p0300",
    "p0420",
    "p0430",
    "lean code",
    "misfire",
    "catalytic converter"
   ],
   "summary": "Read the code before buying parts. Lean codes usually trace to a dirty MAF sensor or a vacuum leak, and catalyst codes need exhaust leak and sensor checks first.",
   "checks": [
    {
     "what": "Read codes and freeze frame",
     "how": "Use a scan tool and note the code with engine temperature and speed. Clear it and see how fast it returns.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "MAF sensor and air intake",
     "how": "Clean the MAF with MAF cleaner only and check the intake tube clamps for leaks. A loose boot causes lean codes.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Vacuum and PCV lines",
     "how": "Inspect hoses for cracks and check the PCV valve. A leak near the intake can set P0171 or P0174.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Plugs and coils",
     "how": "A misfire code needs plugs and coil checks. Swap a suspect coil to another cylinder and see if the code follows.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Catalyst codes",
     "how": "Check for exhaust leaks before the downstream sensor and test the oxygen sensors before condemning the converter.",
     "difficulty": "medium",
     "cost": "$$"
    }
   ],
   "guides": [],
   "url": "https://toyotadata.com/troubleshooter/4th-gen-4runner/#check-engine-codes"
  },
  {
   "id": "rough-idle-misfire",
   "title": "Rough idle, misfire or hesitation",
   "system": "Fuel & Ignition",
   "keywords": [
    "rough idle",
    "misfire",
    "hesitation",
    "stumble",
    "shaking at idle",
    "p0300",
    "coil pack",
    "spark plug",
    "stalling",
    "poor acceleration"
   ],
   "summary": "Spark plugs, coils and a dirty throttle body are the usual causes. On early V6 trucks a cold start misfire can also be an early sign of a head gasket problem.",
   "checks": [
    {
     "what": "Spark plugs",
     "how": "Pull the plugs and look at the gap and wear. Replace them with the correct type and gap as a full set.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Ignition coils",
     "how": "Swap suspect coils between cylinders and see if the misfire moves. Replace any failing coil.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Throttle body",
     "how": "Clean the throttle plate and bore with throttle body cleaner. Carbon buildup causes a rough or hunting idle.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Fuel injectors",
     "how": "Listen to each injector with a stethoscope for a steady click. A clogged injector can cause a misfire on one cylinder.",
     "difficulty": "medium",
     "cost": "$"
    },
    {
     "what": "Misfire only when cold",
     "how": "If a single cylinder misfires on cold start and clears warm, check for coolant loss and run a block test, especially on 2003 to 2005 V6 trucks.",
     "difficulty": "easy",
     "cost": "$"
    }
   ],
   "guides": [],
   "url": "https://toyotadata.com/troubleshooter/4th-gen-4runner/#rough-idle-misfire"
  },
  {
   "id": "brake-issues",
   "title": "Brakes pull, grind, pulsate, or ABS and brake warning lights on",
   "system": "Brakes",
   "keywords": [
    "brakes pull",
    "brake pulsation",
    "grinding",
    "sticking caliper",
    "abs light",
    "brake light on",
    "vsc light",
    "trac light",
    "hard pedal",
    "pump noise"
   ],
   "summary": "Front calipers that stick from salt and heat are a common cause of pulling and uneven pad wear. If the pedal is hard or you hear a chirp and warning lights, the ABS hydraulic unit needs a look.",
   "safety": "Brakes are a safety system. If the pedal is soft, very hard, or goes to the floor, do not drive the truck.",
   "checks": [
    {
     "what": "Pads and rotors",
     "how": "Pull the wheels and check pad thickness and the wear pattern. Uneven wear between pads on one caliper points to a sticking piston or slides.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Caliper slides and pistons",
     "how": "Clean and grease the slide pins with brake grease and check that the pistons retract freely. Replace a caliper that won't move.",
     "difficulty": "medium",
     "cost": "$$"
    },
    {
     "what": "Brake fluid",
     "how": "Check the level and color. Old fluid is dark and should be flushed.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "ABS pump or accumulator",
     "how": "A hard pedal, a loud pump chirp or ABS and brake lights together point to the ABS hydraulic unit or accumulator. Have it scanned and inspected by a shop.",
     "difficulty": "hard",
     "cost": "$$$"
    },
    {
     "what": "Wheel speed sensors",
     "how": "A dirty or damaged speed sensor sets ABS, VSC and TRAC lights. Check the sensor and tone ring and read the codes.",
     "difficulty": "medium",
     "cost": "$$"
    }
   ],
   "guides": [],
   "url": "https://toyotadata.com/troubleshooter/4th-gen-4runner/#brake-issues"
  },
  {
   "id": "4wd-wont-engage",
   "title": "4WD won't engage, front axle stuck or binding",
   "system": "Drivetrain",
   "keywords": [
    "4wd not working",
    "4wd won't engage",
    "four wheel drive",
    "4wd light flashing",
    "4wd actuator",
    "transfer case",
    "4 low",
    "front axle",
    "center diff",
    "4wd switch"
   ],
   "summary": "Actuators on the front axle and transfer case can stick or fail from rust and age. Check fuses and codes first, then the actuators.",
   "checks": [
    {
     "what": "Indicator lights",
     "how": "Watch the 4WD lights when you move the switch. A flashing light means the system did not complete the shift and may have a stored code.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Fuses and wiring",
     "how": "Check the fuses and the actuator connectors for corrosion. Water in a connector can stop the shift.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Front axle actuator",
     "how": "Inspect for a stuck shaft or a failed actuator. Cleaning and lubing may free it, otherwise replace it.",
     "difficulty": "medium",
     "cost": "$$"
    },
    {
     "what": "Transfer case actuator and fluid",
     "how": "Check the fluid level and condition, and listen for the motor when you change modes. A dead motor needs replacing.",
     "difficulty": "medium",
     "cost": "$$"
    },
    {
     "what": "Test on loose ground",
     "how": "Binding on dry pavement is normal for part time systems. Test on gravel or dirt before assuming a fault.",
     "difficulty": "easy",
     "cost": "$"
    }
   ],
   "guides": [],
   "url": "https://toyotadata.com/troubleshooter/4th-gen-4runner/#4wd-wont-engage"
  },
  {
   "id": "driveline-clunk",
   "title": "Driveshaft clunk, vibration or wheel bearing noise",
   "system": "Drivetrain",
   "keywords": [
    "driveshaft clunk",
    "u-joint",
    "vibration under load",
    "wheel bearing",
    "growl",
    "diff noise",
    "pinion seal",
    "cv axle",
    "clunk when shifting",
    "rumble"
   ],
   "summary": "Worn u-joints and a dry slip yoke are cheap suspects for a clunk when shifting. A growl that changes with speed or turning usually points to wheel bearings.",
   "checks": [
    {
     "what": "U-joints and slip yoke",
     "how": "Twist the driveshaft by hand and look for play at the joints. Grease the slip yoke if there is a fitting and replace any rusty joint.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Wheel bearings",
     "how": "Lift the truck and rock each wheel, then spin it by hand and listen. A growl or roughness points to the bearing.",
     "difficulty": "medium",
     "cost": "$$"
    },
    {
     "what": "Front CV axles on 4WD",
     "how": "Clicking on turns with the wheel cranked over points to a worn CV joint. Look for torn boots and flung grease.",
     "difficulty": "medium",
     "cost": "$$"
    },
    {
     "what": "Differential fluid and seals",
     "how": "Check fluid in the front and rear differentials and look for pinion seal leaks. Low or burnt fluid explains a whine.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Tire balance and wear",
     "how": "A vibration at speed that matches wheel speed is often a balance or tire problem. Check it before the driveline.",
     "difficulty": "easy",
     "cost": "$"
    }
   ],
   "guides": [
    {
     "title": "Toyota Regear Chart: Tire Size vs Gear Ratio vs RPM",
     "url": "https://toyotadata.com/guides/toyota-regear-chart-tire-size-gear-ratio-rpm/"
    }
   ],
   "url": "https://toyotadata.com/troubleshooter/4th-gen-4runner/#driveline-clunk"
  },
  {
   "id": "ac-blend-door",
   "title": "Clicking behind the dash, A/C or heater not changing temperature",
   "system": "Body & Electrical",
   "keywords": [
    "clicking behind dash",
    "blend door actuator",
    "ac not cold",
    "heater not working",
    "temperature won't change",
    "hvac",
    "air conditioning",
    "ac compressor",
    "blower motor",
    "vent switching"
   ],
   "summary": "A failing HVAC actuator will click and leave you stuck on hot or cold. Check the refrigerant side of the A/C separately.",
   "checks": [
    {
     "what": "Listen for clicking",
     "how": "With the key on, change the temperature and mode settings and listen behind the dash. Repeated clicking points to a stripped actuator gear.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Cabin air filter and blower",
     "how": "Replace a clogged filter and check blower speeds. Weak airflow is often just the filter.",
     "difficulty": "easy",
     "cost": "$"
    },
    {
     "what": "Compressor clutch",
     "how": "With the A/C on, check that the compressor clutch engages. If it doesn't, check the fuse, relay and refrigerant pressure.",
     "difficulty": "medium",
     "cost": "$"
    },
    {
     "what": "Refrigerant level",
     "how": "Low refrigerant means there is a leak. Have it leak tested and not just topped off.",
     "difficulty": "medium",
     "cost": "$$"
    },
    {
     "what": "Replace the actuator",
     "how": "Actuators are replaceable but access can be tight. Replace the one that is clicking.",
     "difficulty": "hard",
     "cost": "$$"
    }
   ],
   "guides": [],
   "url": "https://toyotadata.com/troubleshooter/4th-gen-4runner/#ac-blend-door"
  }
 ],
 "source": "https://toyotadata.com/troubleshooter/4th-gen-4runner/",
 "usage": "Checks are ordered: run them top to bottom. difficulty is easy|medium|hard, cost is $ (under ~$50) to $$$ (shop-level job)."
}