3rd Gen 4Runner Troubleshooter

Front lower ball joints are the famous wear item on this generation, and certain 2001 and 2002 trucks were part of a Toyota recall for scratched lower ball joint surfaces. Check the ball joints first, then the rest of the front end.

1. Lower ball joint play
   Jack the front end, support it on stands, and grab the tire at 6 and 12 o'clock. Rock it hard in and out while a helper watches the joint, or pry between the lower arm and knuckle. Visible movement or a torn boot means replace it.
   medium$
2. Recall status on 2001 to 2002 trucks
   Run the VIN through NHTSA's recall lookup or ask a Toyota dealer if the lower ball joint campaign was done. If it was done, the replacement joints are an improved part, but still inspect them on any high-mileage truck.
   easy$
3. Sway bar links and bushings
   Grab the sway bar end links and the bar itself and shake them. Loose links or dried-out bushings clunk over small bumps.
   easy$
4. Upper ball joints and control arm bushings
   With the wheel off the ground, pry on the upper arm and look for movement or cracked bushings. Replace worn arm bushings as a set rather than one at a time.
   medium$$
5. Shocks, torsion bar keys and mounts
   Check the shocks for leaks or loose mounts and look at the torsion bar arms and cross member bolts for rust and movement. Rust at the suspension mounting points is worth a closer look on any northern truck.
   medium$$

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Most shimmies come from tires, balance or worn front end parts. Do the cheap tire checks before replacing steering parts.

1. Tire condition and balance
   Look for bulges, flat spots and uneven wear, then have the wheels spin balanced. Cupped tires or a bent wheel can feel like a worn suspension.
   easy$
2. Tire pressure and rotation
   Set all four tires to the placard pressure and check for a tire that is out of round. Rotating the tires front to back can move the vibration and tell you which end it is in.
   easy$
3. Tie rod ends and idler arm
   With the wheels off the ground, push and pull each wheel at 3 and 9 o'clock. Any play here points to tie rod ends, the idler arm or the steering rack or box.
   medium$
4. Wheel bearings
   Grab the tire at 12 and 6 and rock it, then spin it by hand and listen for a growl. On 4WD trucks the front hub also needs correct lock and bearing preload.
   medium$$
5. Alignment
   After any ball joint or tie rod work, get a four wheel alignment. A truck with a lifted or sagging front end can also pull or wander until the torsion bars are reset.
   medium$$

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Trucks from salt states can have serious frame and body rust. The rockers, rear wheel arches and the areas around the suspension mounts are the usual trouble spots, and clogged sunroof drains can feed rocker rust.

1. Frame rails by tapping
   Tap along both rails with a hammer, especially near the rear cross members, spare tire carrier and suspension mounts. A solid ring is fine. A dull thud, flaking or a hammer that goes through means a repair is needed.
   easy$
2. Rocker panels and pinch welds
   Look at the underside of the rockers and the pinch weld seams for bubbling paint, holes or sagging. Press gently with a screwdriver handle at suspect spots.
   easy$
3. Rear wheel arches
   Feel the inside lip of the rear arches for rough scale or holes. Mud trapped behind the plastic liners hides rust until it is advanced.
   easy$
4. Sunroof drains
   If the truck has a sunroof, pour a little water in the tray and confirm it runs out below the doors. A clogged drain can soak the rocker cavity from the inside.
   easy$
5. Rust prevention and repair
   Clean loose scale, then treat with an oil or wax based frame coating or cavity wax each year. Structural repair of boxed sections is shop work.
   hard$$$

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On the 5VZ-FE the water pump is driven by the timing belt, so a weeping pump and an aging belt often go together. Start with coolant level, the radiator and the fan before pulling the front of the engine apart.

1. Coolant level and condition
   Check the radiator and reservoir cold. Low coolant means find the leak. Rusty or oily coolant points to long neglect or an internal leak.
   easy$
2. Radiator, hoses and cap
   Look for crusty residue at the radiator seams and hoses, and squeeze the hoses when cool for soft or swollen spots. Replace a weak cap, which is cheap and often overlooked.
   easy$
3. Fan clutch and fan
   With the engine cold, spin the fan by hand. It should offer some resistance and not free spin for long. A fan clutch that does not lock up when hot lets the engine overheat in traffic.
   easy$$
4. Water pump on the 5VZ-FE
   Look for coolant trails or residue at the weep hole near the front of the engine, under the timing belt covers. If the belt is due, replace the pump, thermostat and belt together.
   hard$$
5. Thermostat and block test
   A stuck thermostat is cheap to replace. If the truck keeps losing coolant with no leak, run a chemical block test for combustion gases in the coolant.
   medium$$

Go deeper: Toyota 5VZ-FE 3.4L V6: Full Specs, Common Issues & TRD Supercharger

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On automatic 4Runners from this era, the transmission cooler inside the radiator can leak and mix coolant with the fluid. Catch it early because coolant in the transmission wrecks clutch material.

1. Dipstick check
   Pull the dipstick with the engine warm and look for pink, milky or foamy fluid. Also check the radiator coolant for an oily film.
   easy$
2. Pressure test the cooler
   A shop can pressure test the radiator transmission cooler. Many owners just replace the radiator and cooler line seals at the same time.
   medium$$
3. Radiator replacement
   If the radiator cooler is the source, replace the radiator and flush the transmission cooler lines. Do not reuse old hoses that are cracked.
   medium$$
4. Transmission flush and inspect
   After the leak is fixed, the transmission needs a full fluid exchange and a look at shift quality. Slipping or burnt smell afterward means a rebuild may be needed.
   hard$$$

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The 3.4L 5VZ-FE uses a timing belt, not a chain. The 2.7L 3RZ-FE uses a chain. Treat belt service as scheduled maintenance and replace the water pump, idlers and tensioner at the same time.

1. Confirm the engine
   Check the VIN or the valve cover. The V6 is the 5VZ-FE and has a belt. The four-cylinder 3RZ-FE has a chain, so there is no belt to replace.
   easy$
2. Service records
   Look for a receipt that shows belt, tensioner, idlers and water pump. Toyota's interval is around 90,000 miles in later years. If there is no proof, assume it is due.
   easy$
3. Cover leaks and belt inspection
   Look at the front of the engine for oil from the cam or crank seals. Oil on the belt shortens its life, so fix the leak when you do the belt.
   hard$$
4. Replace as a kit
   Do the belt, water pump, tensioner, idler pulleys and front seals together. It is a lot of labor, so doing it all at once saves money.
   hard$$

Go deeper: Toyota 5VZ-FE 3.4L V6: Full Specs, Common Issues & TRD Supercharger

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Rule out the battery, terminals and grounds first, because those are free or cheap. Then move to the starter and the neutral safety switch.

1. Battery voltage
   Resting voltage should be about 12.4 V or more. Under 12 V, charge and load-test the battery before chasing anything else.
   easy$
2. Terminals and grounds
   Clean and tighten both battery terminals, the engine-to-body ground and the starter cable. Corrosion can mimic a dead battery.
   easy$
3. Shift position on automatics
   Try starting in Neutral. A worn neutral safety switch can block cranking in Park.
   easy$
4. Clutch switch on manuals
   Press the clutch fully and listen for the start relay. A failed clutch start switch will stop the starter from engaging.
   easy$
5. Starter
   A single click with a good battery usually means a worn starter solenoid or starter. Bench test or replace it.
   medium$$

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It needs fuel, spark and air at the right time. Check for spark and listen for the fuel pump before buying parts.

1. Fuel pump prime
   Turn the key to on and listen at the tank for the pump to run for a couple of seconds. No sound means check the fuse and the circuit opening relay, then the pump.
   easy$
2. Spark test
   Use a spark tester on a plug wire. No spark on any cylinder points to the igniter, ignition coil, distributor pickup or crank sensor.
   medium$
3. Fuel pressure
   Connect a gauge to the fuel rail test port. Low pressure with a running pump points to a clogged filter or a weak pump.
   medium$$
4. Distributor and wires
   Pull the cap and look for moisture, carbon tracking or a cracked rotor. Old plug wires can leak spark and cause a no start in damp weather.
   easy$
5. Read codes
   A crank sensor or fuel related code narrows it down quickly. Use a scan tool or jump the diagnostic connector to read flash codes.
   easy$

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On the 5VZ-FE a carbon fouled idle air control valve and throttle body is a common cause of surging and stalling. Also check vacuum lines and old ignition parts.

1. Throttle body and idle air control
   Remove the intake tube and clean the throttle body and idle air control valve with throttle body cleaner. Surging at idle or stalling when the A/C kicks on is the classic sign.
   easy$
2. Vacuum leaks
   Inspect the intake hoses, PCV hose and brake booster line for cracks. A leak can also set a lean code.
   easy$
3. Plugs, wires and distributor cap
   Old plugs and cracked wires cause a misfire under load. Replace them with the correct heat range as a set.
   easy$
4. Mass air flow sensor
   Clean the sensor element with MAF cleaner only. Do not touch the wire with anything.
   easy$
5. EGR and PCV
   A clogged EGR passage or stuck PCV valve can roughen the idle. Clean or replace the valve.
   medium$$

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The common ones on the 5VZ-FE are EGR flow (P0401), knock sensor circuit (P0325 and P0330), idle control and catalyst efficiency. Read the code before replacing anything.

1. Read and write down codes
   Use a scan tool. Note the code and any freeze frame data, then clear it and see how fast it returns.
   easy$
2. P0401 EGR flow
   Carbon often clogs the EGR passages in the intake. Clean the passages and check the EGR valve and vacuum modulator before replacing parts.
   medium$$
3. P0325 and P0330 knock sensor
   On the 5VZ-FE the sensors sit under the intake manifold and the wiring can go brittle. Inspect the harness first and use quality sensors if replacing.
   hard$$
4. P0420 catalyst efficiency
   Check for exhaust leaks ahead of the rear oxygen sensor and test the sensors before condemning the catalytic converter.
   medium$$
5. Gas cap and evap
   Make sure the cap clicks tight and the seal is not cracked. This is a cheap fix for evap codes.
   easy$

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Many 4WD trucks use a front axle disconnect that is vacuum operated. Perished vacuum hoses, a bad switching valve or a sticky actuator are the cheapest things to rule out.

1. Vacuum hoses to the actuator
   Follow the lines from the vacuum switching valve to the front differential actuator. Look for cracks, pinched spots or loose connections.
   easy$
2. Vacuum switching valve
   Check that it passes vacuum when the 4WD is selected. A stuck valve will prevent engagement.
   medium$
3. Front axle disconnect actuator
   Inspect for rust and a stuck shaft. Cleaning and lubing may free it, or the actuator may need replacement.
   medium$$
4. Transfer case shift and fluid
   Check the fluid level and the linkage. A tight or stiff shift may be a dry linkage or low oil.
   medium$
5. Test drive in 4 high on loose ground
   Feel for the front axle engaging. Binding on dry pavement is normal, so test on dirt or gravel.
   easy$

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Start with fluid level and condition. Then look at electrical and mechanical causes before assuming the transmission is toast.

1. Fluid level and color
   Check the level hot with the engine running in Park. Burnt smell or dark fluid means service or a deeper issue.
   easy$
2. Drain and fill
   A drain and fill with the correct Toyota fluid can improve shift quality on a truck with old fluid. Avoid a high pressure flush on a high mileage transmission with no history.
   easy$
3. Throttle position and speed sensors
   A failing throttle position sensor or speed sensor can cause erratic shifts. Check for codes.
   medium$$
4. Overdrive off light flashing
   A flashing light usually means a stored transmission code. Read it with a scan tool or flash codes.
   easy$
5. Radiator cooler leak
   If the fluid looks milky, see the coolant in the transmission symptom. Stop driving it until fixed.
   medium$$

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Sticking calipers and rusty brake lines are the usual problems on aging trucks. Inspect the whole system before replacing pads alone.

1. Pads and rotors
   Pull the wheels and look at pad thickness and wear pattern. Uneven wear side to side points to a sticking caliper or slide pins.
   easy$
2. Caliper slide pins and pistons
   Clean and lubricate the slide pins with brake grease. Check that the pistons move freely and the boots are not torn.
   medium$
3. Brake hoses and steel lines
   Inspect the rubber hoses for cracks and bulges and the steel lines for rust, especially on trucks from salt states.
   medium$$
4. Fluid and bleed
   Old, dark fluid causes a soft pedal. Bleed the system and flush with fresh DOT 3 fluid.
   medium$
5. Master cylinder and booster
   A pedal that slowly sinks points to the master cylinder. A hard pedal with a hissing sound points to the booster or its vacuum line.
   hard$$

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Valve cover gaskets are the most common oil leak on both engines. Clean the engine and find the actual source before replacing seals.

1. Clean and trace
   Degrease the engine, drive a short distance and look for fresh oil. Wetness at the top points to valve covers, and wetness lower points to the oil pan or rear seals.
   easy$
2. Valve cover gaskets
   Look for oil at the edges of the valve covers and in the spark plug tubes. Replace the gaskets and tube seals as a set.
   medium$
3. Oil pan and drain plug
   Check the pan gasket and the drain plug washer. A fresh crush washer is cheap.
   easy$
4. Cam, crank and distributor seals
   Oil at the front of the engine points to the cam or crank seals. Deal with them at the timing belt service on the V6.
   hard$$
5. Rear main seal and transmission
   Oil between the engine and transmission may be the rear main seal or a transmission leak. Check the source carefully before committing to the labor.
   hard$$$

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Worn u-joints and dry slip yokes are the cheap suspects. A whine or growl that changes with speed points to bearings or a differential.

1. U-joints and slip yoke
   Grab the driveshaft and twist it by hand, looking for play at each joint. Grease the slip yoke if it has a fitting and replace any rusty joint.
   easy$
2. Wheel bearings
   Jack the truck and spin each wheel by hand. A growl or roughness points to the bearing.
   medium$$
3. Front CV axles on 4WD
   A clicking noise while turning with the wheels cranked over points to a worn CV joint. Check for torn boots and flung grease.
   medium$$
4. Differential fluid and leaks
   Check the fluid level in the front and rear differentials and look for pinion seal leaks. Low or burnt fluid explains a whine.
   easy$
5. Pinion and carrier bearings
   A whine on drive or coast that changes with throttle usually means worn gears or bearings. This is a shop level diagnosis and repair.
   hard$$$

Go deeper: Toyota Regear Chart: Tire Size vs Gear Ratio vs RPM

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Check the battery and belt first, then the alternator output. A slow drain from an accessory can also kill a good battery overnight.

1. Battery test
   Have the battery load tested. A battery that won't hold a charge is the most common cause of a dead truck.
   easy$
2. Belt and tension
   Check the serpentine belt for glazing, cracks and slack. A slipping belt means low charging output.
   easy$
3. Alternator output
   With the engine running, battery voltage should be about 13.5 to 14.7 V. Much lower points to the alternator or its wiring.
   easy$
4. Connections and grounds
   Clean the alternator plug, battery terminals and engine ground. A loose connection can cause a charging light.
   easy$
5. Parasitic drain
   Put a meter in series with the battery after the truck sleeps for a while. Pull fuses one at a time to find the circuit drawing power.
   medium$

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