- Safety first
- Never open the radiator cap or overflow when the engine is hot — hot coolant/steam can cause severe burns. Wait until cool (several hours) or carefully open only when cool.
- Wear nitrile or rubber gloves and safety glasses. Keep pets and children away from spilled coolant (toxic).
- Collect old coolant in a sealed container and dispose of it per local hazardous-waste rules — do not pour on the ground or down drains.

- What this job does, at a glance
- Removes old/contaminated coolant, flushes deposits out of radiator/heater/core and block, then refills with fresh coolant and properly bleeds air from the system.
- Typical reason: old coolant becomes acidic or loses corrosion inhibitors, which can damage water pump, radiator, hoses, heater core, thermostat and cause overheating.

- Estimated fluid volume (approximate)
- 1FZ‑FE engines commonly hold roughly 10–12 liters (about 2.5–3.2 US gallons) in the entire cooling system. Check a factory manual or measure what you drain to confirm before buying coolant.

- Tools you need (detailed descriptions and how to use them)
- Gloves (nitrile or thick work gloves)
- Protect hands from coolant and sharp edges. Put them on before you touch hoses or clamps.
- Safety glasses
- Protect eyes from splashes.
- Large drain pan (at least 6–10 liters / 1.5–2.5 gallons, sturdy)
- Slide under the radiator drain petcock or lower hose. Catch all coolant; transfer into sealable container for disposal.
- Funnel (wide-mouth automotive funnel)
- Use for refilling overflow bottle or radiator neck to avoid spills.
- Garden hose
- Used to flush the radiator and heater core. Screw to an outdoor faucet; push the nozzle or hose into the radiator neck (radiator cap off) and run water through until clear.
- Flat-head and Phillips screwdrivers
- Use to loosen/tighten screw-type hose clamps and accessory clamps. Use the appropriately sized tip to avoid stripping.
- Pliers (channel-lock / slip-joint)
- Grip and move hose clamps that are not spring-type, and pull hoses off when needed. Compress spring clamps with pliers or use dedicated clamp pliers.
- Hose clamp pliers (recommended but optional)
- Make removal and installation of spring-style clamps much easier and safer. Squeeze to open the clamp and hold it while pulling the hose.
- Socket set with ratchet (metric) — include 10mm, 12mm, 14mm sockets
- Remove drain petcock if it uses a bolt, remove thermostat housing bolts, remove lower radiator hose clamp(s), and possibly the fan shroud or splash shields. Use the ratchet for faster removal.
- Adjustable wrench / combination wrench set (metric)
- For bolts/nuts that a socket can’t reach.
- Jack and jack stands or ramps (optional)
- If you need room under the vehicle to access the lower radiator hose or block drain. Use stands — never rely on just a jack.
- Torque wrench (recommended if you remove any torque-critical parts)
- Ensures bolts like thermostat housing are tightened to spec. If you don’t have one, tighten snugly and evenly but do not overtighten.
- Wire brush or shop rag
- Clean mating surfaces (thermostat housing, radiator neck). Remove debris before reuse.
- Small flat tray or magnetic parts tray
- Keep bolts, clamps and small parts organized.
- Cooling-system pressure tester and refill/pressure-fill tool (optional, recommended for beginners)
- Pressure tester checks for leaks before you start the engine. A pressure-fill tool lets you pressurize and fill the system so it bleeds of air quickly and cleanly.
- Chemical radiator flush product (optional)
- If system has heavy rust or scale, a flush chemical helps dissolve deposits. Read and follow product instructions.
- Coolant tester/refractometer (optional)
- Confirms correct freeze/boil protection and concentration after filling.
- Replacement coolant (Toyota-specified or approved equivalent)
- Use Toyota-recommended coolant (check manual) or a compatible OAT/LLC type. Mix with distilled water 50/50 unless you buy pre-mix.
- Replacement parts (see separate section below)
- Have possible replacement thermostat, radiator cap, hose clamps, and hoses if they are old or leaking.

- Step-by-step procedure (bulleted actions)
- Park on level ground, set parking brake, and let the engine cool completely.
- Remove radiator cap/expansion tank cap only when cool to relieve any residual pressure.
- Place the drain pan under the radiator drain petcock (near bottom of radiator). If there is no petcock or it’s seized, be ready to loosen the lower radiator hose to drain.
- Open the radiator drain petcock (turn counterclockwise) or loosen the hose clamp and remove lower radiator hose to drain coolant into pan. If present, also open the engine block drain plugs or heater hose lower connection to help fully drain (only if comfortable).
- Close petcock or reattach lower hose after draining fully.
- If using a chemical flush: follow product directions — usually add the product to the radiator, fill with water, run the engine to operating temperature with heater on, then cool and drain. Dispose of the fluid properly.
- For a water-only flush: with the lower hose attached and petcock closed, insert garden hose into radiator neck and run water through until it runs clear from the lower hose or drain — you can run the engine briefly with thermostat open (see next) to circulate, but only after water is in system and engine is cool. Repeat fill/run/drain until clear.
- To circulate and flush heater core: after refitting lower hose, fill radiator/expansion tank with water, start the engine, set heater to max, let engine reach operating temperature so the thermostat opens, and run for 5–10 minutes. Then turn off, let cool, and drain again. Repeat until drained water is clear.
- After flushing and final drain, close drain petcock and reconnect hoses securely. Replace any hose clamps if weak or corroded.
- If you removed thermostat/plan to replace: remove thermostat housing, swap thermostat (spring towards engine usually), clean mating surfaces, install new gasket/seal, tighten bolts to spec or snug evenly.
- Refill with 50/50 coolant/distilled water (or pre-mix). Fill the radiator neck until full and fill the overflow/expansion tank to the cold “full” mark.
- Bleed air:
- With radiator cap off and heater on max, start engine and let it idle. Squeeze the upper radiator hose several times to help trapped air escape. Watch for air bubbles coming out of the radiator neck; add coolant as bubbles stop and level stabilizes.
- If your vehicle has a bleeder screw at a high point in the cooling system (check thermostat housing area), loosen it until coolant flows without bubbles, then tighten.
- When no more bubbles appear and temperature gauge is normal, replace radiator cap or close expansion tank cap.
- Run engine to normal temperature, rev slightly and watch for leaks, check heater output, and verify the temperature gauge does not creep toward hot. Check coolant level after engine cools and top off if needed.
- Clean up spilled coolant; store used coolant in a sealed container and take it to a recycling center or hazardous-waste facility.

- How to use key tools in practice (short how-to)
- Socket/ratchet: select the socket that fits the bolt, push onto ratchet, place on bolt head, pull handle toward you to break it loose; use extension if the bolt is recessed.
- Hose clamp pliers: position jaws over clamp ears, squeeze to open and hold while you pull the hose off the fitting.
- Garden hose flush: push hose end into radiator opening (radiator cap off), control flow so it doesn’t overflow, and flush until clear. Don’t force high pressure into a cracked radiator.
- Funnel: place securely into radiator neck or expansion tank opening and pour coolant slowly to avoid spills and air pockets.
- Pressure-fill tool (if available): attach to radiator neck, pump to prescribed pressure, and open valve to let fluid flow into a pressurized system which forces air out — follow the tool instructions.

- Parts that commonly need replacement, why, and when to replace
- Thermostat
- Why: Sticks closed or partially open with age causing overheating or poor heater performance. Replacing while flushing is inexpensive preventive maintenance.
- How to recognize: Engine takes very long to warm up or overheats quickly after warm-up. During flush, if you remove it, replace the gasket/seal.
- Radiator cap
- Why: Rubber seals harden and pressure rating declines; can cause boil-over or poor bleeding.
- When: If old, brittle, or if system loses pressure. Replace cheaply as preventive measure.
- Upper and lower radiator hoses and heater hoses
- Why: Rubber degrades, swells, cracks, or softens; leaks cause loss of coolant and overheating.
- When: If soft when squeezed, cracked, collapsed inside, or bulging; replace any suspect hoses.
- Hose clamps (spring clamps or worm-drive clamps)
- Why: Corroded or damaged clamps leak at hose ends. Spring clamps lose tension.
- When: Replace if corroded, broken, or no longer holds tight.
- Water pump
- Why: Bearings and seals wear; leaking pump or noisy bearing requires replacement.
- When: If coolant leaks from pump weep hole, or you hear a grinding/wobbling noise. Often checked during timing belt/water pump service.
- Radiator (rare but possible)
- Why: Internal corrosion, clogging, or external damage can reduce cooling ability.
- When: If repeated overheating persists after a proper flush and thermostat/water pump are good, or if visible leaks/damage exist.
- Drain plug gasket/O-ring
- Why: Old seals leak after reinstallation.
- When: Replace anytime you remove the drain plug or thermostat housing if a gasket is present.
- Coolant temperature sensor O-ring
- Why: O-ring can leak when disturbed; replace if you remove the sensor.

- When to use additional tools / recommended purchases
- Pressure-fill or vacuum-fill tool — recommended for beginners
- Why: Makes filling and bleeding the system nearly foolproof and fast; reduces trapped air which causes overheating.
- Cooling-system pressure tester
- Why: Checks for leaks in the radiator, hoses, head gasket and other components before you start the engine.
- Hose clamp pliers
- Why: Safer and much quicker to remove/install spring clamps; avoids hand fatigue and slippage.
- Torque wrench
- Why: For reassembly where the manufacturer specifies bolt torque (thermostat housing), to avoid warping or leaks.

- Tips & troubleshooting
- If the radiator water looks oily or there are white emulsified deposits, that can indicate head gasket failure — flushing won’t fix that; a compression test or professional diagnosis is needed.
- If, after flushing and refilling, the engine runs hot, re-check for trapped air (bleed points), thermostat orientation/installation, and leaks. Use a pressure tester if overheating persists.
- Always reuse only the specified coolant type. Do not mix incompatible coolant chemistries (IAT with OAT) — that can cause gelling or loss of corrosion protection.
- Keep a local disposal plan for old coolant — many auto parts stores accept used coolant.

- Quick parts checklist to have on hand before starting (recommended)
- Correct quantity of Toyota-approved coolant or pre-mixed coolant
- New thermostat (if old or >5 years)
- New radiator cap
- New lower/upper hose clamps or spring clamps
- Replacement lower radiator hose or any cracked hoses if present
- Small gasket/O-ring for thermostat and drain plug (if needed)

- Final reminder
- Follow factory service manual torque and bleed procedures if available. If any step or leak is beyond your comfort level, have a professional complete the job.

- Disposal (important)
- Store used coolant in a sealed container labeled “used coolant” and deliver it to a household hazardous waste facility or an auto store that accepts used antifreeze. Do not pour it down drains or on the ground.

If you want, I can give a condensed shopping list (exact sizes/clamp types) or a short checklist for bleeding order specific to your model — otherwise this covers the full procedure and parts to watch for.
rteeqp73

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Tools required
- Basic hand tools: Phillips & flat screwdrivers, 10/12/14 mm sockets, ratchet, extensions, combination wrenches.
- Trim removal tools (plastic pry tools).
- Needle-nose pliers, small picks.
- Multimeter (DC volts and ohms).
- 12V jumper wire or fused jumper lead.
- Test light (optional).
- Torque wrench (optional, for reassembly).
- Replacement shift lock solenoid/shift lock control assembly (OEM part for your year/model), replacement clips/screws if broken, possibly brake light switch if defective.
- Clean shop rags, dielectric grease, small container for fasteners.

Safety precautions (read before starting)
- Park on a flat surface, set parking brake, chock rear wheels.
- Shift to P and remove key.
- For electrical diagnostics you’ll need the battery connected. For removing interior panels or if you will disconnect SRS/airbag nearby, disconnect negative battery terminal and wait at least 2–3 minutes before working.
- Avoid forcing plastic trim (use trim tools) — plastic breaks easily on older Toyotas.
- When bench-testing the solenoid with 12V, use a fused jumper and only short bursts to avoid damage.
- Keep small springs/clips in a container so nothing is lost.

Quick system overview
- The shift interlock (brake-shift interlock) prevents moving the automatic shifter out of Park unless brake pedal is depressed. The brake light switch supplies the signal/power that energizes a shift-lock solenoid in the shifter/console. A common failure path: blown fuse, faulty brake light switch, damaged wiring/connector, or failed solenoid inside the shifter assembly.

Step-by-step diagnostic and repair

1) Initial checks (2–5 minutes)
- Confirm behavior: shifter won’t move out of P with brake depressed.
- Verify brake lights operate when pedal depressed. If no brake lights, suspect brake light switch or fuse first.
- Check relevant fuses (IGN and accessory fuses; consult fuse box legend). Replace blown fuse only after finding cause.

2) Check brake switch and wiring (5–10 minutes)
- With key ON, use a multimeter (20V DC range) or test light: probe the brake switch harness. There should be 12V on one terminal (ignition feed) and switching ground or 12V output on the other when the pedal is depressed (varies by car wiring). If brake light switch is bad, replace it (cheap and common).
- Adjust or replace brake light switch if the switch is out of adjustment.

3) Verify power to shift lock solenoid (5–10 minutes)
- Locate the shift lock solenoid connector at the base of the shifter (you may have to remove small trim to access or back-probe connector if accessible).
- With key ON and brake depressed, probe for 12V at the solenoid power wire (use back-probing). One side should get switched power when pedal is depressed. The other side should be ground.
- If no voltage at solenoid with working brake switch, trace wiring/connectors between brake switch and shifter or check ignition relay/fuse.

4) Confirm solenoid operation (bench/inline test) (5–15 minutes)
- If power is present at the connector but the shifter still won’t unlock, remove center console to access the solenoid (next section) OR carefully make a fused jumper from battery + to the solenoid power terminal while chassis ground on the other, with ignition ON and brake depressed — if the shifter unlocks the solenoid works. If it clicks and unlocks with direct 12V but not from brake signal, wiring or brake switch is intermittent.
- Use the multimeter to measure coil resistance: expect a low ohm value (tens of ohms). Open circuit or extremely high resistance = bad solenoid.

5) Remove console and access solenoid (20–45 minutes)
- If diagnosis points to a failed solenoid or internal shifter problem: disconnect battery negative (if you will be working near airbags or electronics).
- Remove shift knob: usually unscrew counterclockwise or pull straight up if it’s a press-fit. Some models have a retaining clip: pry carefully.
- Remove shift boot or bezel: pry up with trim tool, remove screws underneath (keep track).
- Remove center console trim pieces (cup holders, ashtray) and screws holding console to the floor. Use trim tools for clips. Keep connectors (seat heater, 12V) unplugged and labeled if needed.
- Lift console enough to access the shifter housing and solenoid assembly. Don’t force wiring harnesses.

6) Remove and replace the shift lock solenoid / assembly (15–30 minutes)
- Locate the shift lock solenoid on the side or rear of the shifter mechanism. It is usually held with 2–3 small screws or bolts.
- Note orientation of linkage, springs, pins. Take photos before removal.
- Unplug electrical connector, remove mounting screws, and remove the solenoid assembly.
- If replacing only the solenoid, transfer linkage parts/springs from old to new. If buying a complete shifter assembly, follow replacement unit instructions.
- Test new solenoid with 12V before reassembly (briefly energize to confirm motion).

7) Clean, lubricate, and reassemble (15–30 minutes)
- Clean shifter area of dirt and old grease with a rag. Do not use heavy solvent on plastic.
- Lightly apply lithium grease or gear lube to mechanical sliding parts (avoid getting grease on electrical connectors). A small amount of dielectric grease on electrical connectors is OK.
- Reinstall solenoid, reconnect connector, and reassemble console and trim in reverse order. Torque screws snugly but do not over-torque plastic bolts. Replace any broken clips.

8) Final testing (5–10 minutes)
- Reconnect battery if disconnected.
- With engine off and key ON, depress brake pedal and attempt to move shifter from P — it should release smoothly.
- Verify brake lights still work and that all console electrical items function.
- Drive test: ensure no unintended issues.

How the diagnostic tools are used (concise)
- Multimeter: set to DC volts (20V range). Back-probe the solenoid connector; check for 12V with brake depressed and key ON. Use ohms mode to measure solenoid coil resistance with connector disconnected.
- Test light: clip to ground, probe the solenoid power wire or brake switch output to see presence of power when pedal pressed.
- Fused jumper: connect fused 12V from battery + to solenoid power terminal while grounding other terminal to the chassis to energize solenoid manually (short bursts only).
- Trim tools: insert between panel seams, pry gently to avoid cracking.

Common pitfalls to avoid
- Breaking plastic clips and trim by prying incorrectly — use trim tools and patience.
- Testing with battery disconnected when you need live signal — don’t disconnect battery until you finish electrical diagnosis.
- Forgetting to fuse the jumper lead — can short and blow fuses or damage wiring.
- Misrouting or pinching the shift cable/harness when reinstalling console — can change shift feel or damage wires.
- Losing small springs/pins from the shifter linkage — take photos before disassembly.
- Over-greasing electrical components or getting heavy solvent inside solenoid—can ruin it.
- Not confirming brake light switch operation — most “interlock” complaints are brake switch or fuse related, not the solenoid.

Replacement parts typically required
- Shift lock solenoid or complete shift lock control assembly (OEM recommended).
- Brake light switch (if originally faulty).
- Any broken trim clips, screws, or shift boot components disturbed during removal.
- Fuse (if blown) — replace only after diagnosing cause.

If replacement is required, obtain the exact part for your year/model Land Cruiser/vehicle with 1FZ-FE (check VIN/parts catalog) — the solenoid is often sold as "shift lock actuator" or "shift lock control".

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