The rear air suspension of the Prado 120 is quite common. Unlike the classic spring design, rubber cylinders filled with air are installed here. A system capable of changing hardness was also installed on the Toyota Land Cruiser 100, but its operation was ensured by a special fluid. In the Prado, this function is performed by compressed air .
The advantage of this suspension is that the ground clearance does not depend on how loaded the Prado 120 is.
The position of the body is closely monitored by two sensors, thanks to which the pneumatics maintain the required height. The adjustment occurs automatically; in addition, the driver has the opportunity to choose one of the three available operating modes . This allows you to increase off-road capabilities or improve handling on asphalt at the right time.
How to diagnose air suspension?
Pneumatic is a mandatory element of the Prado 120 - a common form of suspension for Toyota SUVs. The principle of its operation is simple: standard springs are replaced by air cylinders, which, depending on the position of the car in space, raise or lower the body. This suspension is installed only on the rear of the car.
The simplest diagnostic method is visual. If the cylinders are damaged, the rear of the SUV will sag. During operation, microcracks form in the rubber shell of air cylinders, allowing air to pass through. To make sure they are present, you need to moisten the cylinders with soap infusion. The air bubbles that form are a sure sign of a hole. Another way is to jack up the “healthy” car wheel. The part of the car with the damaged cylinder will remain in the air, and the cylinder will begin to slowly straighten, leveling the height. If there are cracks in the rubber, you will hear a characteristic sound with which air escapes.
Electronic problems
A common cause of air suspension malfunction is sensor failure: for some reason the system incorrectly adjusts the height of the car body. Therefore, before removing the air spring or valve block on the Prado 120, it is better to diagnose the “brains” of the car.
The simplest explanation: the automatic adjustment mode is turned on and incorrect parking. If the SUV is not parked level, but at an angle, then the next time it is “turned on” the system will consider this position to be “flat” and when entering the road it will try to return the car to a fixed state.
It happens that the height control sensor is capricious: due to malfunctions, it over- or under-injects pressure into the airbags, setting the wrong value for the body height.
The cause of the breakdown may be:
- contamination: cleaning is carried out with WD-40 or similar substances;
- contact fault: the sensor springs return to their original position;
- violations of the assembly order: after incorrect installation, the sensor may give erroneous readings;
- failure: “treated” by replacing the sensor.
Electronics do not tolerate frost well, so it is better to abandon automatic body height control at temperatures below -30.
The cause of the failure is often malfunctions in the fuses and relays responsible for the condition of the suspension. To get rid of the problem, it is enough to replace these elements.
How to configure the Land Cruiser 120 vehicle height sensor?
Attached to the car's frame, the ride height meter collects data from the body roll gauge. As a result, when adjusted correctly, the headlights rise or fall according to the time of day.
Vehicle ride height devices are called steering angle indicators. The movement of the wheel springs is sensed by the transverse arms of the suspension (front and rear) and transmitted to the Prado sensors, where the data is converted into a steering angle.
When setting up, the reference point is to use static electric and magnetic fields. The device produces a pulse signal and readings proportional to the rotation angle.
Repair and replacement of air cylinder
Working with the air spring is the most difficult part of repairing the Prado 120 air suspension. In most cases, it cannot be restored, but you can still try to fight for it.
To restore the cylinder, the rubber shell is cut off from it. In the best case, the repair will be completed by replacing the silent block. If the problem is in the clamps holding the pillow, they are sealed or tightened to reduce the outflow of air.
Replacement
The air cylinder is replaced as follows:
- The car is jacked up and the bridge is raised.
- The springs of the rear axle are tightened with ties.
- The lower shock absorbers are removed, the upper ones are weakened.
- Remove the strut stabilizers and kinetic suspension stabilization systems.
- The bridge is lowered.
- Pull out the spring with the air cylinder inside.
- The rubber bumper is cut off from the factory bumper bowl (inserted into the upper part of the spring).
- The bowl is cleaned of dirt.
- Holes are drilled in the bowl and cylinder corresponding to the holes in the upper part of the air cylinder.
- The bowl and cylinder are bolted together. The inside of the cylinder is hollow, so you can take bolts of almost any length. But it is worth remembering: if the bolts are too long, there is a danger that they will pierce the cylinder from the inside.
- An air supply tube is connected to the nipple.
- The system is assembled in reverse order.
Usually, air springs from BlackStone of size L are used as a replacement.
If the ride of the car after installing new cylinders seems too harsh, the spare wheel, connected to the system with a detachable connection, is made into a receiver. The rear wheel cylinders are thus combined into one circuit.
Compressor replacement
If the repair does not help revive the pneumatic unit, then there is only one option - a complete replacement of the Prado 120 compressor. To do this, you need to purchase a new spare part. Whether it is original or not is up to the owner to decide. The nuances of installing an analog compressor were written above.
You can replace the spare part yourself if there is a hole. Otherwise, the process will be somewhat delayed. The algorithm for removing the old compressor is described above. New - put in reverse order.
Source
Air suspension valve block repair
You can determine the malfunction of the Prado 120 air suspension valve block by the behavior of the car: if during a long stop the SUV “squats”, but returns to its original position when the engine is running, the problem is most likely in the valves that are leaking air.
- Raise the rear axle of the car and inflate the air springs.
- Remove the electrical contacts and the tube leading to the compressor from the valve block.
- Remove the receiver together with the block.
- To protect the wires and compressor tube from dirt, wrap them in a bag or cling film. Fix.
- Remove the compressor relay (to the left of the fuse box on the right side of the engine compartment).
- Remove the valve block by unscrewing the bolts. If the bolts are soured, moisten them with WD-40.
- Unscrew the valve block. Clean off dirt, replace seals and worn valves.
- To protect the block from dirt, coat the joints with sealant.
- Insert the valve block into the receiver.
- Connect the contacts and compressor tube.
Often, during the repair of a block, the plastic base into which the valves are screwed breaks. It won’t be possible to solder it: Prado owners claim that the plastic melts.
You will have to either purchase a new part or repair the old one with similar plastic and a hair dryer.
Air spring repair and replacement
Replacing an air spring on a Prado 120 is a relatively painless event, compared to other interventions in the air suspension. In the best case, everything will be done by patching microcracks that form during the operation of the car. The holes detected by the “soap test” are coated with sealant. To prevent the appearance of new holes, the pillow is impregnated with silicone.
If the rubber casing bursts while driving, you need to immediately stop and remove the one responsible for the operation of the compressor from the fuse box. If it is not turned off, there is a high probability that in addition to the need to repair the air springs, the replacement of the Land Cruiser 120 compressor will be added.
When completely replacing a pillow:
- Disable automatic suspension adjustment.
- Raise the car.
- Disconnect the compressor pipe from the receiver.
- Disconnect the airbag tube from the valve that regulates the suspension height.
- Raise the car higher, freeing the cushion.
- Remove the fork holding the air spring in the seat cup.
- Put on a new pillow.
- Secure the plug.
- Connect the valve pipe and the compressor pipe.
- Lower the car.
There is nothing complicated about how to change the air spring on a Prado 120. But sometimes, after tampering with the suspension, the computer refuses to work correctly.
To eliminate the problem, you will have to carry out diagnostics. The diagnostic block is located on the left side of the front panel, not far from the driver’s seat. A wire is connected to it, the other end is connected to a laptop with the diagnostic program installed. Any errors detected are corrected and the Prado operates normally again.
What is a hairpin and what are its features?
On every car, and Prado is no exception, special fasteners are used to mount the wheel disc to the hub - studs with nuts. The reason why they were chosen for mounting the wheels is simply explained. The developers set a goal to make it possible to install and remove wheels using a minimum number of parts. It was necessary that they secure not only the discs, but also the elements of the braking system.
As a result, with the help of this type of wheel fastener it is possible to perform several tasks:
- Attach the brake drum mechanism or disc to the hub.
- Connect the wheel disc to the hub.
- Center all these parts relative to the center of the hub.
- Increase the level of fastener reliability.
Despite the important role these parts play in ensuring machine safety, their design is extremely simple and the cost is minimal.
Price issue
The cost of repairing the air suspension in the cabin is high: just purchasing a cylinder will cost 8-10,000 rubles, depending on its originality. The cost of restoring an air spring is no less than 9,000. For work on just one side of the suspension you will have to pay at least 5,000 rubles.
Repairing breakdowns with your own hands is much cheaper: you only have to spend money on consumables.
Air suspension requires regular maintenance. For example, the average service life of cylinders ranges from 100 to 200 thousand km, and in off-road conditions and low temperatures they can be damaged even earlier. Level sensors often fail due to moisture ingress, and the compressor often fails due to overheating.
Installing a spring suspension instead of pneuma will save your Toyota from constant breakdowns.
Prado 120 air suspension control
The Prado 120 pneuma is controlled using a switch block . There is an “OFF” key on it, which turns off the automatic mode, and a knob that allows you to select one of the manual control options: high (HI), medium (Normal) and low (LO).
In HI mode, the ground clearance increases by 30-40 mm (the amount depends on the modification). This takes 15-20 seconds. In low LO mode, the Prado body squats by 30 mm in 10-15 seconds.
When automatic control is activated and the flag is turned to Normal mode , at speeds over 50 km/h the suspension will be in the middle position. If you drive slower, the ground clearance will increase as much as possible. When driving less than 12 km/h, the ground clearance will drop to a minimum, and vice versa.
Work order
On the Toyota Land Cruiser Prado 120, when replacing air springs, standard airbags and struts with adjustable stiffness are dismantled, and conventional shock absorbers and springs (from other trim levels or the “co-platform” 4Runner) are attached in their place.
For the Prado 150, you need a special adapter that will act as a lower support, and the help of a qualified diagnostician (otherwise there will be malfunctions in the stabilization systems and KDSS).
If you decide to upgrade the chassis of your SUV, come to our Toyota service center network. Our specialists have already accomplished more than one successful remodel. Correct selection of the characteristics of new parts allows you to achieve high levels of comfort and controllability, as well as significantly increase the reliability of the car.
