Toyota developed and used TEMS (Toyota Electronic Modulated Suspension) exclusively for a few products between the 1980s and 1990s.
TEMS is an electronically controlled shock absorber (Continuous Damping Control) based on various factors. On most of Toyota’s products marketed abroad, the semi-active suspension technology was extensively used on the luxury and top sport trim packages.
After the “bubble economy,” it lost favor because people viewed it as an unnecessary expenditure to buy and maintain, but it is still used on luxury or high-performance sports vehicles. Want to know which is better, Honda or Toyota? I prepared a detailed read here.
How Does Toyota TEMS Work?
The front and back shock absorbers’ damping forces are changed by TEMS using a microprocessor. As a result, the driver can select one of three control modes, and the suspension can be tuned in two phases (hard cushioning and soft cushioning) (AUTO, SPORT, NORMAL).
The TEMS technology has attained attitude controls in AUTO mode (i.e. squat control, roll control and nosedive control). The TEMS technology reduced the squat by 15 to 30%, the roll angle by 20 to 30%, the nose-dive by 10 to 30%, and the shift-squat by 30 to 40%.
Depending on how the system was installed, TEMS could be used in either an automatic or driver-selected mode and consisted of four shock absorbers mounted at each of the four wheels.
Top-tier Toyota vehicles with PEGASUS-branded four-wheel independent suspension came equipped with the technology (Precision Engineered Geometrically Advanced SUSpension).
TEMS was installed on cars with front and rear independent suspensions due to the nature of the technology. Although there were mini-buses or minivans like the Toyota TownAce/MasterAce, and Toyota Hiace at the top package were also TEMS-equipped cars with back-dependent suspension.
What are the Operation Parameters of TEMS?
The previous iteration, installed on two-stage TEMS in the 1980s, is described below in terms of how the system would activate.
- During normal running at 100 km/h (62 mph)
The system chooses the “SOFT” selection to provide a softer ride.
- At high speeds 85–100 km/h (53–62 mph)
The system chooses the “HARD” option and decides that it assumes a more rigid configuration at high speeds for better ride stability and to lessen roll tendencies.
- Braking (reducing speed to 50 km/h (31 mph))
The process continues to “HARD” automatically damping force until it detects the brakes are at the “SOFT” setting in order to avoid “nose dive.” When the brake light is turned off, and the pedal has been released for at least two seconds, it will return to the “SOFT” condition.
- (Only 3-stage systems) during hard acceleration
Based on the location of the accelerator pedal and the throttle, the system changes to “HARD” to prevent “squat” in the suspension.
- (Only 3-stage systems) during hard cornering
Based on the location of the steering angle sensor, the system switches to “HARD” to suppress suspension “roll.”
- SPORT mode
The system is always in the “HARD” setting, no matter the driving conditions. (In 3-stage systems, the system automatically selects between the “MID” and “HARD” configurations; the “SOFT” step is excluded.)
How Does TEMS Work on Roads?
The system would adjust the ride-damping force for specific circumstances based on the state of the road. The TEMS system was simply installed to fit ride comfort and road handling stability on small suspensions, adding a degree of ride modification typically found on larger, more expensive luxury cars.
Due to Japanese speed restrictions, the technology was initially created and calibrated for Japanese driving conditions; however, subsequent updates allowed it to be used in other countries.
What Caused the Decline in Demand for TEMS?
The system was viewed as an unnecessary expense as the early 1990s Japanese recession started to take hold and consumers began to prioritize basic necessities over perceived “luxury” goods and services.
On vehicles that were regarded as luxurious, such as the Toyota Crown, Toyota Century, and Toyota Windom, and sports automobiles, like the Toyota Supra and Toyota Soarer, TEMS installation was still possible.
Where Can You Find TEMS Now
TEMS is now only found in top-end Toyota models like Land Cruiser, Tandra, and other models, as well as Lexus models. Also, premium minivans like the Toyota Alphard, Toyota Noah, and Toyota Voxy have recently been equipped with the technology.
Recent names for the TEMS system include “Piezo TEMS” (using piezoelectric ceramics), “Skyhook TEMS,” “Infinity TEMS,” and most recently, “AVS” (Adaptive Variable Suspension).
The Toyota Starlet GT and other Toyota model lines offered this technology as an optional extra from the late 1980s to the mid-1990s.
The Starlet GT had two settings: a fixed sports mode and an automatic option, where the damping force adjusts itself in response to speed and other factors under the control of a separate ecu.
Unfortunately, TEMS was created using standard OEM shocks with fixed height, limited tuning options, and disposable damper designs, so you have to toss them away when they leak or break.
What are The New TEMS Features?
The system originally came with a two-stage switch with the label “Auto-Sport,” which was subsequently modified to read “Auto-Soft-Mid-Hard.” Some variations allowed the driver to explicitly choose the level of hardness they preferred using a dial. The “Auto” option was suggested for the majority of driving circumstances.
When the system was turned on, an indicator light showed the chosen suspension setting. Four shock absorbers, a shock absorber control actuator, a shock absorber control computer, a vehicle speed sensor, and a stop lighting switch, and only on TEMS three-stage systems, a throttle position sensor, and a steering angle sensor included in the system components. The degree of hardness that controls each absorber is the same.
Here are the latest TEMS features:
- Adjustable height-preload;
- Additional 8 damping adjustments;
- Active suspension option, sports mode, or automatic/comfort
- Rebuildable design.
In conclusion, Toyota TEMS is a remarkable technology that has been used in many of Toyota’s vehicles to provide a comfortable and smooth ride.
By utilizing advanced sensors and electronic controls, TEMS can automatically adjust the shock absorbers to suit changing road conditions, making the ride more comfortable and stable. This technology has greatly contributed to Toyota’s reputation for producing safe and reliable, high-quality, high-quality vehicles.
It is clear that Toyota is committed to constantly improving its technology, and we can only anticipate what innovative advancements the company will unveil in the future. As we look to the future, one thing is certain; the Toyota TEMS technology will continue to set the standard for comfort and performance in the automotive industry.