Repair Your Car Yourself — Which Toyota Diagnostic Tool is the Best?


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Motor vehicles have been equipped with more and more electronics in recent decades and can almost only be repaired with a Toyota diagnostic device. What devices are offered and how can you use them? In this article we want to offer you all the information you need to repair your Toyota yourself in the future!

From which year of manufacture is a Toyota diagnostic device required?

The Japanese corporation Toyota is one of the largest car manufacturers in the world today. In 2020 alone, more than 9.5 million vehicles were produced at the Japanese company’s plants. Today, Toyota is considered the twelfth largest publicly traded corporation in the world. Vehicles are manufactured by 400,000 employees at twelve Japanese plants and 51 locations in 26 countries. By 2020, Toyota was considered the most valuable automotive brand in the world.


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The first vehicles, the A1 and the GG Truck, rolled off the production line in the Japanese city of Toyota in 1935. Even though sales of the brand only began in Germany in 1970, Toyota’s market share in Germany was already over 5% in 2004 and even over 12% worldwide. Likewise, Japanese noble brand Lexus, which is manufactured by Toyota, is considered very successful and is one of the best-selling luxury brands in the USA.

The OBD and the Toyota diagnostic device

Since the 1970s, the U.S. has been one of Toyota’s most important sales markets. Even earlier, the company recognized the potential of the market and produced vehicles specifically for the American market. Due to increasing air pollution in California cities, the California Environmental Protection Agency ( CARB ) was forced to issue new vehicle emission regulations in the 1980s. However, the authority quickly realized that it was not sufficient to test new vehicles only for compliance with the exhaust emission standards. It was also necessary to develop a device to control the exhaust gas behavior of older vehicles. To this end, in 1988 OBD1 standard was adopted, which forced manufacturers of vehicles to integrate their own on-board diagnostics in the vehicles.

Starting in 1991, Toyota was required to integrate on-board diagnostics into vehicles with a gross vehicle weight rating of up to 7.5 tons. From this point on, these could only be checked with an appropriate Toyota diagnostic device.

The further development of the Toyota diagnostic device

The first OBD was developed so that the components of the exhaust system and their measured values could be easily queried and checked. This ensured that the exhaust gas regulations could be complied with over the entire period. Since then, however, automotive technology has constantly evolved. Accordingly, the OBD was also adapted to current needs.

OBD1 – in the first version of on-board diagnostics only the emission control ECU was addressed. Current values and the error codes of the control unit could be retrieved.

OBD2 – the second version of on-board diagnostics was introduced from 1994. At least since 1996, all vehicles sold in California have had to comply with these new guidelines. As the OBD1 system is primarily limited to emission-related components, the second version has not only been adapted to the new emissions directives, but has also been made more user-friendly for service technicians. From this version onwards, on-board diagnostics have been integrated into the vehicles’ on-board computers and, through a Toyota diagnostic device, allow all electronic components to be checked. The new directive also stipulated that a warning light must light up in the dashboard in the event of important problems. As a rule, the phrase “Check Engine” or “Service Engine Soon” is displayed. All important information and errors of the OBD2 are stored and can be read out via a Toyota diagnostic device. This gives technicians the ability to find and fix problems quickly.

EOBDon-board diagnostics has also been adopted in Europe. Called Enhanced On-Board Diagnostics, it is the equivalent of the American OBD2 directive. Both diagnostic versions are based on the same signal protocol and can be connected to a Toyota diagnostic device via the SAE J1962 diagnostic connector.

Repair car yourself - which Toyota diagnostic tool is the best?
Repair car yourself – which Toyota diagnostic tool is the best?

The OBD2 and the CAN bus

One of the main reasons why more and more electronics were used in modern automotive technology was the CAN bus. In older model vehicles, a central unit was installed that was responsible for the various functions in the vehicle. A major disadvantage was that it had to be installed at a central point in the vehicle. So it was necessary to connect them with many different data cables to the sensors and actuators in the vehicle. The wiring of these vehicles was very complicated and also caused some technical problems. The wiring was very sensitive and the smallest damage could paralyze the complete electronics of a vehicle.

Exactly at 7:00 p.m. in 1983, Robert Bosch GmbH began working on a communication system for motor vehicles. It was presented at an automotive conference in the USA in 1986. The CAN bus system or Controller Area Network enables communication between individual control units in a vehicle using just two cables. This eliminates the need for complicated wiring with hundreds of different cables, which are a major source of danger for a vehicle’s road safety. With the CAN bus, the individual control units can be installed at various points in the vehicle and receive and send data via the communication bus. Complicated wiring is therefore not necessary and all control units can receive data from the other control units and also send information.

Nowadays, up to 100 different control units are installed in modern motor vehicles to ensure safety and comfort in the vehicle. Nowadays, the OBD diagnostic connector is a part of a vehicle’s communication network and the only point through which a Toyota diagnostic device can retrieve data and fault codes from the vehicle.

What is a Toyota diagnostic device suitable for?

Over the past 20 years, more and more electronics have been used in motor vehicles. The advantages are obvious. Anti-lock braking systems, anti-slip systems and other electronic safety functions can only be realized with the help of electronics. Even an automatic climate control system relies on its own control unit if the temperature in a vehicle is to be regulated automatically.

However, the increased use of electronics in a vehicle also raises problems. Service technicians are no longer able to tell from the outside what problems and much function are occurring in a motor vehicle. There needed to be a way for technicians to quickly identify and fix problems. To this end, Toyota diagnostic equipment has been developed in recent years to retrieve information and data from the vehicle’s electronics and use it to troubleshoot problems.

The OBD2 diagnostic connector has proven to be very suitable for this purpose because it offers the possibility of directly accessing the various ECUs in a vehicle. More and more vehicle manufacturers are using this connection to develop Toyota diagnostic equipment that can communicate with the vehicle’s electronics.

What can be queried with a Toyota diagnostic device?

A Toyota diagnostic device can be connected to the vehicle electronics via the OBD diagnostic connector. This allows data and information to be read from the electronics’ memory. This allows the Toyota diagnostic device to connect directly to the on-board diagnostics. Not all information stored in the vehicle electronics is important for the repair of your Toyota. However, they can be used by an intelligent Toyota diagnostic device to produce interesting and important analyses.

However, one of the most important tasks of a Toyota diagnostic device is to read the error codes that the various ECUs have issued. OBD trouble codes are always composed of five characters and have been defined in the DTC (Data Trouble Code). In Europe, the DTC is standardized in the SAEW J2012 and ISO 15031-6 standards.

An OBD error code always consists of five digits. The first is a letter that specifies the particular system in which the error code was generated. Here is an example of the possible components where the error code could be generated:

Error codes do not necessarily always have to come from the DTC or the corresponding standards. Vehicle manufacturers can also define their own fault codes if required and use them to facilitate vehicle repair. To identify an error code that originates from a vehicle manufacturer, the second digit in the error code is used. A “1” indicates that it is a manufacturer specific error code and a “0” is used if it is a generic error code from the DTC.

The third digit in the error code is used to identify the component in which the corresponding error occurred. It can consist of a letter or a number. Here are some examples:

A Toyota diagnostic device can also be used to briefly evaluate faults that have been specifically developed by the manufacturer. They can serve as important information during a repair to help identify specific faults in a Toyota. Here are some examples:

P1300 Ignition circuit fault – No. 1.

P1310 Ignition circuit malfunction – No. 2.

P1335 No signal from crankshaft position sensor – engine running

P1349 VVT system.

P1400 Underthrottle position sensor.

P1401 Range/performance problem of the under throttle sensor.

P1405 Turbo pressure sensor circuit.

P1406 Range/performance problem of the turbo pressure sensor.

P1410 EGR valve position sensor – circuit defective.

P1411 EGR valve position sensor circuit range/power.

P1500 Circuit for starter signal.

P1510 boost pressure control circuit.

P1511 Low boost pressure.

P1512 Boost pressure high

P1520 Brake light switch signal malfunction.

What Toyota diagnostic equipment is offered?

There are now many different Toyota diagnostic devices offered in specialized stores. It is therefore important that you are familiar with the different types in order to make the best decision.

Handheld devices

Repair car yourself - which Toyota diagnostic tool is the best?
Repair car yourself – which Toyota diagnostic tool is the best?

Even before the OBD standard came into force, automotive manufacturers were working on diagnostic equipment to make it easier for specialist workshops to diagnose vehicles. In the early years, very bulky diagnostic devices were developed, which have become much smaller over the last few years. The result was the handheld Toyota diagnostic devices, as pictured here, which were sold by the automaker to authorized repair shops until 2005. This handheld Toyota diagnostic device was used to diagnose customer vehicles up until the early nineties. Handheld devices are equipped with their own monitor and have their own software with which the data can be read from the vehicle electronics.

Handheld Toyota diagnostic equipment is still offered today. They are often still in use in independent repair shops and are often recommended for their ability to diagnose multiple brands. The disadvantage is the relatively high price and that often an in-depth training is needed to operate these devices.

Toyota Diagnostic Device Software

Repair car yourself - which Toyota diagnostic tool is the best?
Repair car yourself – which Toyota diagnostic tool is the best?

Toyota, too, has been offering software for vehicle diagnostics to authorized workshops since 2006. The Toyota diagnostic device is supplied with different laptop versions and has its own cable so that it can be connected to the OBD diagnostic connector. The Toyota diagnostic device is offered in several versions. The “Light” version can only diagnose vehicles from 1996 onwards and is offered with a one-year subscription that allows all new Toyota models to be tested. The update is then only free of charge during the first twelve months, and must be paid for later. This Toyota diagnostic device comes with a very extensive manual. The technicians are usually offered special training for the operation of the device. It is not suitable for private individuals, as it is very expensive and is supplied exclusively to authorized workshops.

Mobile Toyota diagnostic equipment

Certainly the most practical and affordable solution for individuals who want to repair their own vehicle is a mobile Toyota diagnostic device. This technology harnesses the power of modern smartphones and tablets to analyze all the data stored in a vehicle’s control units. The power of modern cell phones allows diagnoses to be made that are not possible with other, often expensive, equipment. In addition, modern smartphones can provide a user interface that allows even inexperienced private individuals to efficiently and easily diagnose their vehicles.

A very good example of a mobile Toyota diagnostic device is the Carly OBD Scanner. With this device, only an adapter needs to be plugged into the OBD diagnostic connector and a connection via Bluetooth to the mobile device is established. This allows all vehicle electronics data to be uploaded to the smartphone in a short time. Immediately after this process is completed, the Carly OBD scanner will indicate whether errors were found with the colors red, yellow and green. If the color red is displayed, the user must immediately take care of the serious problems found by the Mobile Toyota Diagnostic Tool. If the traffic light color is green, no problems could be found. Yellow indicates when problems have been found that do not pose a safety risk to the occupants or the vehicle. The operation of the OBD scanner is very simple, although the device can offer much more information than conventional Toyota diagnostic devices.

What can be checked with the Carly Toyota diagnostic tool?

The Carly Scanner offers the possibility to read out all error messages from the vehicle electronics and provides understandable explanations. In this way, faults can be identified immediately and a quick and cost-effective repair can be carried out.

Since the Carly Toyota Scanner excludes all information from the ECUs, more extensive analyses can be made. For example, it is possible to determine whether the mileage of a vehicle has been manipulated. Since the mileage is stored in different ECUs and normal tamper devices only change the mileage in the central ECU, the Carly Toyota ECU can make a trustworthy analysis and identify falsified mileage.

Carly OBD scanner can be upgraded with different subscription models, so it can be used not only as a Toyota diagnostic device. Even in the basic version, many different car brands can be diagnosed and special functions for many different car models can be activated with special subscriptions. Particularly interesting for repairing one’s own vehicle is the Carly Smart Mechanic which provides users with detailed repair instructions prepared by experienced specialists. Diagrams and drawings are offered for this purpose, which can be very helpful for the repair and are normally only available to the technicians of the authorized workshops.

Toyota Diagnostic Device Conclusion

Nowadays, if you want to repair your vehicle by yourself and you are not willing to pay the high costs of specialized garages, you will only be able to perform simple repairs without a Toyota diagnostic device. This includes, among other things, changing the brake pads, work on the bodywork or replacing the tires. Already during the oil change the maintenance request of the vehicle electronics must be reset, for which a Toyota diagnostic device required is.

The simplest, cheapest and most practical solution is offered by the Carly OBD Scanner, as it uses the smartphone or a tablet for diagnostics. This makes it possible to quickly find all sources of errors and efficiently carry out your own repairs. The cost is amortized after a short time if a vehicle has been inspected several times. For repairs, the Carly Smart Mechanic is offered, with which even complicated repairs can be carried out yourself. The Carly Toyota diagnostic device costs only a fraction of the original diagnostic devices and offers private person the opportunity to repair their own vehicle like the professionals. The investment pays for itself after the first use, if the expensive man-hours for reading out the error codes in the specialist workshop are taken as a basis.

Keep in mind, that every car has different software and modules built-in. Therefore specific features will vary with every model.

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The device that every car owner needs.

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