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Understanding Toyota's vehicle control history

Thursday, August 1, 2019 - 07:00
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The Toyota Techstream scan tool offers technicians the ability to access an amazing wealth of information from vehicle electronic control units. On newer model Toyota and Lexus vehicles, the ability to access Toyota Vehicle Control History VCH) information is a valuable tool in no-code diagnostics. The VCH data also provides some incredible diagnostic data for technologically advanced systems such as Toyota safety sense.s

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The first time I ever attended a factory Toyota course, the instructor got on the subject of what he described as a black box technology, similar to that of today’s commercial airplanes, that store relevant data related to a crash should one occur. This black box data was only accessible via a Toyota field engineer and was not accessible through a scan tool. I can remember thinking how nice it would be if that data was actually available to technicians in some form as there are many times as technicians that we just simply don’t have enough information to properly diagnose and repair a vehicle. Fast-forward ten years and the idea of accessing ECU data that is not associated with a DTC is now becoming a reality on Toyota and Lexus Vehicles.

Vehicle Control History provides Engine Control “X” codes without setting a DTC – a great resource for no-code diagnostics.

Toyota has utilized Event Data Recorders (EDR) since 2000 when it began a rollout across the product line. Today, approximately seventy percent of the Toyota’s in the US are equipped with this technology- the subject of a 2016 Society of Automotive Engineers white Paper entitled Event Data Recorder Developed by Toyota Motor Corporation. The Toyota Event Data Recorder was developed to collect several collision analysis data parameters including pre-crash, side crash, rollover and pop-up hood pedestrian data. In addition to these parameters, Toyota also collected Vehicle control history data in a non-crash, triggered recording system. Federal regulations stipulate that this data must be available via a commercially available tool and Toyota worked with Bosch to utilize the crash data retrieval tool or CDR. Recently, Toyota began making some of the data available via their Techstream scan tool.

In the aforementioned white paper, Toyota stated that they felt that the evolution of this technology was forthcoming. For us as technicians, this is just the tip of the iceberg into how this data might help us.

HV operation history

Imagine yourself as a service advisor at a Toyota dealership in a busy metropolitan area in which a car count of over 100 vehicles is a normal day. Toyota has just announced a new model of the Prius and over twenty of these vehicles were delivered this week alone. The shifter technology has changed from previous model years and now includes a joystick shift function that is difficult to operate for some customers. After delivering the new vehicles to the customers, several have come back to the service drive complaining of transmission and shift related issues. The technician assigned to the repair order test drove the vehicle and found it to be operating normally and upon performing a Techstream health check there were no diagnostic trouble codes found in any of the modules. The service advisor reported the lack of findings back to the customer who is now displeased with the product and the dealership because the experience they had was perceived as a problem. In reality there may have been an error on the part of the customer in operating the vehicle.

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