OnStar Vehicle Diagnostics Technology

On-board diagnostics is a computer system that is built into cars.  With on-board diagnostics, the performance of your car’s major components is monitored and you get alerted if there are glitches or potential problems with your engine.  In the United States, on-board diagnostics have been required for all cars built starting from 1996 onwards.

Those driving earlier cars know on-board diagnostics as the idiot light, or that light that would come on to indicate malfunction.  Beyond that, you are left wondering what is wrong with your car.  Newer cars, on the other hand, can give you more details about what the problem is using standard diagnostic trouble codes and digital communications port.  With newer cars, you know for sure what the problem is and go straight to repairing it.

As such, on-board diagnostics is very valuable for repair technicians and mechanics in finding out what needs to be done and in pinpointing problems as it gives them important automobile data and diagnostics.  It is also very valuable for state agencies when it is time for vehicle inspection and maintenance.

However, on-board diagnostics is most valuable to the car owners.  Not only does it tell you that you need to have something repaired, it can also help you save money by identifying the problem early on while it is still a minor issue needing minor repair.  It helps you skip the trial-and-error part, too.

Benefits of on-board diagnostics

In short, these are the benefits of on-board diagnostics:

  1. Real time and accurate diagnostics that can alert you of potential problems and things that needs to be repaired.
  2. With on-board diagnostics vehicle inspections do not take too long.
  3. Fuel efficiency and better reliability because you can detect problems early on.
  4. Car manufacturers are encouraged to produce better engines and emission controls.
  5. As a testing method, on-board diagnostics is both affordable and simple.
  6. You can be sure that your car is safe for the environment because you are alerted about possible problems with your emission.

What’s more, compared to tailpipe inspections, on-board diagnostics offer more comprehensive fault detection.  This includes:

  • All emission-related problems that are monitored by on-board diagnostics
  • Cold starting problems
  • Evaporative emission problems
  • General conditions when operating the car

On-board diagnostics is also faster and more convenient.

How does on-board diagnostics work?

At the core of on-board diagnostics are sensors and actuators.  The sensors monitor your temperature, emissions and pressure, among others.
Critical parts of your on-board diagnostics include:

  • Ambient temperature sensor
  • Cooling system fans
  • Engine coolant temperature sensor
  • Fuel level sensor
  • Idle speed control
  • Mass air flow instrument
  • Powertrain control unit
  • Thermostat
  • Throttle actuator
  • Transmission control module
  • Transmission shift solenoids
  • Transmission speed sensors
  • Transmission temperature sensor
  • Variable length intake systems
  • Variable valve timing

Then you have the actuators, your ignition coils, throttle blades, fuel injectors, cam phaser and EGR valve.  Your on-board diagnostics also monitors your fuel injection system, exhaust gas cleaning system, canister purge system and ignition system.  Other major emission controls include:

  • Air/Fuel ratio sensors
  • Catalytic converters
  • Evaporative system integrity
  • Exhaust gas recirculation
  • Fuel vapor control
  • Secondary air injection

All of these are geared towards detecting increased exhaust emissions.  Some on-board diagnostics systems, however, also include monitoring other things that are related to just how well your on-board diagnostics works in general.  For example, the vehicle speed sensor is included in most on-board diagnostics because it helps ensure that you have accurate rough road detection that is used to create misfire analysis.  While the vehicle speed sensor has nothing to do with emissions, misfire diagnostics do.  And this is why on-board diagnostics have vehicle speed sensors built in.


The engine control unit or ECU.

These sensors and actuators are connected to an engine control unit or ECU.  Currently, a typical engine management system for a 4-cylinder engine that runs on gasoline has around 35 actuators and more than 25 sensors.  A direct injection engine would require a lot more.

All of these information are read by various applications plugged into the on-board diagnostics system.   There are hand-held scan tools that allow you to know what gives you the fault code when something is wrong.  You could also access the data on mobile devices.  To do this, you would need to connect your on-board diagnostics to your mobile device via USB or Bluetooth wireless connections.  You can then see the data on your mobile phone or tablet.

There are also desktop computer-based scan tools and analytics.  You plug in your on-board diagnostics to your PC via serial port or USB and the software performs analysis on the data that the system gathers, giving you a visual look at what’s happening in your car’s engine.  This is a good option if you want data logging and better understanding of your engine’s performance.
Lastly, there are the data loggers.  Data loggers are used to record information while you are using your vehicle.  You can use data loggers for:

  • Vehicle monitoring under usual operations.
  • Lower insurance premiums, because these data loggers can help show that you have good driving behavior.
  • Monitoring the behavior of your fleet’s drivers.

On-board diagnostics and telematics

Today’s on-board diagnostics systems are also used by the cars’ telematics devices to detect unsafe driving behaviors, track fuel efficiency and even tracking the fleet.  With telematics, on-board diagnostics also help bring on pay-as-you-drive insurance as well as remote diagnostics.

It is safe to say that today’s on-board diagnostics systems are very robust and can give you a lot of data and information about your engine and its emissions.  It has moved beyond simply being a data gathering and communication system to a platform with computing power that could rival your desktop computer, being able to communicate over mid-speed networks.  But even better, ECUs and on-board diagnostics have become standardized in that they follow the same protocols and use the same technical specifications.
This is why a Mitsubishi ECU can easily “talk” to a Nissan ECU.  And these standardizations help make improvements and innovations with on-board diagnostics possible and fast.

The future!

On-Board Diagnostics

A typical on-board diagnostics system.

When you buy a car today, you can take advantage of your on-board diagnostics directly from your dashboard.  For example, GM’s OnStar system talks to your on-board diagnostics to alert you of possible problems with your engine.  It can also know when an airbag is deployed and even unlock doors.

More than just determining problems, the future of on-board diagnostics would be more focused on safety.  When an airbag is deployed, your car would be able to call 911 and give them GPS details, and even a list of vehicle problems detected by the on-board diagnostics system.  This would be invaluable too and you would be able to give your technician a head-start should your car break down.  You could give them your on-board diagnostics data even before they get on site.
In the future, your car could detect if the Toyota ahead of it is having a malfunction and would be able to tell you about it.  This can help you avoid collisions and even allow you to help the other driver.

Speaking of help, could a DIY minor repair service be far behind?  Imagine being able to upload your on-board diagnostics data to a Web site and it analyzes the data and gives you a list of suggestions on how to do minor repairs on your car?

Repair shops would be able to wirelessly get your data and see if there is something that needs to be repaired.  They could send you an estimate and set an appointment date.  You could just accept or reject the offer, without you having to go to them.
And in the future, during an era of self-driving and autonomous cars, you do not even have to worry about driving your car.  Much less would you have to worry about potential engine problems.  A self-driving car would be connecting to the on-board diagnostics to see if there are problems and go straight to the repair shop if it detected something amiss. COOL – a driverless car that could automatically “deliver” itself to the technician if it has problems.

In terms of advancement, the transportation industry has been really slow.  Now that we have telematics and wireless communication that are not only readily available but are also low cost, things are definitely looking up.  The on-board diagnostics in your cars might not be a new concept as it has been around for decades now.  With new technologies, however, the on-board diagnostics you have will find other uses.  In fact, as the years go by, we can expect more functionality that takes advantage of the on-board diagnostics right from the dashboard.

On-board diagnostics simply has a wealth of data that can be used to offer more value added services to you, enough to make a carmaker take notice and work hard on developing applications for it.
And if you think that the future looks too science fiction, just imagine that until years ago, it was unthinkable to imagine having a driverless car, or a system that would allow you to know where a fleet of your vehicles are and whether their drivers are on their best driving behavior.  These things surely exist now, or at least very possible.

Photos courtesy of Rolls-Royce Power Systems AG and OnStar.

    Sherly Mendoza

    Sherly Mendoza is a banker by profession, but she's been blogging and writing tech articles since 2012. She's a woman fascinated with all things related to telematics, wearables, gadgets, the Internet, fashion, health and lifestyle. Sherly is also a new mom to a bouncing baby boy. She just gave birth last August 2013. Sherly reads and follows several tech and fashion blogs and websites. Some of them include Gizmodo, Engadget, Marie Claire and Pete Cashmore of Mashable. She's a Mac and PC user. Sherly is teaching herself on how to use the cPanel for website management. She's also fascinated with the Internet of Things, its applications and potentials. Sherly maintains her portfolio and blog at http://www.TechyFashionista.com.

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