This article is an excerpt from my book (MYODE - Make Your Own Diagnostic Equipment) for both DIY and auto-repair techs. The same software courtesy that I extend my readers, I will also extend to you here, as members of this forum. These are: Make the circuit, let me know, I give you a number, take a photo of the circuit w/number written in pencil, then get software from me, at no cost to you. Makes sense?
OBD-2 Data Link Connector Breakout Box
IMPORTANT NOTE. In this article and video, the Dataq DI-149 will be presented, which is separate from the OBD-2 DLC Breakout Box software.
![upload_2017-8-21_22-5-1.png]()
Did it ever occurred to you that you can diagnose lots of problems through the OBD-2 DLC connector. Things like, chassis or sensor ground issues. And we’re not talking about a simple open ground circuit. We’re talking about ground resistance and intermittent issues.
Well, we then present you with the OBD-2 DLC Breakout Box or Mr BOB DLC. This tool allows you to do all kinds of measurements on the DLC or OBD-2 data link connector pins. Yes, it’ll turn your PC, or Laptop into a virtual scope-like, measuring, and analysis machine. This gadget is a cutting edge tool, and it is the worlds best kept secret, when it comes to automotive data acquisition and component control.
The OBD-2 DLC Breakout Box, is based on the Dataq DI-149 board. This is a 59 dollar unit, that supports all Microsoft Windows operating systems. By itself, the DI-149 board does nothing. We need to connect a few extra components and, yes, it’s a done deal. Also, we need the software that runs the OBD-2 DLC Breakout Box, which will be provided to you by Mandy Concepcion, the developer of the OBD-2 DLC Breakout Box. Yes, and it’ll be free of charge, so long as you build the gadget yourself.
The OBD-2 DLC Breakout Box with Dataq DI-149 circuit has the following.
The OBD-2 DLC Breakout Box DI-149 is a product for general-purpose data acquisition applications, in a long line of low-cost starter kits from DATAQ. Suitable for measuring pre amplified analog signals, the DI-149 together with the included Mr BOB DLC software, allows real time data acquisition, playback, and analysis performance equal to, or better that other products that cost ten times more than its low price. This instrument has been sold to thousands of hobbyists and professionals, for countless data acquisition applications around the world.
The DI-149 has noise canceling, differential analog inputs, and are protected to 150 volts, well suited for automotive applications.
This is a tough and tolerant board, and used in conjunction with the OBD-2 DLC Breakout Box or Mr BOB DLC software and some extra components, it becomes a very capable tool.
Here’s how the OBD-2 DLC Breakout Box circuit works. Later on we’ll show you how to use it, and how to build it.
![upload_2017-8-21_22-9-35.png]()
The OBD-2 DLC Breakout Box is composed of the following. The Dataq DI-149, a few external resistors, diode, and a switch, and Mr BOB DLC software. That’s it, and then you put it together with the software, components and a PC or Laptop. This unit runs on a Microsoft Windows PC or Laptop, which today, almost everyone has. It doesn’t need much memory either. Any PC made within the last 12 years will work.
The unit also has a double ended OBD-2 connector, that you can build yourself. So, you connect the OBD-2 DLC Breakout Box to the OBD-2 connector, and then if you want, also connect the scan tool right behind it. It is that simple. Afterwards, install and start the OBD-2 DLC Breakout Box or Mr BOB DLC software on your Laptop. Don’t forget, this is a full USB device.
Here are the PC Board to OBD-2 DLC connector links. Pins 7 has two 10K resistor voltage dividers at the end. A switch is also part of the gadget, and one end of the switch also has a two 10K voltage dividers resistors. These are used to drop down the voltage and protect the gadget. Finally, the ground terminals are in series with a bias diode, done for protection in case of a accidental reverse connection to the battery. This gadget uses battery voltage and ground as reference to test all the OBD-2 pins.
The software for the OBD-2 DLC Breakout Box works as follows.
![upload_2017-8-21_22-10-50.png]()
![upload_2017-8-21_22-11-13.png]()
![upload_2017-8-21_22-11-32.png]()
![upload_2017-8-21_22-11-52.png]()
The OBD-2 DLC Breakout Box program has 6 sections. The first is the starter alternator tests. Connecting the OBD-2 DLC Breakout Box, and starting the engine is enough for the unit to run various tests on the system.
Many voltage drops tests are ran automatically, continuously, and very quickly. This section also turns your computer into a graphing multi-meter.
Then, there’s a network test section. You see, the OBD-2 connector is the central point of testing for the entire car. This is a continuous graphing section, meant to detect network issues.
Following, you also have the Voltmeter and Scope Graphing section, which turns the OBD-2 DLC Breakout Box into a very capable measurement unit. It’ll give you up to 8 channels of powerful measurements, which is more than what’s available on the market now. This is not a full fledged oscilloscope, but it is what you need to run tests on the OBD-2 connector. Any issues with a dead network will show up here, as well as power and ground issues. This is a fully visual section.
On the DLC pinout section you get various images to help you during diagnostics. Then, on the power tests, you can run all kinds of automated power tests, while seeing a power graph at the same time. This is powerful and deterministic of any drivability issues.
Finally, a dedicated ground unit testing section. It is estimated that at least 40% of vehicle issues is due to a ground problem. This is understandable, since the ground is connected throughout the car, at high resistance points in the chassis and engine block. With the ground testing section, you will know right away what’s wrong with your grounds, both chassis and sensor ground.
The OBD-2 DLC Breakout Box is a very capable gadget, that turns your computer into a virtual OBD-2 breakout box. It doesn’t communicate with the car. It is not a scanner, but a measurement device with automated tests, meant to help you with Power, ground, network, and all other issues that can be detected at the OBD-2 DLC connector. Since the OBD-2 connector is a standard, this unit will certainly provide you with many years of service for the foreseeable future.
Using the OBD-2 DLC Breakout Box
The OBD-2 DLC Breakout Box, is a device or tool, that allows for all kinds of testing on the OBD-2 DLC connector. It is not a scan tool, and it doesn't communicate with the vehicle ECM. It is only a measurement tool.
![upload_2017-8-21_22-12-32.png]()
There are many scenarios to use the OBD-2 DLC Breakout Box, such as testing the communication signals, or listening to the network traffic, between the different modules in the car. Also, to test chassis and sensor ground issues using voltage drop measurements, which is built into the OBD-2 DLC Breakout Box, power tests that can determine if the alternator, or battery is at fault, starter tests that measure the drain on the battery as the starter engages, and even running compression tests, based on battery draw from the starter motor.
Here are the scenarios where the OBD-2 DLC Breakout Box is useful.
Scenario One. Looking at the inter-module network signals or between scanner and ECM. The car isn't starting due to no spark, coil or injector pulse. This is important, because it’ll tell you right away two things. Imagine that the vehicle doesn't start. There are many possibilities for this to happen. First, you need to know if the ECM is alive. How? Well, by initiating a network call to it using your cheap OBD-2 code reader.
So, first go to the start network connector or main splice and disconnect all the modules, except the ECM. You then connect the OBD-2 DLC Breakout Box and the cheap code reader right behind it. At this time, you can view all the incoming and outgoing signals between the scanner and the ECM. If the ECM is not responding, and it has good power feed and ground, you know the ECM is dead.
But, more often than not, what happens is that another module or computer brings down the network. In cases like that, you then start to re-connect each module one at a time, at the star junction, while viewing the OBD-2 DLC Breakout Box. As soon as the shorted module is re-connected, the OBD-2 DLC Breakout Box laptop graphing voltmeter will show a signal drop. The OBD-2 DLC Breakout Box will save you the cost of buying an oscilloscope and pinching the OBD-2 connector wires, or damaging it in the process.
All the other scenarios for using this tool, are fully automated on the software. So, if you need to diagnose the power or grounds, it’s all done automatically. This is a nice tool to have if you want to tackle network, power and ground issues. The OBD-2 DLC Breakout Box usefulness, giving that the OBD-2 connector is standardized, will render many years of service to you.
![upload_2017-8-21_22-13-12.png]()
OBD-2 Data Link Connector Breakout Box
IMPORTANT NOTE. In this article and video, the Dataq DI-149 will be presented, which is separate from the OBD-2 DLC Breakout Box software.
Did it ever occurred to you that you can diagnose lots of problems through the OBD-2 DLC connector. Things like, chassis or sensor ground issues. And we’re not talking about a simple open ground circuit. We’re talking about ground resistance and intermittent issues.
Well, we then present you with the OBD-2 DLC Breakout Box or Mr BOB DLC. This tool allows you to do all kinds of measurements on the DLC or OBD-2 data link connector pins. Yes, it’ll turn your PC, or Laptop into a virtual scope-like, measuring, and analysis machine. This gadget is a cutting edge tool, and it is the worlds best kept secret, when it comes to automotive data acquisition and component control.
The OBD-2 DLC Breakout Box, is based on the Dataq DI-149 board. This is a 59 dollar unit, that supports all Microsoft Windows operating systems. By itself, the DI-149 board does nothing. We need to connect a few extra components and, yes, it’s a done deal. Also, we need the software that runs the OBD-2 DLC Breakout Box, which will be provided to you by Mandy Concepcion, the developer of the OBD-2 DLC Breakout Box. Yes, and it’ll be free of charge, so long as you build the gadget yourself.
The OBD-2 DLC Breakout Box with Dataq DI-149 circuit has the following.
The OBD-2 DLC Breakout Box DI-149 is a product for general-purpose data acquisition applications, in a long line of low-cost starter kits from DATAQ. Suitable for measuring pre amplified analog signals, the DI-149 together with the included Mr BOB DLC software, allows real time data acquisition, playback, and analysis performance equal to, or better that other products that cost ten times more than its low price. This instrument has been sold to thousands of hobbyists and professionals, for countless data acquisition applications around the world.
The DI-149 has noise canceling, differential analog inputs, and are protected to 150 volts, well suited for automotive applications.
This is a tough and tolerant board, and used in conjunction with the OBD-2 DLC Breakout Box or Mr BOB DLC software and some extra components, it becomes a very capable tool.
Here’s how the OBD-2 DLC Breakout Box circuit works. Later on we’ll show you how to use it, and how to build it.
The OBD-2 DLC Breakout Box is composed of the following. The Dataq DI-149, a few external resistors, diode, and a switch, and Mr BOB DLC software. That’s it, and then you put it together with the software, components and a PC or Laptop. This unit runs on a Microsoft Windows PC or Laptop, which today, almost everyone has. It doesn’t need much memory either. Any PC made within the last 12 years will work.
The unit also has a double ended OBD-2 connector, that you can build yourself. So, you connect the OBD-2 DLC Breakout Box to the OBD-2 connector, and then if you want, also connect the scan tool right behind it. It is that simple. Afterwards, install and start the OBD-2 DLC Breakout Box or Mr BOB DLC software on your Laptop. Don’t forget, this is a full USB device.
Here are the PC Board to OBD-2 DLC connector links. Pins 7 has two 10K resistor voltage dividers at the end. A switch is also part of the gadget, and one end of the switch also has a two 10K voltage dividers resistors. These are used to drop down the voltage and protect the gadget. Finally, the ground terminals are in series with a bias diode, done for protection in case of a accidental reverse connection to the battery. This gadget uses battery voltage and ground as reference to test all the OBD-2 pins.
The software for the OBD-2 DLC Breakout Box works as follows.
The OBD-2 DLC Breakout Box program has 6 sections. The first is the starter alternator tests. Connecting the OBD-2 DLC Breakout Box, and starting the engine is enough for the unit to run various tests on the system.
Many voltage drops tests are ran automatically, continuously, and very quickly. This section also turns your computer into a graphing multi-meter.
Then, there’s a network test section. You see, the OBD-2 connector is the central point of testing for the entire car. This is a continuous graphing section, meant to detect network issues.
Following, you also have the Voltmeter and Scope Graphing section, which turns the OBD-2 DLC Breakout Box into a very capable measurement unit. It’ll give you up to 8 channels of powerful measurements, which is more than what’s available on the market now. This is not a full fledged oscilloscope, but it is what you need to run tests on the OBD-2 connector. Any issues with a dead network will show up here, as well as power and ground issues. This is a fully visual section.
On the DLC pinout section you get various images to help you during diagnostics. Then, on the power tests, you can run all kinds of automated power tests, while seeing a power graph at the same time. This is powerful and deterministic of any drivability issues.
Finally, a dedicated ground unit testing section. It is estimated that at least 40% of vehicle issues is due to a ground problem. This is understandable, since the ground is connected throughout the car, at high resistance points in the chassis and engine block. With the ground testing section, you will know right away what’s wrong with your grounds, both chassis and sensor ground.
The OBD-2 DLC Breakout Box is a very capable gadget, that turns your computer into a virtual OBD-2 breakout box. It doesn’t communicate with the car. It is not a scanner, but a measurement device with automated tests, meant to help you with Power, ground, network, and all other issues that can be detected at the OBD-2 DLC connector. Since the OBD-2 connector is a standard, this unit will certainly provide you with many years of service for the foreseeable future.
Using the OBD-2 DLC Breakout Box
The OBD-2 DLC Breakout Box, is a device or tool, that allows for all kinds of testing on the OBD-2 DLC connector. It is not a scan tool, and it doesn't communicate with the vehicle ECM. It is only a measurement tool.
There are many scenarios to use the OBD-2 DLC Breakout Box, such as testing the communication signals, or listening to the network traffic, between the different modules in the car. Also, to test chassis and sensor ground issues using voltage drop measurements, which is built into the OBD-2 DLC Breakout Box, power tests that can determine if the alternator, or battery is at fault, starter tests that measure the drain on the battery as the starter engages, and even running compression tests, based on battery draw from the starter motor.
Here are the scenarios where the OBD-2 DLC Breakout Box is useful.
Scenario One. Looking at the inter-module network signals or between scanner and ECM. The car isn't starting due to no spark, coil or injector pulse. This is important, because it’ll tell you right away two things. Imagine that the vehicle doesn't start. There are many possibilities for this to happen. First, you need to know if the ECM is alive. How? Well, by initiating a network call to it using your cheap OBD-2 code reader.
So, first go to the start network connector or main splice and disconnect all the modules, except the ECM. You then connect the OBD-2 DLC Breakout Box and the cheap code reader right behind it. At this time, you can view all the incoming and outgoing signals between the scanner and the ECM. If the ECM is not responding, and it has good power feed and ground, you know the ECM is dead.
But, more often than not, what happens is that another module or computer brings down the network. In cases like that, you then start to re-connect each module one at a time, at the star junction, while viewing the OBD-2 DLC Breakout Box. As soon as the shorted module is re-connected, the OBD-2 DLC Breakout Box laptop graphing voltmeter will show a signal drop. The OBD-2 DLC Breakout Box will save you the cost of buying an oscilloscope and pinching the OBD-2 connector wires, or damaging it in the process.
All the other scenarios for using this tool, are fully automated on the software. So, if you need to diagnose the power or grounds, it’s all done automatically. This is a nice tool to have if you want to tackle network, power and ground issues. The OBD-2 DLC Breakout Box usefulness, giving that the OBD-2 connector is standardized, will render many years of service to you.
