Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [obd]

OBD means "On-Board-Diagnostics" for motor vehicles. Originally proprietary, there are now standards such as OBD-II and EOBD which define the connectors, electrical signalling systems and a standard set of messages.

On-Board-Diagnostics systems are now mandatory in vehicles sold in, for example, the US and EU. Originally proprietary, there are now standards such as OBD-II and EOBD which define the connectors, electrical signalling systems and a standard set of messages. The primary uses are obtaining real-time data from vehicle systems such as the engine management unit and retrieving diagnostic trouble codes (DTCs) that identify vehicle problems.

53 questions
7
votes
1 answer

Multiple devices on a CAN bus via the OBDII diagnostic connector in car

We have an aftermarket cruise control installed (in Suzuki Swift), which is connected to the OBD-II connector to access the CAN bus (according to the installation manual, it uses just CAN-L and CAN-H pins from the connector). Now I have bought an…
Marki555
  • 463
  • 1
  • 4
  • 12
6
votes
2 answers

Purpose of Zener Diode in Circuit

Can anyone please explain what the purpose of the zener diode is in the circuit shown? The circuit is taken from Figure 3 in the datasheet for the STN1170, an OBDII interpreter IC. simulate this circuit – Schematic created using CircuitLab DLC_RAW…
John
  • 329
  • 5
  • 12
5
votes
2 answers

How do I interface with OBD-II?

I've been tasked with interfacing with the on-board diagnostics of a vehicle. Some systems use 7V signalling, some use 5V signalling, some signal up to the battery voltage (which can be as high as 28 V on some bigger vehicles). I need some way to…
Thomas O
  • 31,546
  • 57
  • 182
  • 320
5
votes
1 answer

Firmware design for OBD2 - available PIDs request to ECU

According to many documentations, we can request a vehicle ECU to respond with the PIDs it supports. Link.My question is in the end. I have designed an OBD2 scanner using STM32 and CAN. And it works flawlessly when I use the broadcast request ID…
clamentjohn
  • 386
  • 3
  • 15
4
votes
1 answer

What do chips like ELM327 and STN1110 do?

What problems are the chips ELM327 and STN1110 solving? If I connect the necessary interface ICs (I mean dumb ICs, like level shifters, inverters, etc., not pre-programmed devices like ELM327) between the OBD pins and a suitable micro-controller,…
Dojo
  • 919
  • 10
  • 19
3
votes
1 answer

Reading and writing CAN messages through ELM327

I have an OBD-II cable, and an UART-to-OBD-II board which has the ELM327 IC in it. I want to communicate with my ECU by sending-receiving CAN messages. Is it possible to communicate through ELM 327? I've been able to diagnose the ECU to fetch basic…
user3098378
  • 33
  • 1
  • 4
3
votes
4 answers

Should I tie Signal Gnd (pin 5) and Chassis Gnd (Pin 4) together on OBD-II port?

I am building a OBD-II reader and wonder if I should tie these two GND together. What is the pros and cons of doing that? My device is powered by car battery and it reads OBD-II protocols through OBD-II ports. Thanks.
jsmith0910
  • 649
  • 1
  • 5
  • 15
3
votes
2 answers

OBD port power source

I've read on forums that OBD port can provide max 5A current at 12V. What is the source of the power? Is it coming from battery directly or is it regulated power supply from somewhere else, maybe ECU? Also if the source is battery, what is the…
Lalit Kumar
  • 43
  • 2
  • 5
3
votes
1 answer

Can I connect to my car's CAN bus with an ELM327 interface?

I've been fiddeling around with a Bluetooth ELM327 device I bought a few months ago and am able to get standard OBD information like vin, rpm, speed, etc. But as I just read about recently, OBD-II and CAN are not the same. I've tried to sniff on my…
Beejay
  • 31
  • 1
  • 2
3
votes
2 answers

Get current gear from rpm and speed through OBD2

I would like to modify my car with the help of Arduino to display the current gear. I wasn't quite sure where should I post this question as it is a car topic, as well as an electric engineering and mathematics topic. I want to get the engine rpm…
randddom games
  • 31
  • 1
  • 1
  • 2
2
votes
1 answer

CAN Bus sniffing

I am CE major prototyping embedded hardware to read and send data via the CAN bus. The design is coupled with a GSM/GPS module to enable tracking. I needed an EE perspective on the schematic diagram (minor changes made to existing designs). Why it…
user_Mac
  • 23
  • 5
2
votes
0 answers

OBDII Which hardware and software allows scripting via unix terminal

I developed an embedded design with dsPIC processor, which is a remote start module, communicating via 6 CAN busses. Often I would need a much quicker, simpler solution to test something on CAN bus, without writing compilable program. I need an Unix…
EmbeddedGuy
  • 548
  • 2
  • 15
2
votes
3 answers

CAN bus terminal

I have a CAN bus network that I want to test. I want to send CAN messages over my computer and see the responses. I have a Microchip kit with CAN that sends the responses over USB Mini and can be read by their application. I don't know in what…
rnunes
  • 831
  • 2
  • 11
  • 21
1
vote
2 answers

Reading from CAN bus of a Chevrolet Cruze using an Arduino Uno

I'm using the Arduino Uno, CAN bus shield, and OBDII to DB9 Cable using their provided libraries. I was only able to initialize it. Readings: While connected to the car: CAN-High: 2.7 V - 3.0 V CAN-Low: 2.4 V - 2.7 V While not connected to the…
mabdrabo
  • 185
  • 3
  • 9
1
vote
2 answers

K-Line vs CAN bus

I'm building an app (running on a Pi) that will communicate with consumer vehicles for diagnostics and control. I assumed that I could achieve this over CAN bus since all vehicles after 2003 are required to support OBD (which I assumed worked over…
TSG
  • 127
  • 8
1
2 3 4