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.

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Getting 45.6 Ω when it should be 60 or 120 Ω on CAN bus

We have a 2011 Chrysler 6.1L Hemi SRT. We can not get any diagnostic reading at the DLC or OBDII port. We have checked all the wiring, fuses etc. Our readings at the DTC connector are as follows: CAN ...
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Possible OBD-II/OBD2 connections for development phases

Is there any paper/document that summarizes all connection scenarios or cases when you are developing an OBD-II/OBD2 project for automative/car electronics? For instance, Scenario 1 : Real car -> ...
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Can an auto reset fuse and capacitor save my tracking device from surges while keeping it running?

I work with a few tracking devices and the newest model keeps popping. I've narrowed it down to possible short term current spikes in the trucks they are installed on. The device receives power from ...
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1 vote
1 answer
72 views

Unable to get identify CAN-H and CAN-L pinout from voltages & resistances measured at OBD-2 port

I am trying to figure out the CAN-H and CAN-L from OBD2 port fixed below the Dashboard. I unable identify CAN-H & CAN-L as I get following inappropriate voltage & resistance values which are ...
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1 answer
646 views

0x7E8 to 0x7FH on the CAN bus?

I am currently trying to understand the working of the CAN bus. I understand that when we connect a CAN bus logger to the OBD2 port in a car we will be able to view the CAN traffic (raw CAN frames) ...
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36 views

STN1110 UART-RX-LED is flashing rapidly

I did a pcb mount for a stn1110 "Multiprotocol OBD to UART Interpreter" and followed exactly schematic from datasheet. The issue I have is that after is starting, there is a sequence of ...
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0 votes
1 answer
195 views

Need help designing an OBD2 sniffer using an STM32 F446RE MCU

I have written a simple program that should send "NO MESSAGE!" to the serial monitor if there are no CAN messages or "A NEW MESSAGE ARRIVED!" and then the CAN message itself ...
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1 answer
113 views

Arduino still on after ground disconnected

I am using an Arduino to communicate with an OBD car scanner. It uses 2 digital pins for communication (7 and 11 SoftwareSerial.) I connected 12V power to VIN and GND. I also added ON/OFF switch in ...
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1 answer
106 views

OBD II Female connector with datasheet and measurements

I need an OBD II J1962 female port with 90 degree angled pins for pcb mount. I am struggling to find a part which has a data sheet or enough info so I can create a pcb footprint for it. Do you know ...
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1 answer
149 views

Some Physical Layers used with OBDII

I need to review some physical layers used in OBDII, a very common interface communication of vehicles and used as interface in a automotive scanners. I don't need exactly to know how the protocol ...
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1 answer
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Hooking up a device which is powered externally, to the OBD port of a car

I have a device called AutoPi (https://www.autopi.io) which is simply a Raspberry Pi Zero aggregated with a couple of more components. The device takes it's power from the OBD port. I want to make ...
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1 vote
2 answers
470 views

Selection criteria for microcontroller to read data from a car's CAN bus (from OBD2 to microcontroller)

I want to read data from a car's CAN bus using a micro-controller. The micro-controller is used outside the car (via OBD to micro-controller). A few micro-controllers i found with CAN interfaces are ...
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1 answer
387 views

CAN BUS Termination Resistors For CAN Logger Device

I am making a CAN logger device that will be connected to the vehicle OBD port. Since the CAN bus inside the vehicle is already terminated, do I need to terminate the BUS lines on my device end, right ...
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57 views

STN1110 LED1 keep flashing rapidly

I did a pcb mount for a stn1110 "Multiprotocol OBD to UART Interpreter" and followed exactly schematic from datasheet. The issue I have is that after is starting, there is a sequence of flashing the ...
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0 answers
57 views

I am trying to make a OBD logger for heavy-duty vehicles

The thing is that I have to use one CAN transceiver and one CAN controller. Both have one interface (CANH and CANL). I use dip switches to route different CAN signals whenever I need to using a DIP ...
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-1 votes
2 answers
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Identify rx/tx on an elm327 bluetooth adapter

Can you please help me to identify Rx / Tx pins of this OBD adapter in order to connect to it using an Arduino? I did that once with other adapter that looks the same on outside but different in ...
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2 votes
1 answer
755 views

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 (...
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-2 votes
2 answers
220 views

OBDII Car-Hacking

Can I implement an OBD-II scanner using an ATMEGA328P in place of the ELM 327? Preferably read some diagnostics code and upload that data to a web app via mqtt using GSM module.
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1 vote
1 answer
137 views

Getting garbage output in serial monitor while communicating with OBD using CAN interface (MCP2515) and nodemcu

I am doing a project which involves getting vehicle speed from a car's OBD port and storing it in my database using nodemcu. I am programming nodemcu using the Arduino IDE and using this library for ...
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0 votes
0 answers
91 views

Female OBD2 Connector

Does anyone know what's this exact connector: I got it from here, but I lost these metal connectors, and I was hoping to find them at DigiKey or similar sites, but the one that I was able to find is ...
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1 vote
2 answers
1k views

How to set timeout using AT commands and ELM327

I'm working on Android app that can read data from CAN bus. The interface I'm using is ELM327. The problem is that this interface uses Bluetooth, so I cannot read all the data from CAN bus because ...
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0 votes
3 answers
355 views

transistor or an SSR Relay as a Switch ? PCB

i want to create a switch that will turn on/off the power to my OBD Port on my car when i turn engine on/off. reason being i have an OBD wifi dondle plugged in all the time. problem is the OBD Port ...
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5 votes
1 answer
3k views

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 ...
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515 views

Help with ISO 14230 K-Line initialisation

I have an OBD-II scanner hardware built using STM32 and it is working fine with most vehicles.But I'm facing difficulty with ISO 14320 K-Line fast. Even though the firmware works fine when tested ...
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-3 votes
2 answers
246 views

Setup for logging/displaying what command an OBD scan tool sends

I came across this video: youtube.com/watch?v=VtMvccqE8ks Any idea/resources how to build this setup? I am not much interested in monitoring the CAN bus for commands (headers or CAN IDs) of power ...
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1 vote
1 answer
593 views

OBD-II and CAN bus broadcasting

I see a lot of Bluetooth adapters OBD-II reading speed, temperature, etc. Does that adapter read from the CAN bus with standard broadcasting? If read with standard broadcasting from the CAN bus, ...
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0 votes
2 answers
871 views

OBD-II bus - emulating the car side

TL;DR: If I connect one of these https://www.scantool.net/scantool/downloads/97/stn1110-ds.pdf directly (i.e. the CAN RX and CAN TX pins, plus overall 12 V power) to a device intended for a car (...
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2 votes
0 answers
49 views

OBDII Which hardware and software allows scripting via unix terminal [closed]

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, ...
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0 votes
1 answer
333 views

OBD STN1110 - Breadboard vs PCB Issue

We managed to hookup our hardware by following suggested design, and we wanted to use only CAN protocol. And on the breadboard with STN1110 DIP package everything works great on ECUSim 2000 simulator ...
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3 votes
4 answers
5k views

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 ...
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0 votes
1 answer
5k views

BDM pads on a Renault 450 DXI (EURO 5) Truck ECU

I'm trying to find the BDM pads for connection and map download from a Renault 450 DXI (euro 5) truck. Attached is a picture of the ECU. The control unit is MPC5XX ECU TRW EMS 2.2 Other details ...
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3 votes
2 answers
6k views

OBD port power source [closed]

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? ...
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1 vote
1 answer
2k views

Hook up bluetooth antenna to an Arduino (Or similar)

I have a Bluetooth ELM327 adapter that I am using with my car's OBD2 port. I have an Arduino UNO compatible Magpie (Little Bird Electronics) which I would like to use to interface with this adapter. ...
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1 vote
2 answers
5k views

Interpreting CAN bus data from OBD port

I'm using an Arduino with MCP2515 and MCP2551 to read data from a CAN bus over the OBD-II port of my car, Honda Jazz 2012. From what I've read on other forums and the OBD wiki, I can transmit the PID ...
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1 vote
1 answer
583 views

LPC2129 CAN bus interface to OBD-II

I want to connect an LPC to the CAN bus in my car, and I found that LPC2129 have the CAN protocol implemented on the chip. Searching the Internet, I saw that most of microcontrollers are connected to ...
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3 votes
1 answer
5k views

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 ...
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3 votes
2 answers
19k views

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 ...
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0 votes
2 answers
2k views

Fuel Injection Control through OBD port?

I am trying to implement remote control of a car, by connecting a GSM device to OBD port. If someone is using my car, I need to remotely stop the vehicle by sending command. Upon sending STOP command,...
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1 vote
1 answer
311 views

is the battery line on an OBD2 plug always on? [closed]

I'm looking at building a circuit that's powered by the OBD2 plug on a car. I can't seem to find if there are any specs around what the battery voltage pin does ...
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0 votes
1 answer
652 views

Bench testing OBDII dongle

I'm currently trying to connect my wifi obd2 dongle directly to a VW ecu that is powered by a bench power supply. I followed the guide here: http://www.nefariousmotorsports.com/wiki/index.php/...
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4 votes
1 answer
5k views

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) ...
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1 vote
2 answers
6k views

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&...
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3 votes
1 answer
9k views

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? ...
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6 votes
2 answers
3k views

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 ...
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-2 votes
1 answer
982 views

USB to OBD-II Converter

I want to make a scan-tool that works via a PC for my Thesis. To test it I have bought an ECU simulator (ECU-Sim 2000) with a CAN bus. I'm planning to make it using an FT232H USB to serial chip and a ...
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0 votes
2 answers
361 views

Circuits newb needs someone to help with a diagram

I'm trying to build an OBDII circuit for a STN1110 chip from OBD Solutions. My problem is I don't understand some of the values needed. For instance, the datasheet has most of the information I need, ...
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7 votes
1 answer
3k views

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 ...
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2 votes
3 answers
3k views

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 ...
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5 votes
2 answers
726 views

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 ...
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