Hot answers tagged

40 votes
Accepted

Difference between OBDII and CAN

Ok, before I will answer your specific questions, let's do some introduction on bus systems. It could be that you know parts of these things, but I will start here as people with little or no IT or ...
user avatar
  • 1,281
23 votes
Accepted

What is the point of performing an OBD2 diagnostic scan if there is no malfunction indicator?

In most cases, unless things have been cleared, there's a good chance that if there was an issue previously, the codes will still be present in the ECU. Some codes are permanent (well, semi-quasi-...
user avatar
21 votes
Accepted

Can OBD-II be used to control the vehicle?

Ultimately the answer is yes you can. To qualify this answer, though, you can only control some things, but not all things, then only on some vehicles. You can do simple things through the port, such ...
user avatar
20 votes

Can a vehicle be harmed with bad inputs via an OBD-2 port?

It is highly probable that the reason your car was reluctant to start was that the time you were running diagnostics had sapped some of the charge from the battery. The battery on the car will not ...
user avatar
13 votes

Is it safe to get power from OBD 2 port for dash cam?

Maybe not answering your question completely, but: some people doubt how the OBD II connector is connected to power. The specification (SAE J1962 specification) of the connector is quite clear on this:...
user avatar
  • 131
12 votes

How useful is a low-end corded OBD-II reader for inspecting a used car?

There is a place where this reader can be useful. Know the age of the car, and your state regulations, to find out how many 'Not Ready' monitors are allowed before the car will fail emissions. If ...
user avatar
  • 8,612
12 votes

What is the point of performing an OBD2 diagnostic scan if there is no malfunction indicator?

Sometimes second-hand car sellers turn off or remove warning lights from dashboard in order to hide some problems, rather than spending money to fix them. Therefore, an OBDII diagnostic made by a good ...
user avatar
11 votes
Accepted

Disabling OBD2-Interface in a car

You're glossing over how the hack actually happens. The hack involves erasing the old keys and then reprogramming a new key to the vehicle. If the car uses a smart key then you're in right away. If ...
user avatar
  • 15.9k
11 votes

How do I go about troubleshooting DTC codes?

The computers in a car are constantly monitoring the operating conditions and sensors that are in the car. When a test fails or something goes out of a pre specified range a DTC is set. The biggest ...
user avatar
  • 15.9k
10 votes

Is control module voltage and battery voltage the same?

Looks like the issue is with the incoming signal. Unless your vehicle comes equipped with a flux capacitor, 65 V across battery is a bit too much. Even heavy trucks don't run that voltage to my ...
user avatar
  • 39k
10 votes
Accepted

What is the motorcycle equivalent of OBD-II?

Some motorcycles have a CAN BUS, some don't The OBDII connector type is simply a standard instituted by the SAE (Society of Automotive Engineers). In 1996 the US government mandated that all cars ...
user avatar
  • 32.8k
10 votes

Difference between fuel pressure and fuel rail pressure

On a car with fuel injection there can be two fuel pumps, one high-pressure and one low-pressure. The low-pressure pump moves the gas from the tank up to the high pressure pump. The high pressure ...
user avatar
  • 895
10 votes
Accepted

Do fault codes get recorded with a time stamp into a log with a history of DTCs?

It really depends on the implementation of OBD2. What my 1997 Subaru logs (virtually nothing) compared to a 2015 Chevy Cruise are entirely different things. However, in most cases, a Diagnostic ...
user avatar
  • 12.3k
10 votes

Would OBD-II devices drain the battery when used 24/7?

If the engine isn't running, then they surely will. I have an ELM 327 (Bluetooth) device which plugs into the OBDII port. Even when the vehicle is turned off, the device is active. Before I realized ...
user avatar
9 votes

Can a vehicle be harmed with bad inputs via an OBD-2 port?

To my knowledge there is no way a scanner can cause issues with your computer electronics. This device is a read only device. It doesn't change anything in your computer. It does, however, communicate ...
user avatar
9 votes
Accepted

Is it possible to auto close the power window of a car using OBD and CAN bus?

Everything depends on if the manufacturer multiplexed the windows or not. For example, General Motors tends to multiplex their windows. This means that every door has a module inside it. The module ...
user avatar
  • 15.9k
9 votes
Accepted

How to detect engine/ignition (on/off) status using OBD2?

Everything depends on exactly what your looking for. If engine running/not running is sufficient then check the RPM. If RPM is non zero, the engine is running. If the RPM is zero or no communication ...
user avatar
  • 15.9k
9 votes

Difference between OBDII and CAN

OBD II is a US government mandated diagnostic interface. This interface is guaranteed to provide a specific set of information including but not limited to engine computer data and engine computer ...
user avatar
  • 15.9k
9 votes

What does it mean when the ELM327 OBD2-reader gives two lines of info for 0100 request?

try this AT H1 this will turn on headers, then do 0100 you will get something like 7E8 06 41 00 BE 3E A8 13 7E9 06 41 00 98 18 80 13 which says you are getting results from ECUs 7E8 (engine) ...
user avatar
  • 241
8 votes

ATMA on OBDII not Working

Did you set the protocol for the chip to monitor on? e.g. ATSP5 for KWP-2000 or ATSP0 for "best guess". What about checking the headers as well - ATH1? I use the following string of commands to ...
user avatar
  • 1,965
8 votes

OBDII ELM 327 Bluetooth adapter - is it reliable?

The ELM327 is (almost?) as powerful as any other diagnostics solution. That's simply because it only translates the low level OBD protocols to some other format. Bluetooth connections on mobile phones ...
user avatar
  • 297
8 votes
Accepted

OBD-II difference between signal ground and chassis ground

You are over thinking things, just connect your devices (OBD & Pi) to a good chassis ground: The difference between chassis and signal ground is: Chassis Ground Pin 4: Is exactly that, ...
user avatar
  • 2,742
8 votes

What is the point of performing an OBD2 diagnostic scan if there is no malfunction indicator?

He can also look at fuel trims and other sensors performance. Some conditions on an engine may be efficient enough to keep the engine light off, but not in an ideal range.
user avatar
  • 2,692
7 votes

Any open-source OBD scanner analysis tools?

There's a lot of work going on in this space, so the answer is "Yes, Of course!" Here is a Python project: http://www.obdtester.com/pyobd This looks like an interesting way to get data from the car, ...
user avatar
  • 13.2k
7 votes
Accepted

OBD II power when key not in ignition

Pin 16 on the ODB-II connector is specified as "Battery Power" or "Battery Positive". There will always be 12v power between pin 4 and 16. Note that pin 5 has "ground" in the description, but that ...
user avatar
  • 13.2k
7 votes

Can we determine the Cleaning Requirement of Air Filter Using OBD

Modern gasoline engines have sensors to measure the amount of air that enters the engine. The ECU then injects fuel to give the correct mixture to get the most efficient burn. A dirty air filter ...
user avatar
  • 20.9k
7 votes
Accepted

Is it Possible to Control Lights through OBD-II Port?

The short answer is: no - not without the manufacturer's diagnostic tools. The long answer is: maybe. Modern cars have most (if not all) exterior and interior lights controlled by the body control ...
user avatar
  • 86
7 votes

2000 chevy cavalier cheap upgrades

If the question emphasis is on cheap, weight reduction is your friend For many reasons: A lighter car accelerates more quickly Because physics. Since you're planning to drag race, top speed should ...
user avatar
  • 39k
7 votes
Accepted

Controlling door lock/unlock via CAN bus

The OBD-II port supports a number of electrical protocols, but all of them are serial in nature. There is nothing you can do to any of the OBD-II pins with "plain negative pulses" to do what you want ...
user avatar
  • 9,286

Only top scored, non community-wiki answers of a minimum length are eligible