Computer Hookup?

Pinhead's picture
Submitted by Pinhead(2107)19 May, 2007 - 01:34

I have a laptop and like the idea of being able to track and change settings on my ECU. The Scan Gauge II would be a very nifty tool to have to watch instant mileage, etc., but doesn't offer any method of changing settings and is pretty expensive.

What are the best and where can I get a cable that goes from the OBDII connector to a USB or serial port? Where would I get the software to read these settings (I'd assume some [i]simple[/i] software would come with the cable)?

I saw a post where someone had an ELM323 ISO OBDII Interface, but googling only comes up with stuff overseas. Going to [url=http://www.elmelectronics.com/connect.html]ELM Electronics[/url] shows that I would need a ELM327, which is the "universal" one.

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Pinhead
Pinhead6 years 6 days ago

Computer Hookup?

Wow, I found the [url=http://www.scantool.net/products/product_info.php?cPath=8_6&products_id=32]ElmScan 5[/url] for $149.95...

RoadWarrior
RoadWarrior6 years 6 days ago

Computer Hookup?

Sorry I didn't jummp in sooner. Most ECUs have a serial protocol that standard serial ports can be persuaded via software to understand, however, RS-232 serial communications voltage levels are between +/- 12V and +/-24V while the output from ECUs is at TTL voltage levels of 5V, some may use 3.3V. Thus the most basic setup for serial communication between a PC and an ECU needs some kind of level convertor. A chip commonly used to do this is the MAX-232. It is also used for cellphone serial interfacing. Thus, if one wanted to do this on the cheap, one could make a simple level convertor circuit and wire the connectors up oneself. Given that a lot of convertors were used for older cellphones such as the Nokia 5x00 and 6x00 service and were mass produced cheaply in Asia, it may be possible to pick one of those up for cheaper than the price of the bits to build the electronics, and convert it to ECU reading purposes. It would already have a PC "end" on it, and one would just need to cut off the cellphone connector and fit a plug that can be used on the ECU connector, or splice your own hookup in with cheaper plugs.

It may be possible to use software to persuade a USB port to interface with a 5V ECU, but that might be dependant on the USB hardware. Usually the adapters have at least a buffer in them I think.

Anyhoo, glad you found what you were looking for.