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Author Topic: Obd-ii Cable And Software  (Read 102 times)

Perplexer

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Obd-ii Cable And Software
« on: October 10, 2007, 11:02:00 PM »
After having the check engine light come on halfway through a four-hour drive last weekend (It turned out to be the althernator, specifically a damaged voltage regulator), I decided I am going to keep an OBD-II scanner with me at all times.

I could easily buy one of the handheld units, but for two reasons:
1. I am cheap.
2. I am a modder.

I would rather have something with more functionality... specifically a cable that I could hook to my laptop and get all sorts of neat data.

As far as handheld units go, Amazon has an Actron CP9135 for a good price.

I'm a little more confused on the PC cable issue.  Carplugs.com has parts and preassembled cables.  Only caveat is that on one of their product pages, they recommend an $80 interface which ""isolates your computer from the vehicle's electrical system. Plugging the cable directly into the PC may damage the serial port."

I don't want to damage my vehicle, or my serial port.  But this guy has a homebuilt cable which apparently works well as-is.  Hmm.

Anyone have any experience with OBD-II scanners or software?  Schematics or suggestions?

Thanks,
Plex
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beige

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Obd-ii Cable And Software
« Reply #1 on: October 11, 2007, 07:45:00 PM »
The cables scan tool companies sell are usually designed to be a direct interface with their scan tool. The cable itself doesn't contain the resistors or switching transistors that you need to make an ECM to PC interface. Those are contained in their scan tool.

If you don't have a serial port, you will probably have to buy a scan tool. I haven't seen a homemade interface that works with USB, so if you come across one, post a link to it.
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StrictPuppet

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Obd-ii Cable And Software
« Reply #2 on: October 11, 2007, 07:52:00 PM »
Even though auto manufacturers have had OBDII mandated since 1996 (in NA), they don't necessarily communicate with the same protocol for other controls other than generic code retrieval.  If all you want is to get codes, then a simple handheld device will suffice.  If you want to view other engine data, there are more expensive generic tools to do the job.  Many domestic models have been using a new higher speed protocol (called CAN) since around 2005. If you are looking for bi-directional controls, you will need more manufacturer specific tools/programs.

There are OBDII to usb cables available, which basically just have a serial port emulator built in, so serial port based applications will work with a usb cable.
Here is one I have... that can be picked up on ebay for very cheap..
IPB Image

There is a very nice app for VW cars available at http://www.ross-tech...-com/index.html which lets you view and alter many aspects of the powertrain.  This is actually a very sweet setup as certain VW's do not adhere to OBDII standards, even though they have the standard connector, and cannot be accessed in anyway other than the factory service tool.

Another site to check out is http://www.autotap.com/
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