OBD II Scan Tool using PIC micro

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JPKNHTP
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OBD II Scan Tool using PIC micro

Post by JPKNHTP » Fri Sep 09, 2005 12:49 am

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bodgy
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Re: OBD II Scan Tool using PIC micro

Post by bodgy » Sat Sep 10, 2005 3:07 pm

Elektor electronics had a project such as this recently.<p>The code can be downloaded free, and the single article can be purchased from their website.<p>Colin
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Re: OBD II Scan Tool using PIC micro

Post by Bob Lawrence » Sun Sep 18, 2005 8:57 pm

ELM Electronics makes it easy with their pre-programed chips:<p>For Example:<p>ELM322 - OBD (VPW) to RS232 Interpreter
Data Sheet pdf
322 Similar to the ELM320, and also completely revised, the ELM322 is for connecting to an OBDII equipped vehicle which uses the 10.4KHz J1850 VPW format. This standard is typically used in General Motors Corporation and some DaimlerChrysler vehicles. The user need only issue the desired commands through an RS232 serial connection and the data formatting, error checking, bus arbitration, etc. on the vehicle side is all taken care of by the ELM322. This allows experimenters to inexpensively create their own 'scan tool'. If you presently use one of our v1.x ICs, you will be pleased to know that this version is pin-compatible with the old, so you can simply replace your IC if you want to upgrade.

Available in: 8-pin PDIP $16.50 CDN, 8-pin SOIC $18.50 CDN<p>http://www.elmelectronics.com/index.html

mustang
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Re: OBD II Scan Tool using PIC micro

Post by mustang » Sun Oct 02, 2005 11:16 pm

Google to Harrison R&D. You can buy an assembled unit or buy the parts to build your own unit. The assembled unit works very well. Good Luck.

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Externet
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Re: OBD II Scan Tool using PIC micro

Post by Externet » Sun Oct 02, 2005 11:57 pm

Hi.
Check for item # 46030 here: http://www.harborfreight.com
It is actually $40. It is plausible to brew your own, but may be convenient to get it. I have it, I use it, and works.
Miguel
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Re: OBD II Scan Tool using PIC micro

Post by geewiz » Wed Oct 12, 2005 5:59 am

You may also want to check out http://scantool.net/

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Post by JPKNHTP » Sat Apr 01, 2006 5:28 am

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Chris Smith
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Post by Chris Smith » Sat Apr 01, 2006 7:40 pm

Back in the 80s, we plugged in a light bulb and counted the pulses. 3-2-3

Then we looked in the book for the code?

Has this changed?

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Post by jollyrgr » Sun Apr 02, 2006 4:26 am

Chris,

In answer to your question, yes, this has changed. I can tell you about my experience with GM vehicles and their diagnostics.

On GM vehicles you would short a pin on the interface (under the steering wheel ususally) to ground. If I recall it was pin A and surprise surprise Pin B was at ground. I'd have to look this up so don't go and try it!!!! But you'd short the pins together and turn the key forward without starting the car. A light on the dash, CHECK ENGINE usually, would then flash codes at you. Each code would be flashed three times. If I recall this correctly it was the code for 12 three times (all okay) followed by each diag code three times, ending with three more 12 codes.

In 1996 the switch was made to OBD II. This is a different connector and if there is a way to trick the on board computer to flash the codes, I have not been able to locate it.
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Post by JPKNHTP » Tue Apr 04, 2006 2:20 pm

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Post by connect21 » Thu Apr 06, 2006 10:26 am

If you use the ELM322 chip, how do you read OBD codes on your computer, do you need to get a particular program?

Thanks

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Post by JPKNHTP » Thu Apr 06, 2006 1:25 pm

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Post by philba » Thu Apr 06, 2006 4:45 pm

wow, it sounds like you done pretty well for yourself! I am very interested in schematics and so on.

Phil

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Post by JPKNHTP » Thu Apr 06, 2006 7:25 pm

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Post by Will » Fri Apr 07, 2006 2:26 pm

I know that more info is available than just the error (numeral codes) because a neighbour of mine who is a motor mechanic has a diagnostic tool which cost him about $4,000 and, apart from error codes, it reads all sorts of analog (Voltage) values which enable him to tune a vehicle while it is running. Is that sort of info available through these ELM chips ? I would be real interested in reading your tutorial
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