What is involved in hooking up a car to a home computer to SCAN It ? be it a OBD1 Or OBD2 ? How is it Done , and what will it actually tell you ? Thanks

If you are talking about the mutant 1994-1995 (some 1996 trucks)ODB1 or 1.5 you may have a hard time unless you have a scanner that can decode the data.
However if it is standard ALDL (1981-1993-4) there are ALDL to USB cables with software. Look up WinALDL. If you are going to connect it to a desktop, man you are going to need a long USB cable. I'm assuming you will be using a laptop.
For most 1995 and later, there are inexpensive "ELM327" chip based adapters. I've seen these advertised with USB or Bluetooth. Most are limited to Global ODBII data stream, but work. Most of the cheaper ones won't do make specific, body control and antilock(B and U code). Most will give P codes and Global ODBII data. O2, Map, Mat, MAF, VSS, EVAP, misfire etc. The stuff that makes them EPA/ODBII compliant.

If you are using an older laptop with an actual serial port then you can make your own cable very easily (small, simple circuit) and download some free software. However...if you only have USB ports then this makes life tough. For some reason, ECMs communicate at 8192 BAUD. This is fine for a serial port, but if it's a USB port (using a USB to serial converter) then you are stuck at 9600 BAUD so you can't communicate. The way around this is to use a UART chip within your cable circuit design. This allows you to set the BAUD rate fairly close to 8192 allowing communication flow. Unless you have a great electronics background, better off buying a pre-made cable.

Well you know there is a guy here who sells OBD1 diagnostic cables on this forum (phonedawgz).

Everything that follows is for GM OBD1 (US vehicles 82 - 95). In other countries GM ran OBD1 for many years after 96. Note the start year for all domestic cars for OBD 2 is 1996 (not 95)

GM Pin E ALDL vehicles (many 80s vehicles) are uni-directional. A 10K resistor between pins A & B start the data flowing. Depending on the type ECM used by GM, that resistor may need to be there just at the beginning to start the data, or must remain there. Pin E vehicles operate at 160 baud. The slower baud rate will mean the data on your laptop will update about once a second.

GM Pin M ALDL vehicles (late 80s and 90s) have a bi-directional data stream. A data request is sent on Pin M and the ECM responds. Generally the 10K resistor isn't required and many times does nothing. Pin M vehicles use a 8192 baud rate. It will appear that the data on the laptop will update as quick as a gauge.

GM Both Pin E & Pin M vehicles usually operate like the Pin M only.

Since Pin E is unidirectional, the circuitry is much simpler than Pin M. Make sure you don't use a Pin E (only) circuit for a Pin M application. Most simple transistor ALDL circuits are pin E only. Look for connections to both transmit and receive on the RS232 port for a Pin M circuit. If there is only a connection to receive the circuit is for Pin E only.

Remember with these circuits you will still need a USB to RS232 adapter or a RS232 (Serial Port) on your laptop

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If someone can tell me their definition of OBD 1.5 then I could tell you the differences between it and OBD 1. In my mind there is NO OBD 1.5. OBD 1.5 sometimes refers to ECMs that are flash programmable. OBD 1.5 sometimes refers to ECMs that return a different list of error codes than what was used before, however they still do it using OBD1 electronics and scanning hardware/software. Some call using the 16 pin OBD 2 TYPE connector on the OBD 1 ECMs OBD 1.5. Again it is still just OBD 1 but with a different connector. Add to that these changes weren't preformed specifically at one time. For example on the LT1 94 Camaro it uses the standard OBD1 12 pin connector, but it uses the updated error codes and the ECM is flash programmable. In 95 the same flash programmable ECM, programmed the same was used with a 16 pin connector. It all still runs OBD 1 electronics.

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TunerPro RT is by FAR the best program for scanning an OBD 1 vehicle. TunerPro RT is free to download. It runs 100% after a 10 second nag screen. If you wish you can purchase a license and avoid the nag screen however that is never required. I do include the 'free version' of TunerPro RT with my disk. You can also download it at http://tunerpro.net

TunerPro RT is free if you want it to be
TunerPro RT scans more types of ECM than any other program.
TunerPro RT allows you to modify and edit the data acquisition files if by rare chance your ECM isn't already defined
TunerPro RT gives you all the data numerically on one page if you want it
TunerPro RT gives you the ability to record and play back your data scan
TunerPro RT allows you to view the data in a real time or playback in a graphing format
TunerPro RT allows you to set up a histogram chart of the BLM (Long Term Fuel Trim), INT (Short Term Fuel Trim) and Timing Advance
TunerPro RT allows you to set up a full laptop DASH screen and allows you to define it and set up the gauges however you want. Most data acquisition files have dash pages already set up for them.

No other program free or for purchase has all these functions.

With ALL OBD1 scanning programs you need to use the correct data acquisition format for the vehicle being scanned. In TunerPro RT you do this by selecting a Data Acquisition File (.ADX). I supply with my cable the most comprehensive collection of .ADX files in a single place. They are also the most organized. Note - If you do decide to build your own, or even go with someone else's cable you can still download my disk and use the organized collection of .ADX files. At the bottom of this page there is a link to download my install disk including the .ADX files- http://reddevilriver.com/aldl.html

btw, no I don't have any connection with TunerPro RT other than including it with my OBD1 cables and then providing support for people trying to set it up.

So anyways there is my plug for my OBD1 cable. I do sell them in a USB to 12 pin version format, a USB to 16 pin format, and USB to a no-connector format that can be used on either connector. http://www.reddevilriver.com/aldl.html

Opel/Lotus Espirit connector USB version - http://www.reddevilriver.co...Lotus_USB_Cable.html

GM Holden (Australia) USB version - http://www.ebay.com/itm/110...id=p3984.m1555.l2649

Mitsubishi Diamond Star USB version - http://www.ebay.com/itm/121...id=p3984.m1555.l2649

Bluetooth to GM 12 pin ALDL adapter - http://www.reddevilriver.com/ALDL_Bluetooth.php

[This message has been edited by phonedawgz (edited 06-29-2014).]

Can the TunerPro be used with OBDII? I read their web site and in some of the release notes the talk about adding a plug in ELM327 adapter, but is was not clear that would work with OBDII. I have a bluetooth ELM327 adapter and an using the Android Torque app, but is would be nice to capture data on a Windows laptop.

Thanks
Frank

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What I "have" is a 1993 Firebird Formula (5.7) OBD1 that is driving me crazy. I will put my desktop on the front seat if I have to ! (no Laptop). Once the cable is plugged into the ALDL, put the disc in, then....? Are there instructions on the disc as "HOW TO USE IT " ??

quote Originally posted by Lou6t4gto: I will put my desktop on the front seat if I have to ! (no Laptop).

And your monitor on the hood? Should look interesting as you're driving down the street, with a REALLY long extension cord leading back to your house.

Beg, borrow or steal an old laptop. It'll make your life a whole lot easier in regards to running WinALDL or a similar program.

quote Originally posted by Lou6t4gto: What I "have" is a 1993 Firebird Formula (5.7) OBD1 that is driving me crazy. I will put my desktop on the front seat if I have to ! (no Laptop). Once the cable is plugged into the ALDL, put the disc in, then....? Are there instructions on the disc as "HOW TO USE IT " ??

Any chance you can go Android?

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I've got the ELM stuff too but since I already have two other OBD2 scanner programs I haven't messed with TP and OBD2 yet.

[This message has been edited by phonedawgz (edited 06-30-2014).]

Didn't realize that the car had to be moving !

Only if you want to see how the engine is running when it is moving. If you only care about how the engine is running at idle in the garage then it's fine to just do it in the garage.

quote Originally posted by Lou6t4gto: Didn't realize that the car had to be moving !

If all you want to do is look at the sensor data/movement at idle, then you could probably use a desktop computer, but if you want to troubleshoot things that happen while moving, then the car has to be moving.

You could use an inverter to power the home PC, but that is a lot of stuff to drive around with in the passenger seat. A laptop is much easier.

The most recent model laptop that I had with a serial port was a Dell Latitude CPi (PII). I'm sure one could be had on eBay for dirt cheap.

quote Originally posted by Lou6t4gto: Didn't realize that the car had to be moving !

They're pulling your leg.

Set your desktop on a table beside the car.
Start your engine and you can check for codes, and see the data your ECM sees.
It may help track down a faulty sensor that isn't quite right.

Older serial port equipped laptops are practically given away.
http://ocala.craigslist.org...ry=laptop+&sort=date

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Calgary time/temp

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[This message has been edited by fierosound (edited 06-30-2014).]

ALDLdroid - Make sure your Android device can support either Bluetooth, if that is the way you go, or USB Host Mode if you go with a USB solution.

https://play.google.com/sto...roux.aldldroid&hl=en

ALDLdroid isn't as robust as TunerPro RT but it has no problem functioning as a scanner.

Come to the conclusion, that I'll stick to" Physically Building Car"s, and leave the computer stuff to those that "Like It". I'm ok with my email and ebay, but even if I was able to bring up all that info on the screen, I wouldn't know what to do with it ! easier to pay someone $45 to do it and "They will KNOW what it means? Maybe if I had the opportunity to "Watch" someone " DO a SCAN", and explain it.... LOL Thanks anyway,