LOVE IT!!!
It is simple to use, cant use it enough. Glad i chose it over the 3120. Best product for the money, and then some.

Works great
Got this unit yesterday. Worked on both my OBD1 vehicles (Toyota and Ford) just fine. I was impressed with the extra tests for the OBD1 ford EEC.

Just beware those that buy this product, check the compatability with your vehicles before purchase, and update the software on the code reader.

Purchase a usb to serial plug also

how to update
My 3140 arrived with PC_SOFTWARE 1.32, and FIRMWARE 1.01
To update:
Install the software from the CD onto your computer, connect the tool to the PC, and turn on the tool. A "USB Serial Adapter" such as Keyspan High Speed USB Serial Adapter ( USA-19HS ) makes this much easier.
Select "Update" from the PC software menu --- and it will say a PC_SOFTWARE update is available, but your hardware is "up to date".
Download the new PC software (17 mb file), install, and run it.
Hit "Update" again now, and it will say that a FIRMWARE update is available. Download the new 'BIN' file (2 mb), and install it in the tool as outlined in the directions.
Currently I have PC_SOFTWARE 1.33, and FIRMWARE 1.02

This model is not worth the money
First of all, the model requires the purchaser to buy a serial to USB cable just to get use out of the software. The cable costs 35.00 but can be had for 20.00 if you search around. The 3100a costs 120.00 less and it comes with built in USB port and the cable. Overall, you're paying 150.00 more for OBD 1 functionality that according to another review is questionable.

My 3140 failed to diagnose my no-start problem. Perhaps no scanner will accomplish this. If a car is just running poorly I imagine the onboard computer will throw diagnostic trouble codes (DTCs) but unless it can start you may not see any DTCs.

One amazon purchaser noted that you should download version 2 of the firmware. I hooded up my scanner (after hunting around for the cable) and went to update it and the software kept sending me to the update site which showed no updates and gave no feedback. A couple days later the update site did work but it told me that version 1.01 is the latest firmware. When had I wrote for technical help I never got a response. My findings are that version 2 does not exist, there is only version 1.01.

My advise is to borrow a friend's scanner and see if that one works first. If that is not possible then purchase the 3100a and save a lot of money and time. I thought I was purchasing a higher end brand but this one is on par with a scantron you can purchase at any autoparts shop.

To be fair the live data does work but this is contingent on your engine running. I have yet to get the device to record live data from a running vehicle.

In summary, don't think the extra money spent on this tool will get you anything more that knowledge that you have a numerically higher model number.

ok for obd2 but obd1 beware
i recently purchased a 3140 scanner and have found it works really well on obd2 vehicles but on obd1 it has some short falls i own a 93 dodge truck and it will flash out 4 codes through the check engine light but the scanner only retrieves 2 of them i also tried it on a 92 chevy astro van with a egr code the scanner did not retrieve that code either i emailed the companys tech support a couple weeks ago about it and still have got no reply figured this might help some people considering their purchase p.s.it does not work on a 95 grand am with a 3100