Greetings to all,

I bought a cheap eBay OBD2 adapter and sure enough it would not connect with my Ford Taurus using Torque Pro. Frustrated, I took it apart to see what in it and how it was built, and here it is.

To open the case, you remove the plastic label which will reveal 4 screws which secures the top/bottom clam shell. Pretty simple.

The electronics is on a double-sided circuit board and generally very well constructed using quality components, presumably because components are machine loaded and wave soldered in an automated process.

Where it falls apart is the wiring to the OBD2 connector which is hand-soldered. There was a patch of solder splatter and a length of unmelted solder to one of the pins, but there were no open or short circuits, just very ugly. I cleaned it up and reassembled the unit but still no joy with connecting to the ECU.

Thank you so much, Ian! I will go through the modification information and hopefully get it to work. Will also report back.

My Taurus is a 2003 Canadian model with a 24V 3.0L V6 Duratec. I do believe it is OBD2 compliant.

Monty,
Thanks for the pics. Mine is the same adapter as yours. I did have one question, between the T2 and T5 I see some scratching and was wondering what you had to do there. Did you scratch between the two in a straight line or hook like red line or did you desloder the leg on T5 to hook up the wire like in “a”. Its just kinda tough to see what you “cut” on the board. I wanna try this so mine will hopefully work right.
Thanks for your help!

I understand, I think lol So all I really need to do is to scrape between the two transistors, then solder the wire correct?
The problem I’m having is not connecting to the ECU. Is that the same problem you were having? ELM327 is working fine on my friends Acura but gives me that error on my ’99 Ford Ranger.
Thanks again for the help!

Thanks again for the help Monty! I just finished mine but havent tested it yet. I’ll let ya know in the morning if I did it right lol Thanks a ton!

I don’t know if this is going to help anyone; I came across another Chinese OBD2 dongle which claims to work on all protocols as explained below:

The item is here:
http://www.ebay.com.sg/itm/OBDII-OBD2-diagnostic-327-1-4-wireless-Bluetooth-/280668420438#ht_4801wt_906

Looks like there are many permutations of the same basic product.

Hello!
I also have ELM 327 BT dongle with PCB board like right one from Monty_ picture, but there is not much at the back side of the PCB… it looks like http://imageshack.us/photo/my-images/198/20110803131410.jpg/
I have tested it on my Ford Mondeo TDCI 2002 diesel (Europe model) and it is not working with Torque PRO app on my mobile phone (dongle paired on Bluetooth but will not connect to Torque Pro).
Since I’m not expert in electronic I don’t know if it can be modified to work like you can with other versions.
Do someone know how to modified it?

Thanks

CWS, really glad it worked for you too. This confirms the mod. is legitimate at least for the particular model we have.

Here’s a picture of the power switch wiring – pretty basic but works. I thought about tapping a post-ignition point from the car but didn’t want the dongle tethered to it.

Dennis, there are apparently many variations of the same design that it’s difficult to say what your problem is, especially when schematics are not available.

The problem with my unit was a printed circuit board layout error – a pad that was supposed to go to ground was routed elsewhere. The error may have originated in the schematic. If that’s the case, it’s entirely possible that the same error has migrated to every permutation of the same dongle including yours.

Unfortunately there isn’t an easy way to verify this as it requires cross-checking of every unit. However, you can at least check if one leg of transistors Q3 and Q4 near the input connector is really connected to ground. Your picture shows it connected to an apparent ground plane, but it might not be connected to system ground.

This is just a stab at the problem from looking at your picture, Dennis, and probably worth checking if you have an Ohm meter (VOM) handy.

Dennis, that would be components “e” and “f” indicated in your picture, and their left leg as viewed in the photo appears connect to ground – that would be the patch of copper the legs are soldered to.

There are plated-through holes to connect the two patches to the other side of the board and should eventually snake its way to the main patch of ground plane, that would be the mass of copper everywhere on the board.

If in doubt, test for continuity of the two transistor legs to OBD2 connector pins 4 and 5 which is connected to vehicle ground. These pins should appear longer than the others when viewed from the front presumably because they will mate with vehicle ground first, when inserted.

Dennis, the two red arrows point to the transistor legs which (apparently) should connect to ground.

The three blue(ish) arrows point to (apparent) ground planes.

If you have an Ohm meter, test to see if all five arrow-head points are connected together.

Sorry I’m unable to be more clear with a better description.

Edit: On the blue arrow heads, you need to scrape off the green solder mask to reveal the copper underneath to test for continuity.