scan tool can't talk to ECU
 

I have a 1997 F150 w/ a 4.6L V8 and the engine light is coming on and it runs rough at around 50mph. The plugs were changed not too long ago and it ran great. Anyway, my problem for now is my scan tool can't find the ECU. I'm using a Konnwei that talks to an Android app called Torque. The scan tool works on another vehicle. I found in the wiring diagram that its fuse 12 at the top of the under dash fuse box. The fuse is good and 12v is getting to the DLC port under the dash. (green wire) Just to confirm, I peeled some insulation off of the green wire, took the fuse out and no 12v. Otherwise with the fuse in it gets 12v. https://cimg3.ibsrv.net/gimg/www.for...6b961d64ed.png
https://cimg5.ibsrv.net/gimg/www.for...18fe337a08.jpg

I'm thinking the next thing to check is tan/org, pink & ppl (pin 2,10 & 13 on the port and 16,15 & 13 on the ECU). The blue wire not show goes to air bag, remote anti-theft, abs & GEM. I can't really see where the connector to the ECU goes. Is that a connector I can remove? Any thoughts as to what the likely cause is before I start tearing into it further?

(side note: I replace 2 of the O2 sensors as a stab in the dark and reset the computer and it seemed to have fixed it but the problem returned)

Edit: Opps, I just realized it must be going to the PCM on the other side of the firewall:
https://cimg9.ibsrv.net/gimg/www.for...d4da9c5bd2.jpg

You need a elm 327 to make it work. Is your other vehicle a non ford product?

Yes, the other vehicle is a Pontiac. I've got another scan tool around here somewhere, I'll look.

I've got another scan tool I just ordered from BAFX. I'll try that tomorrow. If that don't work, I'll get a ELM. That's good to know before I go tearing into the wiring. Thanks.

Check the ground connections for the DLC port next, you've already checked the power side. If the ground then checks out, proceed to checking the signal lines for through continuity as well as confirming that nine of them are shorted to power, ground or each other.

"ELM" is the name of the company that made the original chips that the OBDII-BT adapters use internally. It's become a bit of a generic name since most of the Chinese products use knock-offs of the original ELM designs.

I went down to the local NAPA store and borrowed their scan tool and it seems to work so I guess I need a better scan tool. Of course now it doesn't show any codes because I had the battery disconnected last night when I was working on it.

I got the MIL to light up a couple times and I'm getting a misfire on cyl 6.

@sunbelt57 if you got a BAFX OBDII dongle, you should have no trouble getting Torque to work. BTW, you got the best scanner that you could have possibly bought. (If not the 'PRO' version, go get it.)

I notice you have another vehicle (Pontiac). Something you can do with Torque Pro that is VERY intuitive and productive (you've got multiple scanners in one). Under >Settings >General Preferences, increase number of dashboard screens (I use 15 - so I have equal number left<>right of center).

Then go to >Vehicle Profile and create a new profile for EACH of your vehicles (I leave the 'Default' one alone for using on my friends/neighbor's cars), and under each profile scroll down to the bottom to 'Advanced' and select >"Use a Separte Dashboard' for this vehicle".

Then with the Pontiac profile selected - download the GM/Pontiac custom PID set and set up gauges for your Pontiac - if you haven't already done so.

Then select your Ford - download the FORD Extended PIDs and set up screens for your Ford - if you haven't already done so.

You have TWO separate scan tools that will accommodate the maximum number of gauges / pids for each - and you can add more if you replace either one in the future.

Also, (there is significant differences in OBDII custom PIDs, even between different years of like vehicles), but you might find some helpful PIDs w/ formulas and a downloadable CSV file that I have worked out on Torque Pro for diagnosing MISFIRES (on 2004-2008 F150) located here:

https://torque-bhp.com/forums/?wpfor...opic&t=10826.0

Good luck and happy Torqueing