Just to note.
This is not the same resister Im speaking of but then again this copy & pasted info is listed as "O2 sensor harness warnings".
Not sure if the OPs car has the correct wiring so who knows what caused his EEC issue except for maybe VertVert LoL.
VertVert, the circult pictured above, do you know if its inline to the fuel relay also??
I know the 1 Im speaking does.
My understanding is there is several EEC grounds that go to different external components.
VertVert: The computers in our 5.0 Mustangs are all multilayer through hole PCB construction. if I remember correctly, there aren't any surface mount components in the PCB. Email me and I'll send you an A9L diagram and some information on the computer details.
To All: Perhaps my computer interchange note could have been better worded or arranged...
fordjunky: Two EEC grounds are present: the main power ground is on computer pins 40 & 60. The power ground starts out as 2 wires and terminates as 1 wire near the starter solenoid. It connects to the ground pigtail on the battery ground wire using a quick disconnect coupler. Due to its proximity to the battery, the quick disconnect coupler may become corroded by acid fumes from the battery.
In 86-90 model cars, it is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.
In 91-95 model cars it is a black cylinder about 2 1/2" long by 1" diameter with a black/white wire.
You'll find it up next to the starter solenoid where the wire goes into the wiring harness.
The computer case ground on computer pin 20 and grounds to the floor pan near the computer..
Diagram courtesy of Tmoss & Stang&2birds
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Mustang FAQ - Wiring & Engine Info Everyone should bookmark this site.
Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif
Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif
Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif
Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif
Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg
HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif
TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif
Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif