You need to pick the signal to drive the electronic speedometer from the VSS wiring.
No info about your car's model year, EFI or carb, no mods listed. Makes it hard to troubleshoot when we don't know what you have.
Therefore, no clue as to which wiring diagram you need. The wiring changed several times between 79 & 95.
That's why it is a good idea to use the sig under the user control panel (User CP) option. It allows you to post your car year & mods, which help greatly when troubleshooting things. No, it is not there for us to snoop and see any "Secrets" you have hidden away under the hood. Be a good stangnetter and update you sig for future reference & don't keep us guessing.
PM me your email address and I will send you a complete Ford Factory 89 Mustang electrical diagram set. The zip file is 2.5 MB and is too big to fit through Stangnet's email gateway.
89 Mustang wiring diagrams zip package–
They are in a zip file format to reduce the size of the package. If you don't have Windows 7 or Windows 8, you’ll need WinZip or other Windows archive tool to extract them from the zip file.. See
www.majorgeeks.com - Download Freeware and Shareware Computer Utilities for a free download.
The diagrams show the location area and the connectors are drawn to the same shape as those in the car.
You will need the Adobe Acrobat viewer which is also a free download –
www.adobe.com/products/acrobat/readstep2.html - Adobe Reader download - All versions