Electrical Mystery Wire For Ignition Switch

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StangNet's favorite TOOL
SN Certified Technician
Mar 10, 2000
Dublin GA
Copy and save these links, there is a lot of useful information there...

Diagrams courtesy of Tmoss & Stang&2birds

Ignition switch wiring

Starter circuit

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring; http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

94-95 Mustang wiring diagrams

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs

Ignition switch wiring

Fuel, alternator, A/C and ignition wiring

O2 sensor wiring harness

Vacuum diagram 89-93 Mustangs

HVAC vacuum diagram

TFI module differences & pin out

Fuse box layout

Mustang 5.0 Lights and Radio schematic, by TMoss:

87-92 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang87-92 PowerWindowWiring.gif

93 power window wiring

T5 Cutaway showing T5 internal parts

Visual comparison of the Ford Fuel Injectors, picture by TMoss:

Convertible top motor wiring http://www.veryuseful.com/mustang/tech/engine/images/mustang88VertTopMotorCkt.gif

Engine mounted fuel injector harness

Location of the TPS, IAB, and the 10-pin connectors on a 5.0, picture by TMoss:

Starter circuit


Active Member
Mar 7, 2016
Woodbridge, VA
Copy and save these links, there is a lot of useful information there
Thanks for the quick reply!

Those links are extremely useful. I have printed many of the diagrams and keep them in the car for quick reference (I also have the shop manuals, but the electrical can be frustrating because my wiring colors usually don't match the diagrams/pinouts:bang:).

In this case, I haven't found any diagram or forum mentions of the wire pictured. It looks like it was spliced into the red/green ignition wire by a previous owner and later severed. My plan is to cut out that butt connector and make a proper splice, but I don't know what to do about the stray wire. There's also a severed wire of the same gauge that terminates in the general vicinity of the ignition switch, but it's a different color so I'd assume it wasn't connected to the first wire. I will try to track that second wire to see where it leads. I just don't know what might have been spliced into pictured ignition switch wire at one time.


StangNet's favorite TOOL
SN Certified Technician
Mar 10, 2000
Dublin GA
It could be an alarm or other accessory since it was spliced in. At some point in time , the PO removed it and left the stub. That stub is a short circuit looking for a time to happen...
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