I have a 89 GT and cant get my aftermarket radio to work.. The speaker harness is there, but the other harness was cut out. I dont seem to have a constant power wire.( i've checked w/ test light i just have ignition power) no ground wire, there are 3 0r 4 other wires there 2 of which have ignition power, no constant power though....getting really frustrated can anyone please help.....also no factory amp in car if that matters....thanx

 

Start simple, start with the fuses. Don't try and figure out if it is #5 or #6 just pull every single one and look at it, don't forget to look at the fuse box by the battery.

 

1988-89 Ford Mustang Stereo Wiring

Constant 12V+
Green/Yellow

Switched 12V+
Yellow/Black

Ground
Chassis

Illumination
Blue/Red

Dimmer
n/a

Antenna Trigger
Orange/Blue

Antenna
Right Front

Front Speakers
5 1/4"Doors

Left Front (+)
Orange/Green

Left Front (-)
Light Blue/White

Right Front (+)
White/Green

Right Front (-)
Green/Orange

Rear Speakers
5" x 7"Side Panels

Left Rear (+)
Pink/Green

Left Rear (-)
Pink/Blue

Right Rear (+)
Pink/Blue

Right Rear (-)
Green/Orange

See if this helps. Check your fuses. Worst case senario you may have to run your own power and just make your own ground.

 

If not, just go to the ignition harness and tap off the 12v constant wire...and run it to the radio. You can also tap off of one of the fuses if thats easier for you.

 

If you have to go to the ingition harness make sure you put an in line fuse on that wire.

 

the cig lighter is also a good place to find a constant, and yes a fuse is required.