i just purchased an 89 GT, the previous owner installed new aftermarket head and tail lights, now when you pull back on the turn signal to just flash the lights the damn fuel pump turns on without the key even in the ignitoin. also the oil and fuel gauges dont work at all and the voltage gauge is reading really low (below 12 volts running down the road)

 

Well I would start by checking the charging system first.

 

Oil and fuel could also be the sending units.

But I would begin by testing the charging system as well. If ou do not own one, get a voltage meter and learn how to use it. Then find a weekend when you have tons of time and don't need to drive the stang anywhere. Electrical issues like that take some time and can be a PITA.

I personally don't like ford stock guages. Get a mechanical guage and put it on to make sure you have good Oil Pressure, and then you can feel a little better about driving it without the factory guage working.....

 

I found out that the steering column was updated with a 1990 or newer steering column with the air bag, the 1989 didnt have an air bag, so the wires must be crossed somewhere because of the different years,there was no air bag in 1989. I even tried a different turn signal switch today, that didnt help. the wiring in the car seems to be fine, might be better off changing back to the original steering wheel and turn signal switch?

 

You sure those are the stock gauges? Or have they been replaced recently?

 

the gauges are stock,just different year steering wheel and turn signal switch, i think the wiring is different in the 89, compared to the 90-93 with air bag

 

I'm fairly certain your turn signal isn't the problem. I think you may have a bad ground or power wire. Possible you may have knocked a wire loose?

 

i cant remember if the 89 had a 140 speedo or not, that may be where its at, i think the dummy lights are mounted in a different spot in the 89?

 

Where is your low fuel warning light, on in with the instrument cluster or on the bottom right of the plastic piece that the headlight/hazard switches are attached to

 

well the dummy lights are all in the center of the instrument panel, but the plastic housing surrounding the panel has them in the bottom right corner, i see you have an 89, nice by the way, where are yours located?