after i got the fuel pump all taken care of i took the car for a spin. all of the lights inside and outside of the car dim when i hit the breaks. any ideas? the car has a rewire kit for the fuel pump and the battery was relocated to the rear. the car also has some "custom" wiring for the spal fans, tuning and what have you.

 

Check to make shure the alternator is charging correctly. Did you use all the correct gauge wiring to relocate the battery and are all your grounds hook up properly and to good solid grounds ie the frame itself? I see this in my customers cars all the time with Mustangs with batteries in the trunk. They use too small of wires or they have poor ground connections which both will fuck with the electrical system of the car.

 

if you have a turbo timer or volt meter it should be running between 13 ish volts and 14 at idle. if its below 12 theres a good chance the alternator is going bad. oh also if the volts dont rise when the motor is at anything higher than idle than the alternator is said cya.. If thats not the case then you have a short somewhere or corrosion on a critical batter cable that is causing a not enough power to be supplied from the battery. oh yes bad grounds as well will do it.