3G Alternator Upgrade Ford Mustang 1987 to 1993

i recently performed this upgrade on my 1987 ford mustang gt convertible. the whole process took 45min after i had purchased all the necessary parts to perform the upgrade. the problem with the third generation ford mustangs is the 2g alternator that puts out 75-85amp depending on which one you get. the problem starts when you use the heater or head lights at the same time. the alternator can not handle the output. i was experiencing this issue. i installed an aftermarket digital volt meter. at idle with no accessories i would have 14.1 down to 13.5 i know that most ford products like to have 13.8-14.4 to operate correctly. i had an opportunity to perform the upgrade while my car was getting prepped for paint. i know i should have taken of video of the process but i took a video after in which i describe the whole process. the hardest part was finding a long enough cable to reach from the passenger side of the engine to the driver side. i did some research online throw countless forums, blogs. what i found is everyone want me to use the 10 foot positive cable to hide it just like the factory. well i thought to myself i can get the longest cable i can find and make it work. some say its the lazy approach by in my case it works for me..lol if i did this for someone else i would use a longer cable or use to short cables with a fuse holder. lets get down to the parts required to perform the upgrade. PS you can also use the stock belt it will work no need for a longer belt



1. 3G alternator (Mercury Sables and Taurus 1995-00 will work, or just buy one for a 1994-1995 mustang 5.0) best tip is to go to a wreaking yard or picknpull n get a good used alternator they usually cost less then 50 that way vs new ones from 85-145. its your money but 9 times out of 10 most vehicles in the wreaking yard have brand new alternators on them common part to replace.
2. 72in negative battery cable or 10 foot positive cable (both will work) or 2 6ft positive cables
3. MEGA Fuse Part # MEG125
4. convoluted wiring loom (parts stores have them)
5. a fuse holder for the mega fuse
6. grinder or cut off wheel
7. a nut and bot for the top mounting location (the newer alternators are not threaded)
8. wire connector for the new style alternator
9. butt connector

here is a diagram of the 3g wiring

Lets assume you have all the required parts? here we go.

1. remove the serpentine belt
2. remove the top alternator belt
3. remove the bottom alternator bolt
4. disconnect the wiring from the back of the alternator
5. test fit the new slightly larger 3G alternator
6. you will notice the case of the alternator is bigger and will hit the alternator bracket. use a sharpe
to mark the aluminum bracket to notch it out so that the case of the alternator can clear.
7. use the diagram above to wire your new alternator
8. reinstall the alternator
9.the belt will be alittle tight but it will work without breaking
10. rout the positive cable over to the charging side of the solenoid.
11. undo the old charging cable.
12. bolt down the charging cable ( or as i did mount the maxi fuse to the solenoid then bolt the charging cable to the other side of the maxi fuse)
13. wrap the charging cable with the maxi fuse in black electrical tape plus convoluted wiring loom cover
14. start it up n verify the voltage is steady
15. put a load on the alternator to verify that the new alternator is keeping up.


here is my video i took afterwards