Electrical Issue please help!

[krarks]

Ok so just finished up doing the 130A (3G) alternator swap, following the instructions on here (upgraded wiring, fused) and it worked great!

The whole reason for doing the upgrade is that the sub and amp were causing the dash lights, headlights, and battery to get demolished because the 75 amp one just wasn't enough power. Problem is, is that this problem still exists even with the new alternator. With the sound system turned off or down, the system reads 14.6-15V at idle and the headlights flicker a little, dash lights are ok.

With the sound system cranked, the dash lights flicker like crazy and so do the head lights. The voltmeter reads at around 12-13V too. The sound system never cuts out though. I'm starting to think something like a bad ground but I'm not sure. Don't know a whole lot about Mustang electrical. Also, this sound system was put in by the previous owner so I have no idea what has been done.

Some suggestions will help greatly guys. Thanks!

 

[bubba-dough]

Make sure all of your connections (stereo equipment, battery, 3g, etc) are good. Make sure that all of the wiring is the correct size for distance and current (amperage) being used. What kind of amperage is the stereo equipment pulling? You could be still pulling more current than your 3g (assuming the alternator is good) can keep up with especially while headlights and such are on. 130A alternator is only 130A above a certain rpm. You may look into a capacitor to help out if this is the case.

 

[HISSIN50]

Agreed about ensuring the battery cables, engine grounds and battery itself are up to par and upgraded for your alternator upgrade.

You could overdrive the alternator if the issue persists.

 

[ID89GT]

I wouldn't get a capacitor, there a waist of money imo. All they are is a band aid to another problem, such as a weak charging system, but if you just did the 3g then your problem is elsewhere.

 

[95Vert383AOD]

How big is the stereo??? How much is the stereo drawing? More importantly what amps(s)

 

[bubba-dough]

I wouldn't get a capacitor, there a waist of money imo. All they are is a band aid to another problem, such as a weak charging system, but if you just did the 3g then your problem is elsewhere.

True the charging system could be upgraded more if you wanted and if this ends up being the case, but caps are not a band-aid. They are suppose to be used for instances like this, voltage storage, along with isolating parts of a circuit, or filtering, or voltage multiplier, or etc.... I guess what I am saying is that with a cap you are using a legitimate electronic component for a legitimate electronic use...you are not "jery-rigging".

 

[jrichker]

Any car that has a 3G or high output current alternator needs
a 4 gauge ground wire running from the block to the chassis
ground where the battery pigtail ground connects.
The 3G has a 130 amp capacity, so you wire the power side
with 4 gauge wire. It stands to reason that the ground side
handles just a much current, so it needs to be 4 gauge too.

The picture shows the common ground point for the battery & extra 3G
alternator ground wire as described above in paragraph 2. A screwdriver
points to the bolt that is the common ground point.
The battery common ground is a 10 gauge pigtail with the computer ground
attached to it.

Picture courtesy timewarped1972

 

[SMOKEDYA]

Any car that has a 3G or high output current alternator needs
a 4 gauge ground wire running from the block to the chassis
ground where the battery pigtail ground connects.
The 3G has a 130 amp capacity, so you wire the power side
with 4 gauge wire. It stands to reason that the ground side
handles just a much current, so it needs to be 4 gauge too.

The picture shows the common ground point for the battery & extra 3G
alternator ground wire as described above in paragraph 2. A screwdriver
points to the bolt that is the common ground point.
The battery common ground is a 10 gauge pigtail with the computer ground
attached to it.

Picture courtesy timewarped1972

so are you saying run a ground from the block to anywhere on the chassis for an extra ground because of the 3g? peace



john

 

[jrichker]

so are you saying run a ground from the block to anywhere on the chassis for an extra ground because of the 3g? peace



john

Yes. The best place is the body ground being pointed to by the screwdriver.

 

[ID89GT]

Yes. The best place is the body ground being pointed to by the screwdriver.

Would it be easiest to just run one right off where the starter ground is to the chassis? That would seem the easiest way

 

[SMOKEDYA]

what about putting it on the firewall(tranny tunnel area) or on the frame rail by the sway bar mount? i only ask these spots cause i did all my wire hiding and it would stick out like a sore thumb. peace


john

 

[krarks]

Ok it's a 1000W amp with 2 12" subs. There is a capacitor wired into the system. I should mention that this isn't my mustang but my friends. I am just the lucky guy who gets to work on it. The wiring of the stereo and amp were done by Best Buy and Visions Electronics.

The ground was already upgraded before the alternator went in. I'm thinking that maybe the battery is weak and perhaps the capacitor that is wired into the system isn't working or just isn't strong enough. I will have more answers this weekend for you guys.