very strange electical problem

[dsminburgh]

ok heres whats goin on sometimes car starts fine but sometimes you turn the key and it has no power or it has very little and weird things happen like alarm goes off but not as loud as normal if you jump the car it starts right up and runs fine the battery is brand new also there is a noise coming through the speakers that rises with rpm but that doesnt start until i take off the jumper cables if i touch the cables back to the battery it stops but if i take them off it starts again i dont know whats goin on but i can coast start it also and if the radio is off it wont make the noise either its a 91 talon tsi with the factory alarm

 

[LunarEclips]

the "whining" noise is from your stereo system, not your battery. Im guessing you have an aftermarket amp for your speakers or a subwoofer? The rca signal is near the power wire or you need to find a new ground for the radio or amp.

as far as your battery not staying charged, it sounds like your altenator is bad. The could also be another reason for your "whining"

 

[Dasamary]

Sounds like your battery is bad or the terminals are gunked up causing a bad connection. In addition if your alternator is going bad it might not be charging the battery correctly. It might supply a little bit of power and if you drive for 2 hours it will charge the batter but a 15 min run won't do much.

Look at the terminals on the battery and see if they are dirty. Have your battery tested; most car shops will do it for free. If both of those are ok; its probably the alternator...if you have done any rewires...they could cause an issue as well.

 

[dsminburgh]

my battery is new i did not think it would be the alternator becuase everything else is charging while the car is running all lights and gauges but i do have a amp for subs and when it makes the noise the radio will shut off and reset periodictly but i will check the rca thanks for the suggestions

 

[LunarEclips]

have your alternator checked at autozone... its easy and free!

 

[toybreaker]

A failing/failed alternator diode can cause both the low/no charge, and the noise symptoms.

This may/may not show on the go/no go alt. test at a chain store.

My recommendation is to have it checked at a reputable local electrical rebuilder.
They will check for a/c ripple/diode health and many other parameters that the go/no go won't catch.

There's a series of straps/bus bars inside the alternator. For whatever reason they seem to burn away (WTF ) around the diodes on cheapy remans...It's almost a pattern failure on the chain store flavor remans... ...(cool new gliffadingus!!!)

There's bound to be a reputable rebuilder in your area. My suggestion would be to ask to see the regulator package he uses on his rebuilds. If he is using quality stuff, he will be more than happy to show you his parts and product. Most of the local guys take real pride in their product, and they will be there to help you solve any potential problems that arise further down the road. Sure it costs more to buy from them, but the same guy will be there for you when there's an issue down the road, and he WILL remember you...and will be a significantly better resource than a chain store **** employee...

And it is a dsm,
so,
there will be issues down the road.

As a side note, there is a 90 amp upgrade for the factory 75 amp alternators. It was an o.e fitment on the candian cars and the Galantvr4's. If you're running a powerfull stereo, it's a nice upgrade.

 

[dsminburgh]

thanks for the info toybreaker