Alternator plug testing question

[fastasseclips95]

Can anyone point me to where I need to be to learn how to test the plug that goes to the alternator or tell me how. I have a brand new alternator and battery but I am still having problems with not getting enough charge to start the car after I drive the car for around 8 miles around city streets. Any help is greatly appreciated so I can start tuning and having fun with my car. Thanks this is on my 99 gst by the way

 

[rlacasse1]

Have you checked the 80amp alternator fuse in the fuse box.

 

[fastasseclips95]

Yes the fuse is good, thats why I think its something with the wires or I somehow got a new bad alternator.

 

[90moneypit]

There's something wrong with your 'new' battery. You should be able to drive a lot farther than 8 miles on a fully charged battery even if the alternator wasn't charging at all. Now that being said, if you don't have a fully charged battery when you install a new alternator it will suffer alternator death and not charge. I don't know if it's the resistor, rectifier, or regulator that gets burned out but it keeps the alternator from properly working after that first start-up. Have that new battery checked for a bad cell before replacing that alternator. I've learned that the hard/expensive way than once so I always check the battery first. $80 battery vs $250 alternator... not to mention the time involved running to parts store and replacing the part.

 

[Codester]

I'm having the same exact problem. I checked the wire colors and my wires are not in the same order as the factory service manual. It's only charging at 12.2 volts and the FSM said that the G terminal might be grounded at the ECU which sucks ### I have no clue where to start

 

[DSM1G90]

Get a DC voltmeter, or a VOM and with the car running in idle, touch the leads across the battery and observe the polarity as well.

Alternator should be shoving out 13.5 to 13.8VDC during any RPM with all access and lights off. Any differences, usually a bad alternator is the culprit.

 

[fastasseclips95]

I tested my alternator with the car running and im only getting 11.5 vdc. Thats why I want to know how to test the plug so I can trace it down to being a bad alternator or a bad wire.

 

[Got Boooost]

were you able to find out how to test the plug? Im in the same boat right now, Im looking to find out how to test the plug.
thanks

 

[luv2rallye]

It's only charging at 12.2 volts and the FSM said that the G terminal might be grounded at the ECU which sucks ### I have no clue where to start

Measure the voltage on the G terminal. If near zero, you either have that wire grounded or the ECU is grounding it. When that terminal is grounded (by the ECU normally) the stock 2g alt is designed to output 12.5v max. This is used during heavy acceleration to keep the alt from loading down the engine so more power is available to the drivetrain.

 

[luv2rallye]

2g alt and battery test on the car: http://www.dsmtuners.com/forums/new...reeway-electrical-problems.html#post151165661

Another source (besides a weak battery) of a perfectly good alt not charging on a 2g is a burned out dash charge light AND the generator relay (which is not really a relay) not functioning - one of the 2 must work for alt to work. The generator relay seems to get easily physically destroyed for some reason on 2g's (and missing on some 99's). It's next to the turbo wastegate solenoid.