Alternator controlled by ecu on 2g?

[spyderman1997]

thats what i have read in a few forums but i was wondering how the ecu regulates the alternator? if anyone knows how to test that and if it can make it seem like i have a bad alt? i do not have a bad alt or battery or connections. triple checked and cleaned it all. please help its starting to get worse!

 

[gma0408]

Whats the problem? Have you checked the grounds?...done a voltage drop test to them?

There is a 4 wire plug on the front of the alternator. The green and white go directly to the ecu...pin 33 and 41 The black goes to the generator relay then on to the tail lights. The red goes to the 40A fuse.

 

[luv2rallye]

The black goes to the generator relay then on to the tail lights.

No it goes to the generator relay and also to the battery and brake warning lights on the dash.

[gma0408: I think I wasn't clear replying to your post when I told you it goes to the brake light. I meant the brake warning light on the dash. Since I said it also goes to the battery light (which is on the dash) I assumed you knew I meant the dash brake warning light when I just said brake light - sorry].

 

[luv2rallye]

thats what i have read in a few forums but i was wondering how the ecu regulates the alternator? if anyone knows how to test that and if it can make it seem like i have a bad alt? i do not have a bad alt or battery or connections. triple checked and cleaned it all. please help its starting to get worse!

The alt has it's own internal regulator. The 2 ECU wires are for voltage sensing to control the IAC and the other is a control to disable alt output under certain heavy load conditions.
Make sure the battery and brake dash warning lights work (or the generator relay) or the alt won't put out (they provide alt field coil startup current).
To test alt: http://www.dsmtuners.com/forums/pro...reeway-electrical-problems.html#post151165661

 

[spyderman1997]

yea those lights come on and sometimes the srs. i have used 2 diff alts which bench tested good off the car and two diff batteries that have been fully charged and tested off the car. if the car sits for a while it will charge but after about 5 mins it seems it stops. if the ecu is bad can it make it so the alt wont be able to get a good charge to the battery? i have cleaned grounds and connections on the battery. both alts on the car put out around 11-12 volts while running. during the test the amps were really low, is that an indication of a bad alt that cant be detected on autozone testers?

 

[luv2rallye]

The alt should put out over 14V. and over 50A. when bench tested. On the car a battery with a shorted cell or a short can pull the voltage below 12V which can mislead you into thinking the alt is bad. Normally a car should have around 14.3V at the battery when engine is running and everything else is ok. Make sure you have large negative cables going to both to the body and the starter mounting bolt. Also make sure the 100A fuse is ok. If the ECU (or a short) grounds the white wire on the alt's 4 wire plug, the alt's output voltage will not go over 12.5V (you might want to measure this). Here's how you can test the alt and battery yourself: http://www.dsmtuners.com/forums/pro...reeway-electrical-problems.html#post151165661.