so i'm getting battery and brake light when cold start for about 5 min..
then lights vanishing then for a while ABS light appears then disappear....
i did measurement:
start engine -12,03 V
3-5 min later magically 14,30V ?
i replaced alternator maybe 2 months ago, i made belt very tight so i don't think it can slip,

my suspicion
1)i messed up alt connector little bit (2 wires) but it was fitting tight anyway...
2)can belt be too tight or something?
3)could it be because bad groundings? so far i only cleaned battery negative to frame to engine...


any ideas?

 

Ya,clean all cables.pos,ground,ect.

 

Check the harness at alternator. When you first start the car, do your belts make noise?

 

no noise at all, i looked at alt and it is rotating too

what that harness actually do? telling actual voltage to ECU?

 

The altenator probably has a sticking brush in it that finally makes contact when it warns up a little.

 

it'll be last think to check, dont wanna take it apart , i got warranty.


i cleaned battery connectors, checked belts with no luck...
also have problem with locate OEM grounds other than battery (-) to engine and one next to washer fluid container. All search result is about installing aftermarket ground kits, but how about clean oem ones? where they are?


would it be electric short somewhere? what device is running only when car is cold and only for a while?? wouldn't it make sense?

 

I think you will not solve this by checking the grounds, the altenator has a problem. So many of us have had problems with rebuilt starters and altenators.

 

looks like you were right, i changed to new alt and it is charging all the time ,