Electrical Issue

[cbrracer]

I have a 99 Eclipse GST and after a while of driving lately at low rpms the voltage seems to be dropping until the car is almost dieing and the SRS light comes on. I can get the srs off and it to return to normal by revving the engine higher then 3.5K so that the alternator kicks in and puts the full ~15V at the battery.

If I drive revving the engine higher everything will be fine, but driving at under 2.5K after a while will cause it to go down as I suspect it is for whatever reason running straight off the battery.

I have replaced the battery and alternator. I have checked fuses, checked wiring and grounds and all connections seem ok. I'd rather not take it to a shop but it may end up going that route as I am getting tired of trying to fix the issue.

Any suggestions?

 

[TALONTRAX]

It doesn`t matter how new the alternator is, it still may be weak - get it tested. Also, not to sound dumb here, there is an alternator fuse in the box under the hood, make sure it`s good or it won`t charge at all . . .

 

[cbrracer]

This is my second replacement alternator so I wouldnt think it would be weak but I could get it tested. 100amp, I believe it was, fuse is good. Kind of at a loss since I even took out my dsmlink ecu and put the factory back in to make sure that was not the issue.

Strange that the car seems to move towards death when in low rpms, but alternator will kick in above the 3.5K range and bring everything back to life quickly and once run at lower rpm again will slowly move towards death again.

Hmmm

 

[TALONTRAX]

1 more thing . . . again not to be stupid - make sure the belt is adjusted correctly & not slipping - this will cause a low-rpm discharging condition -

A little side topic to this . . . just recently My charging system seems to be slightly OVER charging - like 15.0-15.3 volts sometimes - I wonder if the voltage regulator is going bad ?

 

[Butterfinger]

I went through 4 alt's straight from advance. I would start the car and unplug the negative cable to the battery and see if it stay's running. It should.
Definitely sound's like alt.

 

[TALONTRAX]

^^^^^ NEVER NEVER disconnect the battery while the car is running !!!! That might have been a good testing technique back in the 70`s before ecu`s & computers were around - do that on your car & you`ll have problems for sure. Just get the charging/electrical system checked to diagnose your problem . . .