When I am running fan on high, high beams on, rear defrost, and wipers, plus brake lights, at idle the system struggles and voltage drops. Voltage drop test on negative side tested fine, on positive side I had a problem so I added a new line from alternator to battery which corrected the voltage drop, but I'm still having the same problem. Any ideas? I shouldn't have any trouble running everything I just described right? Brand new Mitsu alternator.
Electrical Drag
- Thread starter Salonika
- Start date
I performed the voltage drop test from the FSM. That helped me identify a problem with the positive side (between alternator and battery). I repaired that line and the voltage drop is gone, but I still lose power when all accessories are on as described in my first post. It is easily noticeable too. Lights dim, fan slows and wipers move slow. Not sure what to do next. My brake lights make dash lights dim so I was thinking about checking the grounds.
JohnnyBfromPeoria
I'm Getting Around To It
Overkill the size of the grounds, it's cheap and easy to try.
John B.
John B.
For negative voltage drop, I put one probe on the alternator body and the other on the battery negative. Little or no voltage was registered, meaning all of the grounds are conducting properly.
I run into this problem in the spring / summer mostly, when its raining and humid. I've got everything on in that case, and when I pull up to a stoplight, electrical system struggles. Sure, once I rev it up, everything is nice and bright. When I am moving, it is never an issue. I have been reading a lot around the web on this, and it sounds like it isn't uncommon on a lot of cars. My other two cars don't react at all when everything is on, they are a little newer though. I've done all the FSM diagnosis I can, and I am not seeing a problem with the system. I've read about the possibility of putting a smaller pulley on the alternator to boost output at idle RPM. Only about 100 rpm seems to make the difference. Maybe I could just adjust the idle up a little bit.
I run into this problem in the spring / summer mostly, when its raining and humid. I've got everything on in that case, and when I pull up to a stoplight, electrical system struggles. Sure, once I rev it up, everything is nice and bright. When I am moving, it is never an issue. I have been reading a lot around the web on this, and it sounds like it isn't uncommon on a lot of cars. My other two cars don't react at all when everything is on, they are a little newer though. I've done all the FSM diagnosis I can, and I am not seeing a problem with the system. I've read about the possibility of putting a smaller pulley on the alternator to boost output at idle RPM. Only about 100 rpm seems to make the difference. Maybe I could just adjust the idle up a little bit.