Headlights and interior lights get brighter, with voltage drop?

[jeepocabra]

Noticed this the other night in my 1991. If I pull up on the window switch while the windows are closed(checking too see if they are all the way up), all my lights in the vehicle get brighter. However the voltage drops. Does anyone else get this? or have I got something wrong?

 

[jeepocabra]

Im still having this happen. Anyone?

 

[Ebag333]

Have you checked your battery and alternator to make sure they are within spec?

 

[jeepocabra]

I know the batterie is in spec. Not sure about the alternator, Ill have to pull out the FSM and see how to check it.

 

[Ebag333]

Do your RPM's change when you hit the switch (or shortly after)?

 

[jeepocabra]

nope no change in rpm's.

 

[Ebag333]

Hmm, I'm out of ideas then.

I'd start running the various FSM electrical test and see if anything is out of spec. Maybe a relay or something is failing?

 

[Lka1988]

Mine does it too. Both batteries are good and the OEM alternator is less than two years old.

I just chalked it up as one of the typical quirks of an early 80.