MH_Alex

As in the title looking for any help diagnosing this problem on my 04 manual transmission. Ive tried testing under several different conditions and it seems that the issue does not depend on the ambient temperature or whether the A/C is on. The condition to replicate is slow increase to high RPM (5-7k) followed by lightly lifting off the gas pedal. The lights will come on and stay until i let the rpm fall back down to ~3k. If I proceed to stomp on the gas after the lights come on, they will continue to stay on (again until the rpms are allowed to fall back down) and the car will drive just as expected: no loss of power. The one interesting condition during this sequence is that as the lights come on, the cabin fan speed will sharply increase up to the same speed that they run at with key on and engine off (not sure if this is normal but definitely true for my car). Car has a "new" rebuilt alternator from so I don't think it has anything to do with battery voltage. This problem emerged a couple months ago with no obvious changes that can explain it. The only service I can remember is doing the water pump and thermostat. Thanks in advance!