Does this sound like an alternator issue?

[Workman1788]

This has happened a few brief times since I got the car a couple months ago but tonight was really annoying me. Occasionally, while driving at night, all of my lights get brighter and the heater dies. Then, it will go back to normal for a while, then shortly after, everything's bright again and no heat. The alternator seems to be overcharging to me but no warning lights come on. Anyone else ever experienced this and know a possible solution before I start throwing money at the problem. According to a battery tester I used, the battery is good and alternator is producing 14.1-14.6 volts while running but i never could get it to act up with the tester hooked up.

 

[Lownslowlsc]

Just throwing it out there... since the blower requires a decent amount of power perhaps the plug(known problem) for the blower motor loses its connection thus making the lights brighter.

Does it do it when the heaters not on?

Try wiggleing the blower motor harness(behind glovebox) with the heat on and check to see it they brighten.

Thats the only thing i can think of.

 

[chris2523]

yeah, good idea.
check this write up.

Lincoln Mark VIII Intermittant Blower Motor Repair

 

[Workman1788]

i'll give it a shot tomorrow. yeah only does it with the heat and lights on at the same time but only while driving.

 

[Workman1788]

Alright, I tried messing with the wires for the blower motor and couldn't get anything to happen. My blower motor doesn't have a plug on it like shown in the write-up, possibly aftermarket. The wires run into a hole in the blower motor and somebody has already done something with them. The orange and black wires had been cut at some point and taped back together. I replaced the tape with some nifty butt connectors I had that have solder in them. So that should be a fix to that if it was the problem. I may go for a drive tonight just to see if it's still acting up, then I'll report back.

 

[Lownslowlsc]

Its prob a universal aftermarket blower. Hopefully since you soldered and made a better connection it clears things up. If your alts testing above 13.8v and batteries above 12v i dont think thats the problem..

 

[Workman1788]

after driving for about an hour and half last night, the problem made its return. It only did it for about 30 seconds this time but the "check charging system" did flash on for a brief second. When I fixed the wires for the blower motor, I had also cleaned the plug for the alternator. I did notice that the plug wasn't snapping on like it should and it fit a little loose. I pinched the prongs together a little so that it fit tighter. If the rain ever stops, I'm going to try messing with that plug to see if I can replicate the problem.