Uncourteous courtesy lights

[jyanno]

The Mrs. couldn't start the '04 XC70 on Thursday. Replaced old battery on Friday was able to start/drive car around with no problems. Couldn't start car today. I noticed that the courtesy lights (the driver/passenger floor lights) were not shutting off. I pulled the bulbs, jump started the car, drove around a bit and was able to start the car. Going to see if she starts tomorrow.

If it is just the courtesy lights draining the battery. Is there a DIY quick fix for this? Any ideas where to start? All the doors were closed but the lights were still on after 20 min.

[kamiar]

try to lock-unlock with the remote 2-3 times, open the hood and lift gate and shut them a little hard, also all the 4 doors and check the lights...

[jyanno]

Thanks, that fixed the courtesy lights, but the battery died again a couple of weeks later. Then one day we noticed the cabin blower wouldn't stop. Guess that was probably the drain that caused the battery to die in the first place.

[kamiar]

Well the cabin blower sometimes keep working even with engine off to maintain the air quality in the cabin, wait for 30 minutes and check back if it is still running, then there is a problem...

What battery you have now?

[jyanno]

I have a MY04, i replaced the original battery with a new one that I picked one up at Napa. It is an exact fit. The blower was stuck on full blast for hours after the car was shutoff. I had to pull the fuse to stop it. I had the cabin blower and the controller replaced.

[Willy]

If I am not mistaken, the power transistor that controls the fan speed sometimes fails.
The cause may be that the cabin air filter is not replaced in time, making the fan work harder to pull the air in.
This makes the transistor run hotter and receive less cooling, possibly leading to a failure.
If it fails into a short circuit, the fan will run at full speed as the current is no longer restricted.
Willy