Today I was checking the under-dash fuse box in my 2008 TL-S for a particular issue:
rainy days ==> alarm went off suddenly ==> MID showing Rear Left Passenger “Door Open” when it is closed ==> cannot lock
car with key fob since car thinks door is open)

https://acurazine.com/forums/3g-tl-problems-fixes-114/raining-my-tls-freaking-out-889340/

Since there are already a few threads regarding this issue possibly being caused by faulty door switches, rain leaking through the moonroof drain and onto the MICU, etc., I won’t go into too much detail here.

(I did do a bit of trial and error, such as swapping door switches, but to no avail; the switch location in question seems to intermittently work, so not sure if it’s a loose connection or something else)

So back on topic: I decided to check the fuse box, and noticed that the #5 fuse had some slight discoloration, and the top was slightly bulging:






According to the service manual and fuse box cover, the #5 fuse controls the audio system.

I pulled the fuse, and other than the discoloration and bulge on top, it did not seem to be broken. And I don’t have have issues with the audio system; this car’s ELS system is one of the best I’ve experienced in any vehicle, and music plays clean and strong.

Is this fuse bad? And if so, could leaving a fuse in this condition possibly affect the other fuses and/or cause electrical problems? (such as the problem described earlier)

Any advice would be greatly appreciated. Thanks!

 

Looks like an indicating fuse? Note the surface mount LED and resistor just under the surface when viewed from above. The bulge is just extra space for those components.

 

For your door issue:

when the car detects that door switch is grounded, it's thinking the car door is open. There is a wiring issue between that door switch and MICU if you've swapped the rear left and rear right sensors and it stays with the same door.

 

I thought it was strange the fuse looks a different than the others, which all have a flat top. Those dark spots aren't melted metal?

 

That looks like a smart fuse with an LED built in. Feel free to replace it with a regular 20 amp fuse, it shouldn't make a difference. When the fuse blows, the light should turn on/LED. Dark spots look like solder

 

Thanks for the reply! And sorry for dragging the issue into a new thread.

I've never had this issue before in the past, so it's baffling me. Other threads often stated that it happened when it was raining, so I'm not sure if it is just a coincidence with all the rain we are getting right now in Southern California.

Door open" shows only when I put the key into the II position; once I start the car, it goes away. But I can tell the problem is there when I turn the key off and into the II position again, and the auto unlock function doesn't work (and all the doors stay locked).

When I swapped the switches, it seemed fix the issue at first; the MID would show the door as closed when pushing the door switch, and even the auto unlock function was working.

But I didn't trust it to stay fixed, and indeed after a few minutes the car started showing "DOOR OPEN" again, and strangely the switch would work intermittently: pushing the switch all the way in would still show OPEN, but pushing it halfway would be closed. Then it stopped working completely.

Does the ground connection have anything to do with the screw holding the switch in place? There's a washer on the body of the car which seems to match up with the end of the screw. (also when removing the screw I also noticed metal shavings attached which probably came from the threads rubbing the body of the car)

Could it be a problem with a fuse which controls the door locks? I was looking at the service manual for one, but couldn't find it.

 

You're both right; I found pictures of similar fuses online. Thanks, learned something new today!

 

Nevermind, it shows on the fuse cover as #8. That one seems to be fine.






Strangely enough, the switch started to work again, as I can now lock the doors with the key fob. But I’ll know sooner enough whether it stays functioning if my alarm goes blaring in the middle of the night.