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Discussion Starter · #1 ·
Hi all, its been a year since I purchased my 2004 Mazda 3 and it has been great! Just recently there has been a ghost in the car or something!

It seems that my interior lights stay on while im driving.

If you get into the car, close the door, and start up the car the interior lights stay on for 5 minutes. But if you open and close ANY door the lights will then shut off.

If you get into the car start up the car, and then close the door the lights shut off. Also sometimes when you do this method, the door locks just start going nuts locking and unlocking very quickly.

Edit - Also the when you use the key fob to lock the car at night the interior lights stay on as well.

Has this been a common problem, does anyone know what could be causing this?

Thank you in advance for your help everyone.
 

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The door locks will do that when you try to lock the doors while a door is ajar. Is your door open warning light on? You might have a sticky switch.
 

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My '04 is having the same problem with the lights but no trouble with the locks. Has any one had an issue with the driver side door switch causing this?
 

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Discussion Starter · #4 ·
UPDATE --

Dealer finally found the fix.

Its the main junction box? Something like that. Its basically like the main computer. Repair is $1400. Glad I have the extended warranty.
 

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Hi there

This is my first post and I'm currently experiencing the EXACT same problem as above!

We've replaced the BCM (Body control module) which cost $2000 which fixed the problem for 2 hours and it has returned.

I've read above that it was the main junction box? Is this referring to the BCM or something else?

Anybodys help would be greatly appreciated.

Many thanks,
 

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[quote author=tknova link=topic=135993.msg4039430#msg4039430 date=1307051449]
Hi there

This is my first post and I'm currently experiencing the EXACT same problem as above!

We've replaced the BCM (Body control module) which cost $2000 which fixed the problem for 2 hours and it has returned.

I've read above that it was the main junction box? Is this referring to the BCM or something else?

Anybodys help would be greatly appreciated.

Many thanks,
[/quote]

The "main junction box" or "body control module" is what a lot of people refer to as the "fusebox under the glove compartment". Mazda's name for it is "Passenger Junction Box", or PJB. It is in fact the computer that that manages most of the lighting, door locks, etc. as well as holding the fuses.

Electrical troubleshooting can be downright nasty, especially when the problem is intermittent. It mostly boils down to spending a lot of time with a multimeter checking for open circuits, short circuits and abnormal voltage drops. It does help to have an understanding of why things occur. For example, you can consider: The PJB unlocks the doors when "............" And then go from there. In this case the answers include "door switch pressed", "key in door turned", "remote button pressed", and "key in ignition". So if it were me, those are things I would start with.
 

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Thanks for the clarification, well. We changed the BCM as this was the reported problem with the interior lights and central locking issue. After I got the vehicle back, it was fine until later that night I went to go and get fuel and the same issues returned.

This worries me, I think the new BCM has blown up again already giving me the same problems again :(
 

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[quote author=tknova link=topic=135993.msg4039734#msg4039734 date=1307085789]
Thanks for the clarification, well. We changed the BCM as this was the reported problem with the interior lights and central locking issue. After I got the vehicle back, it was fine until later that night I went to go and get fuel and the same issues returned.

This worries me, I think the new BCM has blown up again already giving me the same problems again :(
[/quote]

Take it back to where you got it fixed? I'm sure there is some inherent 24-hour warranty. Otherwise, it would seem like they gave the car back without fixing the problem (and charging you all that money for nothing).

If you want to do it yourself, a first step you could do might be to visit a salvage yard and try pulling the BCM from a junked car. Most salvage yards are an awesome way to get parts for cheap-ish.

If it's still acting up, you might have a short somewhere (which could be causing the BCM to blow). Not sure how the BCM is wired, but if there's no fuse (or an improper fuse) in-line before going to it, then a shorted wire upstream could result in the BCM getting blown.

As stated above, electrical trouble shooting is a royal pain in the ass. I had a fuse that wouldn't stop blowing in my old F150. This fuse was connected to the brake lights, turn signals, and cruise control (oddly enough). Went and bought a 20-pack of the 20-amp mini fuses for $8 from AutoZone. I noticed that the fuses blew (MOST of the time, but not all of the time) when I shut the driver's door. Long story short (after a lot of blown fuses), found that a wire in the driver's door had rubbed through its sheathing and was grounding itself on the metal of the door. Patched the wire and haven't have troubles since!
 
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