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1998 Mazda B4000 dome light and key bell don’t work

I have a 98 B-400 Mazda pickup truck. The dome light and warning bell for headlights and keys in the ignition do not work most of the time. From what I remember this started at the same time a clicking sound came from behind the radio when any one of these lights and bells would malfunction. Anyone have an answer!!!

Sounds like a broken wire. The clicking noise might have been the wire reconnecting then separating again. Going to take some detective work with a multimeter.

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Likely a device behind the radio that makes the sound… or the radio itself makes the sound… is broken. Given that this is a 22 year old truck, parts may no longer be available. Or as @Purebred posted, a broken wire. Finding and fixing this could be difficult and expensive. Is the truck worth this?

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If you use a circuit diagram you can find the wire or connector or ground that those devices have in common.

I feel somewhat certain that the GEM module is involved in this problem. And diagnosing the actual failed piece can be a nightmare. But the door switches (in the latches) that turn on the dome light and set off the bell are notorious for failing and running the battery dead.

My first check would be to make sure the driver’s door switch is making a good ground connection when the door is open. If that is okay then make sure that wire connection is okay to the circuit it is tied to.

This is a total guess… but it was around the late 90’s when mfg’s started incorporating other subsystems within the head unit. An example of this would be the 97-98 Honda Civic…that had the power door lock module inside the factory radio…remove radio and no power locks anymore…

Maybe some of this sort of witchcraft is afoot in this vehicle as well? Completely guessing…but letting you know its possible. Its not a logical thought that your radio has door lock wires running into it…so…of course you dont suspect that.

Back in the day…to install a new radio into a Civic with power locks…you would leave the factory radio plugged in…and then stuff it up into the dash. Then wire up a new Alpine or Kenwood etc… Silly no? True story.

Ford Ranger, but should be basically the same truck. It’s behind the radio and this video hopefully helps narrow it down.

Thank You I will put that info. to use.

Thank You I will try this.

Yes the truck is worth it. Good body and runs great. Better than a new 35.000$ truck. If it put 1500 a year into the truck I’m ahead.
Thanks for the info.


Thank You Yes they we’re made on the same line in jersey. I will try putting your info. to use.


Dan , not that is really important but just incase you don’t know . It is not necessary to reply to each post as all posts are seen by everyone . That way you can put all of your thoughts in one post.


The troubles you are having are all related to the door switch. If that wiring is broken inside the door jam that will cause the trouble. The switch makes a connection to ground when the door is opened. I suspect that wire has broken inside the door jam due to stresses on it over the years. It is a common problem with wires going to the door.

Mr @Cougar makes an excellent point… one that I am shocked I didn’t suggest myself… Duh…man some days I tell ya… The lights are on but no one is home sometimes.

I’d check the door switch first n foremost…now that I am awake.

That happened to a ground in my Civic. It caused the window motor to not work. I never found the location of the bad ground, but ran a wire to a bolt inside the door cavity and that fixed the problem.

[quote="Honda_Blackbird,…now that I am awake.
Prove’s the need for a AM cafeen fix.

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The operative problem being that it was late…not early. I wake up around 5 and posted that in the afternoon.

If I drank caffeine you guys would dislike me more than you do already @Renegade

I tried spraying white lithium grease on the locks and that didn’t work. The problem is the same on both doors, so I don’t know how likely both grounds would have broken off at the same time.
This is the door ajar light ,dome light and key in ignition bell not working. so I suppose the next thing is exploring behind the radio for the relay.

OK… Lets back up a few steps… does this B4000 even have door jamb pin switches? I think it doesn’t by 98’ so that means the door ajar…or door closed switch is internal to the latch inside the door.

Personally… I would simply probe that wire to see what it is doing… then I would actuate the door latch with a phillips screwdriver shank…and see what the wire is doing… It should be a make or break type connection in the latch switch… You just need to know what wire handles this function. There are Alarm system wire charts that tell you what every wire does and what color it is… This can save you a ton of time chasing physical mechanisms etc…as you dont need to actually interface with the latch inside the door when you are reading its wire state… Savvy?