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Discussion Starter #1
There is a switch between the map lights that says "Door" and "Off," where you set it to Door so your lights come on when you open the doors. It isn't working, unfortunately. I removed it today to see if the switch was dirty, and hit it with some contact cleaner. No change--still doesn't work.

This switch is mounted in an assembly called "Module Assembly, Ambient Light" by Honda, part number 39180-SEC-A31ZB. I can buy a new one, but it's about $350 at the discount Acura parts dealers ($500+ list price). Looking at the service manual, it contains the blue ambient LED lighting for the dash and a very simple logic circuit with a diode or two and a transistor. This assembly also contains the HomeLink circuitry, which is why it's expensive (and that's on a separate board).

I wonder if anyone has had the same failure, and if maybe those components inside failed. I almost suspect it's the transistor since it is a larger transistor casing (looked similar to a TO220 case) and transistors of that size are generally used in higher current applications, producing heat. And this transistor is not on a heat sink.

It's not a huge deal to fix this but still, it should be working, and it's not. Curious if anyone else has experienced this.
 

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Never experienced this issue, sorry. I wouldn't think that the transistor went bad due to high current if it is a low voltage circuit. The diodes also may not do more than voltage regulation or to prevent reverse voltage leakage. If you can identify the diodes or transistor then I say go for it and try replacing those components. Hopefully they don't have proprietary markings to prevent them being identified by anyone other than the manufacturer. I hate when that happens. Best of luck.
 

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Discussion Starter #3
One reason I suspect the transistor is because I've seen cases where the transistor was designed just within the spec needed. In other words, repeated usage at or near capacity cause it to overheat and fail. (Not just in automotive, but in home electronics as well...at least back when we used discrete components and not SMDs.) In fact, wasn't the failed lighting in the TSX radio caused by a failed transistor on the board?

I agree--the diodes are probably there to prevent voltage leakage, although looking at the two back-to-back diodes, those may be Zener diodes (notice the slight "ticks" at the ends of the straight bars in the diode symbol).

Heck, even reflowing the solder sometimes fixes circuitry problems.

I think I might try this the next time I have the car. No doubt the transistor was an off-the-shelf part, and if it's no longer available, there are thousands to choose from that would have acceptable specs to replace it. Fingers crossed the part numbers are not obscured or removed. The schematic for the lighting control portion of this assembly:

47346
 

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It is strange that both lights are not working when you open the doors.
Do the map lights work when you press them?

It is common for 1 of the map lights to fail when a door is opened.
In that case, its the push button switch under the map light lens that is failing.
It is possible that both map light switches are failing.


This thread talks about the failing map light switches including a no cost fix:

 

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Discussion Starter #5
I forgot to mention it--both map lights work manually with no issues at all, and the switches appear to be fine. One of the two mounting screws for the entire map light assembly grounds it to the chassis and that is free of corrosion also.
 

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If both map lights are working manually, I would venture that both of those small switches are failing and not the map light circuit board.

Try cleaning the map light switch contacts as mentioned in the thread linked above.

Automatic TSX's are showing up in our local cheapo self-serve autowreckers here.
I would try a cheap used map light assembly or map light switches before buying anything new.
 

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There is a switch between the map lights that says "Door" and "Off," where you set it to Door so your lights come on when you open the doors. It isn't working, unfortunately. I removed it today to see if the switch was dirty, and hit it with some contact cleaner. No change--still doesn't work.

This switch is mounted in an assembly called "Module Assembly, Ambient Light" by Honda, part number 39180-SEC-A31ZB. I can buy a new one, but it's about $350 at the discount Acura parts dealers ($500+ list price). Looking at the service manual, it contains the blue ambient LED lighting for the dash and a very simple logic circuit with a diode or two and a transistor. This assembly also contains the HomeLink circuitry, which is why it's expensive (and that's on a separate board).

I wonder if anyone has had the same failure, and if maybe those components inside failed. I almost suspect it's the transistor since it is a larger transistor casing (looked similar to a TO220 case) and transistors of that size are generally used in higher current applications, producing heat. And this transistor is not on a heat sink.

It's not a huge deal to fix this but still, it should be working, and it's not. Curious if anyone else has experienced this.
Greetings,
I have a 2009 TSX with a similar but not quite the same condition. Some time back my map lights started to behave like the bulbs were bad or suffering from poor connections. After all the usual troubleshooting paths were exhausted, including bulb replacement and removal and inspection of the entire Module Assy, things got worse. Now the door light switch seems to be permanently closed (made) in the "on" position which is not the worst condition, but the map lights still don't work at all and now the HomeLink feature is inoperative. I believe there is some sort of power interruption within the Module, but at a loss as to confirm that short of buying a replacement Module. Then, what if that that doesn't resolve the the problem? I reached out to an online salvage part site with an inquiry, but never got a reply.
Any ideas out there?
Marjolug
 
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