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Discussion Starter #1
Hey guys,

I didn't see another post with this same issue, but I apologize if this is a repeat - there are a lot of posts about interior lights, so please let me know if there's a better thread on this.

I just finished fixing my interior lights in my '07 Ody with ~225k so that they all come on and turn off automatically with the dash switch in the DOOR position. In summary, there were two issues: 1) corrosion inside each dome light switch and 2) poor contact between the dome light switches and the pins that go into them.

  • When opening a door, the dome light over the middle row on the passenger side turned on as expected and turned off 30 seconds after all doors were closed
  • The courtesy lights on the front doors worked as expected when opening the doors
  • The OFF and ON positions of the dash switch worked correctly
  • Every interior light could be turned on manually
  • Note: Since the ON and OFF positions worked correctly, all troubleshooting was done with the dash switch in the DOOR position

  • Each dome light (except for the front dome lights over the driver/passenger) has three wires
    • One wire is ground at all times (black with a stripe), another is hot at all times, and the third switches between 12V and ~0V (actually a handful of milivolts)
    • When a door is opened and the lights should be on, the third wire will have ~0V on it as controlled by the electronic control module
    • When the lights automatically turn off, that goes to 12V
      • This eliminates the voltage differential across the bulb so that power doesn't flow through it
  • Therefore, the wiring leading up to the dome lights was correct and the problem had to be in the dome lights themselves

  • Next, I unplugged the dome light assembly and ohmed across the contacts going to the push button
    • This is a single pole, double throw switch
    • The middle pin is the common terminal
  • There should be about 0.2 ohms between the middle pin and the one it is switched to, and OL (open) between the middle pin and the third pin
    • In my case, when the switch was switched to the auto position, the resistance would float in with hundreds to thousands of ohms
      • Since these lights lived most of their lives in that auto position, that position had significantly higher resistance because more current flowed through those contacts than the others
  • I removed the push button (it just pops right out with a little prying), sprayed DeOxIt into it, thoroughly exercised it, then blew it out with compressed air
    • That helped, but resistance was still in the ~5-10 ohm range
      • This was because, as is common with square sockets, the sockets had spread enough that not all the pins fit snugly into them
  • To resolve this, I gently bent each pin up a bit
    • This adds a little extra pressure between the pin and the socket
  • After those two steps, I had 0.2-0.3 ohms for both switch positions
    • I repeated this process for every dome light with the same results every time
Now, when I unlock the van or open a door, all the dome lights come on for a couple minutes, and when I close the doors, all lights stay on for 30 seconds.

Once I figured out what was going on, it was super quick and easy to fix all of them.

Hope this helps!

  • 1987 Mercedes 300SDL daily driver, ~402k+
  • 2007 Honda Odyssey EXL, ~225k+

12,968 Posts
At one point those switches were available at for extremely cheap. Not sure if they still are. I bought a couple and have them sitting in a box waiting for one to die.
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