I have a 1996 acura rl my interior courtesy lights stopped working I dont know why. I have even changed all the bulbs. Also I have to set my dome light switch to the off position (far left switch setting) or my dome lights will stay on. When i switch the dome light to door (middle switch setting) my dome lights will continue to stay on even after all the doors are closed.

 

It's nice to see that someone has the exact same problem that I do. I purchased a used 1996 RL for my son about 6 months ago. Ever since we bought it, the courtesy lights do not turn on and interior dome lights stay on all the time when you open and close the doors. (We leave the interior dome light switch in the OFF position.)

Looking at the schematics, I think the problem is with the Passenger's Multiplex Control Unit. The courtesy lights connect to the Passenger's MCU at Connector B, pin 21 (which probably never gets grounded). The dome lights connect to the Passenger's MCU at Connector B, pin 10 (which is probably grounded all the time).

I might have to take the car to the dealer and see what they can figure out. I hope a new Passenger MCU is not too expensive!

 

thank you so much for the heads up i really appreciate it.

 

The good news is that the problem is now fixed. The bad news is that it was an expensive repair. It was a problem with the Passenger Side Multiplex Control Unit. My Acura dealer charged me $175 for the diagnosis, $521.59 for the part, and $175 to replace it. Less 10% for parts and labor with my discount card.

You can save money by buying the Passenger Side MCU online. The part number is 38850-SZ3-A01. You can buy it from http://www.acuraoemparts.com for only $458.18 (plus shipping and tax, if any). I have bought parts from them before and I would recommend them.

Then you can try and replace it yourself. There's a little bit of instruction here:
/tsb/1996/B96-052.pdf

The other good thing that happened is my dealer told me that a lot of older cars were not passing their California Smog Test. Therefore, Acura performs an Emissions Campaign Service. I received an oil change, new spark plugs and an ignition kit (spark plug wires, etc.) for free!

I noticed that the remote car alarm fob now makes the car beep when we turn the alarm on and off. It didn't do this before. This was probably a function inside the Passenger Side MCU.

Good luck!

 

That's what I get for not previewing. When I attempt to type in the URL of another Acura owner website, it gets automatically erased.

Do this then: Google for "acura 96-052", then on that page, find "96-052" and click on it to see the PDF.