| B2471 interior lamp/ B1971 inadvertent power loss
B2471 interior lamp/ B1971 inadvertent power loss
I discovered last night that the interior lights on my 99 Deville were not working. They would not activate when I pressed the unlock button on the key fob, opened the doors, or even manually using the headlight switch. The glove box light was out, the trunk light and both map lights as well. I pulled the codes and got a B2471 (current). This code was in the history when I purchased the car along with B1971, but I didn’t think much about it at the time because the B2471 shows as ‘interior lamp’ and I figured that one of my inside lights was burned out. Last night when I hit the unlock button and no lights came on, I tried the headlight switch first—nothing. Next, I started opening doors—nothing. Then they came on for a second and went out again. This seemed like a short to me so I started researching here on this site and then around the car. This morning I went out and disconnected the battery terminals and checked to make sure they were okay. Then I took the fuse panel cover off in the engine compartment to expose the ‘inadvertent power relay’. The whole black cover has to come off, which is easily done—just pull straight up. You have to move a cable and the windshield washer fluid line out of the way as you are taking the cover off. I unplugged the relay and it had a little blue corrosion on the prongs. I next looked inside the plug and saw a lot of blue corrosion. I sprayed it out with CRC Electronic Cleaner and used a pick to remove the corrosion (battery still disconnected). I then turned it so I could see the back side of the plug where the wires go into it (there’s not much slack in the wiring harness). When I did this one of the smaller wires popped out. It had corroded so badly that it had broken. I went to a junk yard and found another plug. When I got it home one of its wires was broken as well, but one was usable. There are actually four wires going into the plug—two big and two small. I used a small screwdriver to push the pin out through the bottom and then used a connector to splice it into my wiring harness. I sprayed the plug with a little WD40 to make it easier to slide the pin back into my plug. Now all is well. I put grease on the battery terminals, connected them, started the car and let it relearn its idle. Again, all is well and everything works as it should. At first I thought all my efforts were for nothing because when I opened the door, no interior lights came on. This is because it was daylight outside and the system only turns them on at night. I eventually remembered this and turned on the map lights and then used the headlight switch to make all the lights come on. I don’t drive the car much at night so this condition may have been coming and going for awhile. Like I said, the lights did come on last night for a couple of seconds after I started opening and closing doors, but I think that may have been because I had slammed one of them shut and it made the bad wire to the relay plug come back into contact with the relay. If you experience a ‘no interior lights’ condition, check the plug going into the inadvertent power relay. Mine was badly corroded and so was the one on the donor car at the junk yard. Alldata shows a good diagram where this relay is located. After you remove the cover in the engine compartment, it’s the relay that’s more toward the shock tower and closer to the driver’s fender. My relay is black and the plug going to it has four wires coming out of it—one big purple wire, one big red wire, one small orange wire, and one small brown wire. | 
