Originally Posted by leo2302
I need help. My taillight went out and as I was replacing the bulb, I noticed something wrong:
First, does anyone know what might have caused this?
Second, anyone know where I might be able to get the black wire harness? Or is this something I would have to take in to the dealership? It's a 2004 330i and it's the driver's side tailight
Thanks for your help!!
It's common enough that BMW issued a Service Bulletin for it: SI B 63 03 06.
It affects E46 (3 Series) sedan from 9/01 to 3/05 production.
Cause: Minor corrosion at the 8-pin rear lamp connector creates high resistance causing damage to the connector housing.
I had it happen on my wife's 2004 325i in the same spot.
If you're under warranty, you can try to get the dealership to repair it. If not, I've read other posts where the dealership might charge you $200 per side to fix it.
Since mine was out of warranty, and I didn't want to spend that kind of money, I read of other fixes and came up with one that didn't require any wire splicing or soldering. The gist is to fashion a stronger ground wire, attach a ring terminal at one end, a female spade terminal at the other, then attach the wire to grounding points on the car body and tail light.
About 3 feet of 14 gauge wire (I'd recommend stranded for flexibility).
Two quarter-inch inside diameter ring terminals that can handle 14 gauge wire
Two quarter-inch female spade terminals that can handle 14 gauge wire
Suitably sized heat shrink tubing to fit over the wire and terminal
Crimping pliers (often comes with wire stripping feature)
Three-eighths inch ratchet drive (preferred) with at least a six-inch extension
Spare bulbs (just in case you actually come across some burned out ones)
1. Unscrew the inside tail light, ease it away from the housing, and remove the wiring connector.
2. If the ground wire connector (brown wire #2 on the left rear, brown wire #3 on the right) is damaged, pull it out of the connector and tape it off with the electrical tape. If it's not damaged, leave it alone.
3. At least on my 2004, below the inside edge of the tail light is a removable plastic access cover (photo). Reach down inside and push the access cover out toward the luggage compartment and set aside.
4. Using the ratchet, extension, and socket, go through the access hole and remove the 10mm hex nut (photo), being careful not to let it drop.
5. Using a wire stripper, remove a half-inch of insulation from your supply of 14 gauge wire. Slip on a piece of heat shrink tubing over the wire.
6. Feed the bare wire into the bottom of the ring terminal, crimp with the pliers, then slide the heat shrink tubing over the connection and heat as required for a good tight seal.
7. Slide the ring terminal over the threaded stud you found in step 4, but don't put the nut on yet.
8. Curve your new ground wire along the same path as the existing eight-terminal connector, going an inch or two past as that's where you'll cut your wire.
9. Once you've made the cut, pull out your ground wire. Since the dimensions are the same for both lights, if you want to cut your second piece of ground wire the same size as the first, have at it.
10. Strip off another half-inch of wire, add the shrink tubing, then push the bare wire into the bottom end of the female spade terminal, crimp, cover the connection with the heat shrink tubing, and heat for a good tight seal.
11. Slide the ring terminal end of your ground wire onto the threaded stud you located in step 4 and carefully screw on the 10mm nut. Replace the access cover.
12. Above the bottom bulb at the bottom of the tail light is a quarter-inch wide piece of metal (photo). Place the spade terminal side of your ground wire onto this connection point (photo).
13. Replace any bad bulbs you find, reattach the eight-terminal connector, then ensure you're not pinching the wiring as you ease the tail light assembly back into its housing and twist to lock.
14. Put the key in the ignition and check to see the that the warning lights you used to get have gone out.
Then go do the other side.