Tail light warning on, but tail lights OK...?

[Paul328Ci]

The tail-light idiot light on the dash of my 2000 328Ci illuminated the other day. OK, no big deal, it's just a dead bulb. BUT all the tail lights are working.

So what else can this indicator light be trying to tell me?

I hope this isn't another electrical system mystery. :-(

(I'm not sure if this is related, but the one thing that stopped working is the trunk release handle. I can open the trunk via the key button, and the release button in the front footwell.)

[JKidd]

Sometimes they get a little corroded and sent that signal (like the bulb is burnt).

[ohdaveplease]

The brown wire in the tail light harness is too small and has a tendency to fail. There is a tutorial of the fix on e46 fanatics with photos. Easy permanent fix DIY
You splice a wire with an alligator clip to the ground and ground it to the tail light housing. It took about 5 minutes each side.
This drove me crazy for months This was the only "fix" everything else was temporary
04 E46 325i Sport,Manual,Silver Grey/Black leather.my car
90 Mazda Miata 90k original Red with Black........toy car
01 Subaru Outback LL bean edition h6...........wife's car
past BMW's: .
88 735i e32 Black/Tan...93 325i e36 manual Electric Red/Black *my first NEW BMW!...00 528i e39 sport,manual Electric Red/Black

[@ otto99]

I had a brake light out signal on my E34, and the wife was looking and said "Nope, both of them are on." Imagine our embarrassment when both of us completely forgot the CHMSL is on the same circuit, and was burned out.

Greg

2005 330Ci ZHP

[Paul328Ci]

Thanks for the suggestions.

Upon closer examination, I found that the passenger-side backup-light was not working. Even though the bulb looked OK, I replaced it just to be sure. The new bulb still won't illuminate, the warning light still shows and the trunk lid release still doesn't operate. There must be some connection between the backup light and the trunk release that is causing problems. My fear is that something is wrong with the wiring harness going to the trunk lid.

I guess I'll have to get the car to the shop. :-(

[Stinger9]

[sk3lly]

replace the socket on the reverse light. They are cheap. The one dealer that I used to use just included new sockets when you bought bulbs. Only use bulbs from a dealer. Auto parts store bulbs will cause you issues.

OhDavePlease's comment does not apply to your car. He has a sedan which uses a tailight panel and that problem does exist on them. Your car uses a tail light housing with individual removable sockets attached to dedicated wires. That ground issue does not exist on your car.

As far as the trunk release goes, it sounds like your key position on the trunk lid is turned to valet. Try putting your key in the hole and turning it 90 degrees and removing it then try the touch pad under the lip. Also make sure that both front doors are unlocked. If only the drivers door is unlocked the pad will not work.

If the reverse light bulb and socket does not help check your two bulbs that illuminate the license plate? I too have a 328ci and one of those bulbs caused my light to come on but I did not think to check those. Once I did it was fixed.

Good luck.

[dembooks]

some connection - or no connection is the problem

look to a pinched/cut wiring harness for the trunk lid

very common

see a BMW dealer - they will put their finger
right to the problem - they see it every week


or


you have a 'burned' bulb holder unit - another common issue

[Paul328Ci]

Thanks for the tips, Sk3lly. I checked the license plate bulbs and found one that wasn't working. I replaced both with new bulbs, but that didn't fix the problem.

On ODavePlz's advice, I checked the E46 Fanatics site for the grounding fix but, as you say, that doesn't seem to apply in my case since the problem seems to be specific to the trunk lid electrics.

I'll call the dealer for a new socket assembly and see if that helps.

As for the trunk release, I tried different key positions as you suggest, but the problem remains. I can hear the switch click when I press on the release, but nothing happens. At least I can still open the trunk by other means.

The dead backup light and the non-functional trunk release switch both occurred at about the same time, which has me worried that a more difficult repair will be required.

[ohdaveplease]

coupe and sedan
04 E46 325i Sport,Manual,Silver Grey/Black leather.my car
90 Mazda Miata 90k original Red with Black........toy car
01 Subaru Outback LL bean edition h6...........wife's car
past BMW's: .
88 735i e32 Black/Tan...93 325i e36 manual Electric Red/Black *my first NEW BMW!...00 528i e39 sport,manual Electric Red/Black

[Paul328Ci]

[josephwdickson]

I had problem with rear light on left side wiring harness on lr tail light melted. Replaced lr socket and ran heavy gauge ground wire

[Paul328Ci]

I ended up taking the car to a BMW repair shop (not the dealer) since the obvious fixes didn't help. The mechanic diagnosed the problem as originating in the wiring harness to the trunk lid, as I feared. When I told him that I had the dealership repair the same harness for similar problems less than 2 years ago, he said they did a lousy job. But what else would he say? ;-> A good 2+ hours of shop time, plus some small parts, plus tax. And on top of that I bought a socket assembly from the dealer that I didn't need and the dealer would not accept for return. (Hello, eBay?)

It seems that there is a basic design flaw with that harness as, in this model anyway, the harness is required to flex every time the trunk lid is opened and closed. Enough movement can eventually cause insulation to rub away or the wires within to break.

Lessons learned:

1) If there are mysterious electrical issues in the trunk lid, check the harness.
2) A special order electrical part from the dealer cannot be returned for refund.

[BlueMW]

But a bulb maybe going bad and causing elect resistance. Had this happen and found one bulb darkened and ready to go out. Once I replaced it the warning light eventually went out.