Help! Turn signal failure?

[IVI]

2006 Z4 M Roadster.
Front passenger headlight, turn signal bulb closest to grill won't blink. Bulb out warning in instrument cluster. Replaced bulb, no luck. Replaced bulb socket, tried 2 other new bulbs, no luck. Took it to shop to have them diagnose it, they said the problem was actually a failure with the passenger tail light housing, which needs to be replaced.

How can the tail light affect that particular turn signal in the headlight? This makes no sense to me. Anyone have any ideas?

[StickMon]

I call shenanigans.
The tail light housing is mostly a hollow box.
Does the rear turn signal work?

That said, I have no idea what you're problem is.
There's a connector on the headlight assembly. I would start there and see if I have voltage.
Matter of fact, I would start with the WDS and see if the inboard and outboard lights are on separate wires.

[IVI]

Right?! Rear turn signal works fine. Should note I have white LED bulbs in reverse sockets, haven't had any problems or errors for about 6 months of use. Shop guy said reverse LEDs shouldn't be the cause of this problem. Still, these cars are apparently very temperamental with any lighting changes at all, so I will try putting the crappy dim OEM incandescents back in and see if that solves it.

Also found this thread:
http://www.z4-forum.com/forum/viewtopic.php?f=3&t=84633

Wiring diagram below suggests no connection to rear lights other than maybe at the A3a light switch cluster represented by the gray bar at the top. This is the switch cluster left of steering wheel as shown here: http://www.z4-forum.com/forum/viewtopic.php?t=1586.



I will follow up after testing the OEM reverse bulbs for a few days.

[StickMon]

So there are separate wires for inboard and outboard front turn signals.
I would pull the connector from the headlight assembly, hit the turn signals, and see if there's voltage on both pins 5 and 6, with respect to ground pin 1.

Seriously doubt any impact from the reverse lights.
I have non "error free" LED reverse lights and everything works fine.

[IVI]

Well... after replacing the LED bulbs with the OEM incandescents, the problem appears to be resolved. Here's what happened:

1. Replaced LED bulbs with OEM incandescents.
2. Went on road trip with car club. Stopped several times along the way.
3. First several stops, after starting the car, no error. However, on first use of the turn signal, two normal blinks and then error + hyper blinking.
4. After 3 stops like this I discovered that I could use the signal for the first two normal blinks and then shut the turn signal off before the hyperblink error. This method also did not trigger the error. Drove like this for 50 miles, only using the turn signal for two blinks to indicate lane changes.
5. After final stop before heading home, I decided to test extended use of turn signal. Two normal blinks, then... more normal blinks! No errors!

I have no idea where the weak link is, but apparently when BMW says don't mess with Texas they mean business. I'm happy I didn't just take the shop guy at his word and go out and buy $300 worth of tail light assembly though. And I still want to find a competent electrician who can replace all (ALL!) the incandescents in the car with LEDs for me, minus the dash warnings.

[StickMon]

I've replaced all of my external lights with LEDs, save for the front turn signals.
The LEDs I've looked at are a little fatter and a good bit longer than the incandescents.
I haven't had the guts to try and jamb one home.

[IVI]

What supplier did you buy from, StickMon? Did you use resistors to cancel out the error warning?

[StickMon]

This.
And these in the angel eyes.
Plus random eBay bulbs in the hamburgers and front corner markers.

Red LEDs weren't available 2 years ago when I did mine, such that I could find.
I think Bimmian has them now.
6000K white LEDs in the brake lights makes them light up pink.

Had to code out the error for the angel eyes.
I have my panic brake lights wired in parallel with the mains, and resistors terminating the wires from the lighting module that used to go to the panic brake lights.

[IVI]

Awesome, thank you!