US style taillights question

**deni2s** · 06-22-2017, 04:02 PM

Originally Posted by Vinci

Converting the brake lights to LED will disable your cruise control. You may have already noticed this.

Can't confirm - didn't used cruise control when used these modded hamann lights, need to check. Already sacrificed a lot (rear fog and reverse light). Probably some resistance to brake lights should fix that, if that's the case?

Originally Posted by Vinci

You do not need to use a load resistor to eliminate flash flashing of your turn signals. You can modify your flasher relay to remove the load comparison in it by desoldering the "M" shaped metal conductor and soldering a 10-watt (or so) zenier diode in its place. I did this with mine a year or two back and it works like a champ. If you use a strong enough diode (hence my 10W suggestion), I think you should still be able to run incandescent bulbs. I haven't tested that, though.

Thanks for insight, need to think about that. I like current config because it's plug'n'play and no mods needed on car before connectors. Ideal solution would be to modify the lights even more, so they behave exactly as stock, including fast flash when bulb goes out, but probably no need for that as there is always another backup led bulb on each side now. On the other hand, if I will choose to modify flasher relay, I might try as well get rid of the all 4 relays on the lights (required to make brake signal work more or less properly together with turn signals on the same bulbs). Maybe you have some bmw flasher relay schematics? If I remember correctly, on z3 electrical troubleshooting manual it wasn't really detailed.

**Vinci** · 06-22-2017, 04:11 PM

I misspoke. It's a Schottky diode, not a zener. I also meant "10-amp", not 10-watt. I will modify my old post to avoid confusion.

Check out post #6 in this thread: https://www.bimmerfest.com/forums/sh...ad.php?t=38677

I used the largest Schottky diode I could find at the time that was in an axial package (1 lead coming out of each side). I think I ended up with a 10-12A version. 10 amps at 12V is 120 watts. The flasher circuit should be under that, even with incandescent bulbs, I think.

I don't know if added resistance in the brake circuit would sort out the cruise issue or not. I think it has something to do with the ground being switched instead of the positive line. I have never found time to sit down and play with it, and since I don't drive the car much, the cruise issue hasn't been a show-stopper for me.

**deni2s** · 06-23-2017, 09:36 AM

Originally Posted by Vinci

I misspoke. It's a Schottky diode, not a zener. I also meant "10-amp", not 10-watt. I will modify my old post to avoid confusion.

Check out post #6 in this thread: https://www.bimmerfest.com/forums/sh...ad.php?t=38677

Thanks, I already found that thread yesterday.

What I would like to do, is to find some place where brake light wire is near signal to the the turn signal flasher. Then I could cancel the brake signal for the side where turn signal is on using just one additional relay (so turn signal is visible at the same time as braking). Not sure the brake light wiring goes under the front bonet. According to ETM it has some split X181 somewhere around brake switch (under pedal). Probably the closest turn signal wire goes from turn signal stalk. Need to investigate more.

**Vinci** · 06-23-2017, 10:08 AM

Definitely spend some time with a meter around the tail lights before you go down that road. If the ground is switched, you could end up with some bizarre issues with your relays.

All 3 of the "red positions" on my tail lights are converted to dual-filament bulb bases. I have them wired up so that running lights are low and brakes are high. If I don't have my running lights on and I turn on my turn signal, the turn signal AND the running lights flash with the flasher relay. If I have the running lights on, they work appropriately.

I haven't had time to mess with it, and since I don't drive without my lights on anyhow, it hasn't been an issue. Just a warning that things aren't as straightforward as they could be back there.