LED Backup and Turn signal Bulbs

[Love German Cars]

Subscribed!

 

[Zaxer]

The reverse is a 921 bulb, like these:
HIGH OUTPUT WHITE 6 LED 921 - 921 - Shop Bulb Number

$35 per bulb? Dang...

 

[Anaduff]

Another update...

🤔 I think I've reached the 'proof of concept' stage; turn signals work, brakes work, combinations work. The only anomaly is that if you are signaling a turn and then apply the brakes, there is about a 33% chance that the opposite turn signal will pulse very briefly (about 1 tenth of a second) and then will signal correctly (but with the brightness of the brake LEDS, no one may notice). No problem with brakes and then signaling a turn.

 

[Anaduff]

Schematic (still work in process) diagram attached. In an ideal world, we would have the shop & wiring manuals by now, but being limited to the existing wiring & lacking a 12V supply, this project is limited to the wires provided in the vehicle (plus the addition of the two brake signal wires from the tail lamp modules). The BCM really wants to see the 1.8 amps so the 8 ohm resistors are needed in front of the converter module, and since I don't want to draw too much additional current, I've replaced the amber turn signal bulbs with amber LEDs. Also the pulse train from the BCM isn't very clean so that requires the addition of the 2 electrolytic capacitors across the loading resistors (without them, you get the brake lamps flashing at 1Hz along with the opposite turn signal filling in the gaps).

Still have a few more things to try, but this it at about 90% complete.

 

[Anaduff]

🙂 ...OR you can just toss the adapter and spend some quality time underneath (and to the left of) the glove box. The green/violet wire coming from the black connector on the BCM is the front right turn signal, the blue/white wire coming from the brown connector is the front left. I attached a 2-cond cable to those and tucked it under the plastic door mouldings (hats off to Wlepse & Zaxer for their wiring suggestions).


Next signal needed was the 'high brake' wire which is a violet/white wire tucked-up above the left rear wheel well.


You will still need the 2x 8 ohm 50W to keep the BCM from hyper-flashing the turn signals; and I'll remind you again I've replaced the rear turn signal bulbs with LED's to minimize the current load. Signing off now.

 

[Zaxer]

🙂 ...OR you can just toss the adapter and spend some quality time underneath (and to the left of) the glove box. The green/violet wire coming from the black connector on the BCM is the front right turn signal, the blue/white wire coming from the brown connector is the front left. I attached a 2-cond cable to those and tucked it under the plastic door mouldings (hats off to Wlepse & Zaxer for their wiring suggestions).
View attachment 15327

Next signal needed was the 'high brake' wire which is a violet/white wire tucked-up above the left rear wheel well.
View attachment 15326

You will still need the 2x 8 ohm 50W to keep the BCM from hyper-flashing the turn signals; and I'll remind you again I've replaced the rear turn signal bulbs with LED's to minimize the current load. Signing off now.

Almost home...the gin will taste better when you get this figured out!

 

[Anaduff]

😀
Everything is buttoned-up in the car, no leftover dangly bits & everything works.

Now...

 

[supernoma]

Did anyone have an issue with LED backup lights staying on all the time? I used AUXITO 912 921 LED Backup Light Bulbs from Amazon and once on they would stay dimly lit. It caused the backup camera to stay on, even when the car was in drive. It was interesting to see the view from the camera going down the expressway.

It also disabled any changes to climate control.

 

[Zaxer]

Did anyone have an issue with LED backup lights staying on all the time? I used AUXITO 912 921 LED Backup Light Bulbs from Amazon and once on they would stay dimly lit. It caused the backup camera to stay on, even when the car was in drive. It was interesting to see the view from the camera going down the expressway.

It also disabled any changes to climate control.

same issue here - the bulbs would not turn off. I put the first bulb in - all good. second bulb went in...both reverse lights went on. Closed the gate - waited for the courtesy lights to shut off....both reverse lights still on. Tested shifter, drove it around the block...same results. The only thing that did work was returning them to Amazon. Refund issued and now back on the hunt

 

[Wlepse]

Is this normal? I just started to hook up my Curt wire harness and noticed on both sides there is masking tape which seemed strange, then I notice one conductor is cut on both sides. I looked at the wiring diagram above and see three wires are all that is needed but clipping a wire at the connector seems atypical to me. Not to mention masking tape seems strange.

 

[Anaduff]

Nothing unusual...masking tape shows up in a lot of places and the cut wire is actually a seal plug needed to fill the hole in the silicone seal.

 

[Wlepse]

Nothing unusual...masking tape shows up in a lot of places and the cut wire is actually a seal plug needed to fill the hole in the silicone seal.
View attachment 15362

Ok txs...I was just more concerned since there appeared to be a matching white wire coming out of the loom.

 

[Rhetoric]

Tons of great progress in here!

So who wants to help me figure out the rear fog situation on a TourX? 😉

I found the correct left, inner tail lamp housing and have the switch in hand. What I want to do:

• Wire up the rear fog (probably as simple as running a wire to the rear from the switch)
• Enable the rear fog icon on the cluster (this seems trickier)

I’m struggling since there is no service manual available yet; and even if there was I’d still have to read between the lines as what I want to do would be covered in a European version of the wiring diagram.

(I can start a new thread about this; but wanted to get some visibility here first.)

 

[supernoma]

Just tried the Phillips 921 LED bulbs on Amazon: same result as before- both bulbs always stay on once the second bulb is installed. Funny thing is one LED bulb works fine, just two messes something up. Anyone have 921 LED backup lights that work as intended?

 

[Anaduff]

• Enable the rear fog icon on the cluster (this seems trickier)

I was comparing the instrument display between the Buick & the Vauxhall owners manual--does the Buick even have a rear fog light icon?

 

[Rhetoric]

I was comparing the instrument display between the Buick & the Vauxhall owners manual--does the Buick even have a rear fog light icon?

The early 2018 red needle cars do, yes. I can see it has a spot for it. No idea if there is an LED there, but the cluster itself has a provision.

 

[Anaduff]

Just tried the Phillips 921 LED bulbs on Amazon: same result as before- both bulbs always stay on once the second bulb is installed. Funny thing is one LED bulb works fine, just two messes something up. Anyone have 921 LED backup lights that work as intended?

It sounds (er, looks) like the reverse bulbs are wired in series with something else, and the something else doesn't draw enough current to illuminate the filament on the bulb but will cause the LED's to glow. A way to check this would be to measure the voltage on the socket (bulb/LED removed) and see what's there. A 'normal' connection would have 0 volts (off) and about 14 volts (on) but in this case you might see 5 volts which would jump to 14 volts when in reverse (you'll need two people to try this & the one you trust the most should be the one with their foot on the brake).

 

[Anaduff]

Tons of great progress in here!

So who wants to help me figure out the rear fog situation on a TourX? 😉

Just some thoughts...
I'm assuming the rear fog switch on the switch module connects to one of the pins NOT on the original (like pin 4, 6 or 9) and, of course there isn't a wire attached to the plug to mate with it (Buick has 9 wires if front fogs are attached). So you have to add a wire, which would probably go to the BCM which most likely hasn't been programmed to recognize it & likely isn't going to be passing it on to either the instrument cluster or a 'to be installed' wire to the rear fog. So, there is an IC (Atmel U6032B) designed to act as a toggle relay which can be controlled by the momentary contact rear fog lamp switch and can drive a load up to 300mA (I don't know if you're planning to use a LED or bulb for the rear fog lamp). As far as the instrument cluster indicator is concerned, unless you see the appropriate symbol light-up on starting the car--we don't know if they installed a LED and just aren't illuminating it or whether they didn't install one at all. Either way, the cluster would have to be removed to check and perhaps another wire (and perhaps a SMD LED) would have to be installed and then connected to the 12V line supplying the rear fog lamp. Sounds like a fun filled afternoon project followed by a visit to a chiropractor...

 

[Rhetoric]

Great info, Anaduff! I was hoping this would be more like my '03 VW wagon where I just ran one long jumper line from the switch to the rear fog terminal. I should have known they probably complicated things a bit more so there is communication with the BCM.

For reference, the rear fog is an H21W bulb... not LED. The reverse lamp for the TourX is also not LED... H16W. Only the 'tail lamp' portion is LED.

 

[Anaduff]

OK--so a relay will be needed if you can't find out how to programme the BCM. Found this guide which allows a momentary contact PB to control & latch a relay (two actually) without resorting to using an IC.

Emil.Matei - On-Off switch using 2 relays - Four versions