Hey fellow Z4 SMG owners (all 4 of you!)
Have you ever ridden in an M5 or M6 SMG and thought, wow, I really love that shifter! Well, I have, and thanks to a great deal from Tischer on the knob, the ingenuity of the M3 crew who adapted it for their cars, and a bit of my own time and patience; I present to you, the illuminated M SMG knob in an SMG Z4!
How To:
First, the required parts:
- OEM M5 SMG Shift Knob: 25-16-2-282-750 - SHIFT KNOB
- Connector Plug: 61-13-6-909-058 - Connector UNIVERSAL SOCKET HOUSING UNCODED
- 6 x Connector wires: 61-13-0-005-197 - BUSHING CONTACT
Getting the connector and contacts will ensure a 100% plug-and-play install / removal of the knob. Highly recommended.
Optional, highly recommended part: micro potentiometer. I got one from my local Radio Shack, part # 271-284
I'll call this out later in the Stage 2 install.
First, we will need to modify the base of the new knob. The small circular attachment ring will not fit our shift boots, and we will not be able to install it under our boots with that ring on, it has to go. I used a sharp utility knife and slowly, carefully, separated the leather from the plastic ring. It is just held on with some strong glue. Work slowly and surely around it and you'll get it.
Taking a look at the M5 SMG shift knob, we see it has a 6 pin harness coming out to control the illumination. Build your harness by inserting the 6 bushing contacts into the new socket housing. The wires will need to be connected as follows:
Pin# - Description
1 = Zone Reverse (switched GND)
2 = Zone Neutral (switched GND)
3 = Zone Drive A/S (switched GND)
4 = Night Illumination (GND)
5 = Night Illumination (switched +12v)
6 = Zone Lighting (switched/constant +12v)
I also tag labelled the ends of my wires to make it easier to keep track.
Stage 1 Install: enable dimly illuminated knob face for night-time driving.
To install: Pins 4, 5
This step is easy, and makes the whole thing worthwhile.
T-Tap pin 4 to the brown / black-stipe wire in the white harness for the gear selection LEDs.
T-Tap pin 5 to the blue / red-stripe wire in the white harness for the gear selection LEDs.
A sample of what you get here (sorry for the blurry pic, night illumination was very hard to photograph well):
Stage 2 (Optional) Install: enable Zone Lighting (not for the weak).
To install: Pins 1,2,3,6
This step is unfortunatly no small task of making connections to pre-existing wires. Without a good technical manual to the car, I performed extensive trial-and-error tests with a digital multimeter. I determined that unlike the M3's SMG II, our gear select lever emits an adjusted voltage signal to signal the ECU which gear the user wants to be in. (Not final selection of course, ECU can override). The M3 emits a switched ground for each position, so those guys got off easy. They can connect wires 1,2,3 with some T-Taps and be done. We will have to build our own leads. I had a hunch the position select LED indicator just below the shifter operates on the same switched ground principle, since when I tested its leads it had no discrete switching signal, instead it utilized 2 adjustible voltage signals to feed gear selection information to the small PCB that the LEDs are mounted to. Luckily, I was right (or I would have been
really mad) and what we need to do here is extend 3 leads from the negative side of the gear select LEDs.
Solder a small wire (I used 30ga, color coded) to the right side of each indicator LED. These are the small ones, make sure not to tap the general illumination LEDs (the bigger ones).
Route the wires carefully out the sides and re-assemble the housing.
With the switched grounds installed, connect up the 1 last wire, +12 for zone illumination. I connected it to the Red / yellow wire in the same white harness going to the gear selection LEDs, this way whenever there is illumination of the panel LEDs, the knob will light up also. This gives you position indication when you hit a button on the fob (before starting the car, or before key in the ignition) as well as after leaving. It will go out on its own a minute or so after leaving / locking the vehicle too.
Testing, double-checking, and more testing:
It works!
Something I noticed: Zone Illumination is BRIGHT! Like, retinal burning, distracting from driving bright at night. In the M5 I suspect this is controlled via central illumination, but here we are just cramming 12v through a very intense LED. So, to dim it down, I installed the potentiometer mentioned above. Splice it into the middle of wire 6, constant / switched +12. This gives you a nice turn-dial that will allow you to fine-tune and pick how bright you want your zone illumination to be, and then hide the mini-pot under the shifter. If you ever want to change the brightness, just pull up on the boot, adjust, and re-install. Quite easy and effective, not to mention $1.49 + 5% tax locally.
Re-installation:
Pull the harness and leather of the M5 knob through the hole in your Z4's shift boot. Its a tight fit, but you can get all of that material through there. Slowly work the wires down, being very careful not to pinch anything, and get the knob onto the shift stalk. Pull the Z4 shift boot up tight around the base of the M5 knob once more, and then push everything back into place.
A comparison of the two knobs:
The new knob is slightly lower, feels better, and most importantly, looks great!
Credit and Sources:
I would not have started this project were it not for some extremely helpful threads on other boards, specifically:
M3 DIY, from which much was borrowed / learned:
http://www.m3forum.net/m3forum/showthread.php?t=100928
Original knob swap thread, long but it had many helpful tidbits:
http://m3forum.net/m3forum/showthread.php?t=83712
Tischer's great special on the knob:
http://www.mileoneparts.com/partloca...catalogid=4462