I know this has been covered in loads of posts, but I couldn't find a "complete guide" that showed the simple process in one post... so thought I'd write one
Thanks go to CJ10Jeeper, Gannet and various others for the 1001 posts on this subject that enabled me to actually do this mod Requirements
1x Pre-facelift Z4 (Built before Oct 2004)
1x Medium-sized Posidrive screwdriver
1x Dremel with cutting disk
1x Cruise Control Stalk (EU BMW Part Number: 61 31 6 940 989
)If you don't have a dremel, then a coping saw would suffice.. at a push a sharp stanley would also doAlso, if you have a post Oct 2004 Z4, please see Gannet's copy of the retrofit instructions, here or hereYou'll also need the additional wiring harness "A" as shown in the above instructions. (EU BMW Part Number:61 12 0 411 248) Costs
The stalk cost me £60.75 inc vat from Sytner's Nottingham.Step 1
Disconnect the negative terminal from you battery. (It's in the boot, under the carpet, silly)I personally didn't do this, as I'm kind of partial to electric shocks. However, Srhutch kindly pointed out that doing this will prevent you blowing the DME... which makes this a good step to do!Step 2
Release the catch under the steering wheel column and pull it towards you as much as it will move.
Locate and remove the one posidrive screw, located next to the column movement catch:Step 3
Carefully remove the bottom cowel by gently pulling down on the bottom edge (the edge closest to the pedals).
Once removed, locate the free plug on the left side of the column. Mine was tucked in behind the other wire in the next picture.
Once found, gently pull more slack out from within the column, giving you enough spare to work with it.Step 4
Plug this spare plug into the socket on your new cruise control stalk, then slide the stalk into the guide rails attached to the steering column.I found I needed to put the back of the stalk in first, so that I had enough clearance past the large wires on the far left of the steering column
As you push the stalk in on the rails, it will eventually click to indicate it is fully in place.Step 5
Using a fine cutting disk in a dremel (or similar tool), carefully cut out the gap for the new stalk in the bottom steering cowel removed in step 2.
If you look carefully on the left side, you'll see that BMW have kindly left a faint outline of where you need to cut. I simply traced around the inside of this with the cutting disk, then used a fine sanding disk to grind the remaining plastic back to the lines.
After about 5 minutes of cutting and sanding, I ended up with the following:Step 6
Carefully re-attach the bottom cowel to the steering column, checking the fit of your newly cut hole. It can be a bit tricky to line up the cowel. I found that if you line up the very front "spikes" on either corner with the holes on the top cowel.
Now, re-insert and tighten the posidrive screw, then re-adjust the column to your liking before closing the adjustment catch.
And that's it!
To actually use the cruise control, push the stalk forward (away from you) to set the car cruising at the current speed (aslong as you're going faster than 20mph).
To speed up, push the stalk forward again until the required speed is reached.
To slow down, pull the stalk backwards (towards you) until you slow down to the required speed.
To return to the last set speed (after, say breaking or changing gear) press the button located on the end of the stalk.
To cancel cruise control, push the stalk down, depress the clutch or break, or accellerate to a speed faster than the set speed for a lengthy period of time.
Hope this is of help to anyone wanting to do this themselves!