I’ve seen this happen in a couple of cars now and I’m not sure why. Perhaps someone who is unfamiliar with how they work gets in the car and tries to set the clock by spinning the knob, or a previous owner took the cluster apart and broke the tabs? Usually both knobs are affected though only one side is supposed to twist. Here’s how to take out the cluster and assess what’s wrong. As per usual disclaimer, the following is provided for information use only — no wagering. Disconnect the battery before working on any electrical system in your car.
It helps to have the steering wheel lowered and pulled forward as far as possible to get as much space as possible to work, or in this case, remove the steering wheel. The cluster is held in place with two T-20 Torx screws.
Remove them, and gently pull the cluster forward until you can reach the electrical connectors on the rear. The connectors have lock-levers. Gently depress the lock, and slide the lever forward to remove the connector. They are different sizes so you don’t have to remember which is which. Remove the cluster and set it on a cloth.
Press down on the white wedge and pull the black arm toward the top of the cluster to release
Gently pull off the two rubber outer buttons.
Gently pull away from the face to remove
Flip the cluster over and you will see a series of T-10 Torx screws (mine was missing a few of them). Remove the screws and gently lift the back off the cluster. The plastic button plungers should stay with the instrument cluster. Avoid touching any of the circuits or the circuit board and gently lift the board from the front housing.
Remove the screens which have the icons for the various warning lights along the bottom of the cluster. (More on these later.)
Now is a good time to clean the inside of the glass on the front half of the cluster. Use a clean micro-fiber cloth and a screw driver to reach all of the areas inside the cluster. Turn our attention to the reset mechanisms.
Circle shows broken spike.
They are delicate plastic plungers with a plastic spring on one end and a T section in the middle and should have a spike which activates a small button recessed in the instrument face. When you look at the instrument face, you can see how they work. The one on the left does not twist. The T is held in place so the only action is the plunger. The one on the right is used to reset the clock. It too has a plunger action, but also twists left or right about 45 degrees to move the time forward or back. It does not spin. If the plungers are in good nick, then chances are they just came out of their slots and careful reassembly should get you working again. More than likely, however, one or both plungers have lost their spikes. You can’t buy new ones, and if you buy a used cluster for parts, chances are they will also be missing their spikes as well. Fortunately, the internet has an answer. See this post on e46fanatics. We used it to fabricate new spikes.
Following the instructions, we wrapped a paperclip around a 1/8 in drill bit, then trimmed and bent it to match the photos. (I decided to paint the windings black to better hide them when reassembled.) Slide it on the plunger (tight fit), position, and glue in place. The one on the right side needs a larger surface area to activate the recessed button from various degrees of twist.
Use some glue to secure the winding to the plunger and then paint. Before you reassemble the cluster, you may also want to use black electrical tape to block out any annoying lights from systems you may have disabled such as the low washer fluid light if you removed the reservoir, or the seat belt light because you’re using different buckle receptacles (in my case, those from an E30 M3.)
Before reattaching the screws on the back, check that the plunger has seated in the slot.
Assembly is the reverse of removal.
When complete, the winding is barely visible.