This article is one in a series that have been released in conjunction with Wayne's book, 101 Projects for Your Porsche 911. The book contains 240 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 650+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Porsche 911 owner's collection. See The Official Book Website for more details.
One of the most common electrical items to fail on some of the older 911s is the ignition switch. This failure can show up in any number of ways. The car can refuse to start some of the time, the key may not turn too easily in the ignition, or strange electrical problems like the headlamps flickering on and off may appear. Either way, the correct solution is to replace all or part of the ignition switch.
Probably the most difficult part of the whole procedure is the removal of the switch from the dashboard. On later cars, the switch is hidden behind a large, circular plastic disc. To remove this disc, simply unscrew it from the dash. On the earlier cars, there is a small plastic ring that needs to be unscrewed in a similar manner. Once the ring is removed, you can see the ignition switch assembly.
The switch itself is comprised of two separate sections, one that holds the key and the lock mechanism, and another that contains a somewhat complicated electrical switch that controls the starter and the other electrical systems of the car. The good news is that the electrical portion of the ignition switch can easily be replaced on 1970-89 911s. Typical cost of this part is about $55. Earlier cars will have to make do with finding a good used switch, as new ones are no longer available. If your key doesn't turn too well in the ignition, then chances are you have a worn out tumbler. You can attempt to rekey and refurbish the tumbler yourself (see Project 76 on lock rekeying for more details), but the process can be quite difficult. It requires that you drill out a pin that has been pressed into the housing. If you make a mistake, you can damage the entire assembly. In other words, the ignition switch assembly wasn't really designed to be taken apart.
Once you can see the ignition switch, you can probably clearly figure out why the next step is the hardest in this procedure. The switch is bolted to the frame of the car with what's known as a break-off bolt. While this may help deter thieves, it also makes your task a lot harder to accomplish. To remove these bolts, take a die grinder or Dremmel tool and grind off the top of the head. Once the heads of the bolts are gone, you should be able to pull out the switch. In some cases, you can also grind a slot into the top of the bolt, and use a large screwdriver to remove the bolts. Removing the steering wheel will probably give you a bit more room to work (see Pelican Technical Article: Replacement of Steering Wheel Switches).
Once you have the bolts removed, you can now crawl under your dashboard and remove the switch. Begin by loosening up the nut that holds the ignition switch onto the steering wheel lock. On some cars, you may not need to loosen this nut up, as the switch may just slide out of position. Disconnect the large 1.5" electrical plug from the ignition switch. The entire assembly should be able to be removed from the car now. You may have to negotiate a path through the maze of wires and cables that run underneath the dash.
Once you have the switch out, it's very easy to replace the electrical portion. Simply unscrew the two screws that hold it to the back of the switch, and replace it with a new one. The switch has a locating pin cast into the housing, so there is only one way that it can be put back together.
Replacing the electrical portion could most certainly solve some ignition and starting problems. Electrical systems flickering on and off as you turn the key are a good clue that your switch is worn. Also, a bad switch sometimes causes unexplainable starting problems where the starter coil doesn't even click. I even had one car that wouldn't shut off the starter after the engine kicked over. Both the engine and the starter kept running together: even after I had removed the key!
If you are planning on rekeying your ignition key, get ready for a very difficult job. In order to remove the tumbler assembly, you need to carefully drill out the small pin that is located on the side of the tumbler housing. Make sure that you use a sharp drill bit, and be prepared to spend some money for a new ignition switch if you happen to mess yours up.
The replacement process for the ignition switch is pretty straightforward, except for the final installation of the switch into the rear of the dashboard. You should use new original equipment break-off bolts that are commonly available from your local parts dealer. The heads of the bolts will break off automatically when you torque them down. Or, if you are going to remove the switch again, use regular bolts.
From the factory, the ignition switch is bolted into the dashboard with break-away bolts. If you're lucky, the previous owner has already replaced the ignition switch at least once, and the bolts have already been removed. When replacing the switch back into the dashboard, you can attach it with four break-off bolts.
The view from underneath the dashboard affords us a look at the ignition switch and its electrical connections. It's nearly impossible to remove the electrical portion of the switch without removing the entire assembly. Make sure that you loosen the steering wheel lock bolt on the left before you attempt to remove the switch.
Shown here is the electrical portion of the switch removed from the remainder of the assembly. After many years, the electrical portion is usually what wears out, resulting in intermittent starting problems with the ignition key.