Porsche Repair: 911 starting problem, porsche engineers, older models

Question
Hello Dave,

I read you are a 356 expert, do you know any good resources for 911 repair?

My 1999 911 is having a probelm starting, the dash board indicators wont 'power up' when the key is inserted; voltometer, fuel gauge etc dont get power, the warning lights dont get power, and and the starter wont turn on at all. Some systems do get power(headlights, windows, clock) The battery has been replaced with no improvement, even with a jump start.

Any info you have would be apprecited!
Thanks - Mike Halak

Answer
Mike,

You have a questionable ignition switch.  

Before I get to that issue, the systems that are getting power without a problem are ones that normally do not have to be controlled by the ignition switch.  For example, I assume that it's normal for you to be able to open your windows without the key being "ON".  Certainly the clock would never need a key to work.

I don't have a 1999 wiring diagram, but most cars have some systems that are always directly connected to the battery and can be utilized anytime, key or not.  I assume the headlights and windows did work without a key before this problem arose.

As for your ignition switch, it doesn't seem like it should be worn out so soon, but perhaps the combination of wear inside the switch and wear on the key itself is the answer.  

Without a current wiring diagram I can't be sure the '99's are the same as older models in this area, but for example, the older 911 models all have a wire directly from the ignition switch to the starter and when activated it tells the starter to take the battery power it is also hooked to and crank like heck.  In your case the contact inside the ignition switch that reaches this wire is faulty.

-------------OR-----------

You may just have some bad connections because of corrosion, vibrations loosening things or other little gremlins undoing the fine work of the Porsche engineers.

If you feel comfortable with this idea, here's what I would do, if it were my car.  I'd disconnect the battery.  I'd get the car up on jackstands so I could see or at least reach the starter and its wiring connections.  I'd identify the wire that comes from the ignition switch and connect a multimeter to it.  Reconnect the battery.  Have a friend turn the key trying to start and watch the mutimeter read battery voltage, like 12.8+.  If it does read battery voltage,  the car will START, so make sure it's out of gear.  If it doesn't start you'll need to actually trace that wire back from the starter to the ignition switch and verify the quailty of the conections at either end.  Then...

There's more to do, but it'll take a while to explain.  I'll be happy to give you the long version, but let's do this in stages.

Write back to me and let me know if you're willing to do this work yourself or if you have a friend who can help you.  Then I'll cover the steps in as much detail as needed to get to the bottom of this and get that '99 beauty back on the road.

Dave