mjdavis

Hi there. I'm having a problem that I don't think is unique, but a search of the forum hasn't uncovered a solution yet. Here are the facts of the case:
- 2008 Cayenne S with about 105,000 miles
- New battery about 9 months ago (just tested it, the battery is in good shape, reading 100% charged)
- Intermittently, we have trouble starting the car
- The starter will turn, but the motor won't catch
- We find that if we depress the brake pedal really hard, we can usually get the car to start

I'm wondering if there is a sensor on the brake pedal that let's the car know that the brake is down before starting. Has anyone had this issue before, or know how the brake pedal and starting sequence is related?

Thanks!

deilenberger

IIRC (and it's been a while since I've owned a 955..) you must depress the brake pedal in order for the engine to even crank over. I know that's the case on the 958 (where you can turn the key to the starter position - and release it - then press the brake pedal and the car will start..)

I have heard of this problem before on the 955/957 series - but forget what the resolution was. An advanced search of the forum might just turn up an answer. FWIW - most vehicles now have two brake switches. One that actually functions and makes the brake lights go on, and a second one that tests to see if the first one is working. It could be a failure of either, but in that case I'd expect a cluster warning of some sort.

19psi

If the brake switch isn't recognized, the display should tell you to depress brake pedal to start.

What does this mean?
The starter motor is spinning but the engine doesn't turn over? (bad bendix)
Starter motor is spinning and turning over the engine but the engine won't start?

LAPorscheGuy

If the battery is good it is most likely your starter.

MtnDogGeoff

this was a common issue with vw's, in my old gti i replaced the switch 4 times each with an updated part number.... when you hit the brake, do the rear brake lights come on?