04 Cayenne S Not Starting - No Warnings

[PJofSD]

Our 2004 Cayenne S intermittently fails to start when we turn the key. No starter sound. No warning messages on console. It just doesn't do anything.

Sometimes, after repeated tries, it will then start. Sometimes, it will not. One time, I tried everything I could think of, then left it sitting in small town South Dakota overnight. Went back the next day with more tools, but it started on the first try.

It is no longer reliable enough for my wife to feel safe driving it anywhere for fear of being stranded somewhere. Wife not happy...husband not happy.

Context:

Battery is new last year.
Battery voltage reads 12V+ every time checked.
Have tried pulling the relay near the battery under the driver seat, testing it functionality with a mini-12 volt battery and an ohm meter. It appears to function correctly.

I am thinking next step is to replace the brake switch.

Would love to get a wiring diagram for the car so I could trace the starter circuit, if that's even realistic.

Would also love other ideas for things to try to test to resolve the issue.

Thoughts?

- PJofSD

[968rz]

bad starter solenoid, it's mounted under the intake manifold.

[Determined]

I agree, check your starter solenoid. Your engine does not turn over correct? When it does on occasion turn over you can start it, correct?

[PJofSD]

Thanks very much. Yes Determined, that is correct, when it does work, the starter works fine. I pulled the solenoid off tonight, and will order a new one. I'll report back on the results.

- PJ