MarkGolf

Hi Everyone,

I have a question that, when I search, yields two answers. Perhaps I can present a slightly different question.

On a normal warm day in the UK, over 10 degrees Celsius, my GTS generally starts up nicely. However, on occasion, with the first turn of the key, it doesn't seem to attempt to start—just a turn and back to ignition. It can be embarrassing sometimes.

Recently, the temperature dropped to -1 overnight and reached 6 degrees Celsius during the day. When I tried to start the GTS for the first time, it took three attempts. Strangely, if I shut it off and immediately try again, or wait for 5 hours, it starts perfectly—like new in a flash. The battery is not old and is showing good health.

I also have an issue where the puddle lights on the driver's side door and the driver's side rear door flash. There's no pattern to it, but if I mess around with the door catch, I can get the lights to flash in sync with movements on the door latch.

Upon researching this issue, I was told that the door microswitch is responsible for priming the fuel pump. With this in mind, before a cold start, I fiddled with the latch, got the lights to stop flashing, and I believe I heard the fuel pump (a whirring sound from under the car). However, the car still did not start on the first turn of the key.

My question is, is there only one microswitch that could be failing, and is this single switch responsible for both the puddle lights and the fuel pump, or is there another switch that triggers the fuel pump separately?

Aside from the microswitch, other threads suggest the high pressure fuel pump is on the way out, even though the car runs perfectly all of the time and with my scan tool, seems to shot 38000-42000 mbar at idle, this dropped to 16000 when off but I haven't watch to see if that pressure fades off rapidly.

I hope someone can give me some clues, I guess first job would be to clean up/replace the drivers door switch. But just looking for some early advice from those with experience.

Thanks!

Capt. Obvious

It's probably the starter. Pretty common issue. I was having an issue similar to yours and now that I replaced the starter it fires right up every time.

Snowcruiser

This - mine was always a bit slow, then it started taking multiple turns of the key to fire. Replaced the battery first, which helped a little. finally did the starter, now it fires on the first try.

2008 GTS with ~100k miles.

Petza914

Think it's only one door switch for the puddle lamps, interior lights, and the fuel pump prime. On a cold morning, do a test where you open the door and specifically listen for the fuel pump to prime, then leave and come back 15.minutes later and open the door again, specifically listening for the pump again. If you hear the pump both times, then try and start the car.

If it starts properly you have a fuel priming or pump issue. Doing it twice without a start attempt will ensure the rail pressure is adequate for starting. If the starter only engages for a second and then disengages, it's likely a starter issue.

Snowcruiser

Does it make any noise when you turn the key, or start to turn over but not actually crank?

Klaird928

I had the same issue minus the puddle lights. Put the key in turn, get the normal clicking noises from the solenoid in shifter and steering column, but nothing at the starter. Pull the key out try again. The next time it may fire right or it may be on the 15th time. I replaced batteries, ignition switch including associated modules, and still had the same issue. I had a spare starter that I had rebuilt ~$100. Stick it in and have not had another issue with the car starting, for that scenario anyway. The purge valve was the next no start issue but that is for another thread.

minty007

Yep, same issue less the puddle lights on my '08 GTS last year. New starter and all is well.

na2ub

Sometimes we get too informed about all the possible problems. I recently had a friend who's car wouldn't start ask me if it could be the fuses, the computer, some anti-theft lockout ... to which I told him to replace the starter, which fixed it. Moral is, more often than not, if the car is not starting properly (assuming you have battery) it's usually the starter. I have heard that the cayenne's suffer from slow starts when the starter starts to fail, or in my case, the cayenne cazoo, when the starter gear doesn't disengage fast enough, causing a whine from the gear after starts.

Klaird928

This is true to some extent, other times we are just trying to gather more information and make an informed guess. Some people express what worked for them and others are throwing up a Hail Mary. We don’t want to get in the habit of adding another FAQ with vague answer either. I.E. 1) Q: I am getting this code #### what does it mean?. A: Replace your Battery. 2) Q: I have this strange electrical issue, what can it be? A: Fix the wires under the carpet. 3) Q: My Cayenne won’t start, what should I do? A: Replace the starter.
Almost every time someone asks a question one of these three answers comes up as a solution. The problem is that the Cayenne has so many issues that without a proper amount of troubleshooting the problem takes longer to resolve. If I am asking a question I try to include everything I have previously done. If I am answering a question I try to ask questions based on the experiences I have had.

MarkGolf

Hi All,

Just to update, I have started paying more attention to the door switch. When it's cold, it just does not work, even when playing around with the catch but on the times when I can get it to work, the car fires up instantly, everytime. So I think my issue is the door switch, thankfully. Although even that does not seem as straight forward as I would like to swap!

My back door on drivers side flashes too, so 2 switches to clean/replace!

Just an update to my issue.

Cheers

Petza914

Get some Deoxit D100 and spray it into the pin switches and work them a bit. It will bubble away the oxidation and make them work again.

phatz

P
Can that be done via the latch with the interior door panel on ....I dont recall

Crozzer

Some better advice above, but also adding the batteries on these things are more temperamental than one might expect. Fresh battery, use a trickle maintainer, especially helpful in cold.

symptoms there tend to be slow or long cranking times, so may not be specific to your symptoms, but might be related.

hearing the fuel pumps should be readily noticeable, even if faint. I can’t help but hear them now I know what they found like.

good luck!

Petza914

I just looked at mine again and realized it's not a simple pin switch like in some of my older cars and must be a microswitch in the door latch assembly. Not sure if Deoxit is going to resolve that type of switch issue and might need a new mechanism with working microswitch.

Gjcnbd

it’s a common issue my cousin got similar