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Sebastian Vizcarra
Sebastian Vizcarra, Porsche Meister Tech
Category: Porsche
Satisfied Customers: 350
Experience:  Porsche Factory Certified Master Technician
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Porsche Cayenne: My 2008 Cayenne V6 is equipped with a Black

Customer Question

My 2008 Cayenne V6 is equipped with a Black Bug Immobilizer when I got it. Unfortunately, it ( I believe) is occasionally causing trouble preventing me from starting the car for about an hour, usually after the car has been left with the ignition key in the lock for a while.
Is there anybody that knows anything about the immobilizer???
Submitted: 10 months ago.
Category: Porsche
Expert:  porscheguru replied 10 months ago.
Hi, I am going to ask some questions to see if I can help you resolve this. I need to ask if you have any other keys and if so does this happen with all of the keys? second, when it will not start, are you able to hear the steering lock "clunk" when you insert and remove the key? third, are there any warning messages in the instrument cluster when this happens?Fourth, has anyone checked your brake lights if they are working when this happens? Thanks and I will await your reply.
Customer: replied 10 months ago.
Hi guru, nice hearing from you.Answers to your questions as well as I can at the moment.
1. I have two keys and it happens with both.
2. I have not noticed the steering lock clunk, so I have to remember that for the next time. I do know that the fuel pump does not run for the duration of the problem. Once I hear the fuel pump, everything is fine again.
3. I had the engine light on once, but usually nothing.
4. Have not checked the breaklights. Why would that matter?
Expert:  porscheguru replied 10 months ago.
So the engine does crank but it will not start correct? I was assuming the engine did not crank but when you stated the fuel pump I started thinking. I will be going to bed soon and I know you are Sweden so we have a little bit of a time difference but I can help you. If this is a condition where the engine will not start but does crank over, then I want you to pull fuse 14 when the engine does not start. attached is the diagram and this ebox is in the engine compartment. By the brake fluid reservoir. This test will determine if the primary fuel pump is failing. The reference to the brake lights was the brake pedal must be depressed to start the engine. I will await for your reply and I will get back to you in the morning.
Customer: replied 10 months ago.
Funny, you think you have given a clear description of a problem, but.. So, when the car works I unlock the doors, open drivers door and I can immediately hear the buzz from the fuel pump. When it fails, no buzz at all. However, the engine may ignite and run for a few seconds on whatever is left in the pipe or where it is left. The car has never stopped once up and running and it always starts properly after about an hour. That's why I have suspected some kind of theft protection gizmo.
Expert:  porscheguru replied 10 months ago.
There is a microswitch in the door latch that triggers the priming of the fuel pump when you open the door. Those often go bad but that does not explain why when you crank the engine it will not start . Is the time frame for when it will not start always the same or does it vary?Next time it happens, try wiggling the fuel pump relays. The location is under the hood and by the brake fluid reservoir. Just take the lid off with a T30 (I think) and using this chart I am providing, wiggle the relays. Yes it is possible the DME is bad. I do not think it is immobilizer because that usually first blocks the steering lock and the alarm would go off. Maybe something in the DME but that would be the last resort. I would also ask for you to check the integrity of fuses 13 and 14 in the same location. See if they are tight in the fuse socket and no corrosion. Those connections at fuses 13 and 14 go directly to each of the fuel pump relays for the power supply "control" part of the circuit but it is also the main power supply to when studying the wiring diagram. The ground portion of the "control" circuit of the relay goes directly into the DME (engine computer) so I would also like you to reset the plug connection at the DME if you can or have someone do this for you. You have a difficult problem to diagnose and successfully repair even if you were a physical customer let alone doing this via the web. BUT this is the correct approach. Always do the lest expensive first.
Customer: replied 10 months ago.
Least expensive first, I don't know. The car has been at the Porsche workshop twice, all in all close to two months and nothing fixed.
I'm trying to force the problem and when I succeed, I'll look in to your suggestions.
Expert:  porscheguru replied 10 months ago.
If they have looked into this as a dealer should be, then the DME might be the culprit. Please look into my suggestions.
Expert:  porscheguru replied 10 months ago.
Wiggle the relays to try and force the condition to occur.