Luciendar21

Background:

1. Major repair over the last few weeks and the battery was disconnected and also replaced during this repair.
2. Keyfob low-battery warning has been going off on start since before the repair.
3. I had a blown front AC fan fuse, I stole the transfer case fuse temporarily to ensure I had defrost on a cold rainy day. I just got replacement fuses in the mail and replaced all of the fuses.

Got the vehicle back last Wednesday, drove it to work on Friday and had no issues, started up just fine on the way to and home from work. Didn't drive it Sat, but went to drive it today (Sun) and I get nothing when I go to start.

Cayenne is an '06. It has Entry and Drive. The keyfob locks and unlocks the doors fine. I replaced the battery in the keyfob, it continues to lock/unlock the doors fine. I have been using the keyfob to start the vehicle, but if I put the dummy key in the keyhole and put the keyfob on the other side of the garage it properly tells me No Key Found. When they keyfob is used or in the vehicle it doesn't give that warning.

All I get on key insert is the Porsche crest on the dashboard, no warnings or alerts. The radio comes on fine.

I noticed as I was standing around trying to think and figure this out a few things that seemed anomalous.

1. The radio (factory) seemed to make some noise like a CD was inserted intermittently as I walked around the vehicle. Not sure if that was from me triggering entry and drive or something else.
2. There was a clicking sound from under the steering column, like a relay being triggered.

Any thoughts on what I might be doing wrong or what might be going on? I'm at a loss.\

Edit: Oh, and steering is locked also and I can't unlock it. Brake doesn't feel "hard" to press.

Luciendar21

So, I dont get it, but fuse 54, left fuse panel... I decided to check them all just in case one was blown. This fuse was just missing and was clearly indicated as needed by both user manual online chart.

I cant imagine how adding a headlight adjuster fuse would solve the issue, not can I wrap my head around how the headlights were adjusting just fine, but the car started.

If somehow my quadruple checking was incorrect and it was 53 that I swapped, I still dont get it because I've been using and driving the car without issue. I'm baffled.

Petza914

Sounds like you have an intermittent issue and that it was coincidence that it started the last time it did. There's a microchip in the steeri g column that I've read can go bad and completely immobilize the vehicle, but I think it displays an immobilizer message.

Try and open your rear power hatch 3 times in a row. Does it ever open part of the way then get stuck? That's an indication of a weak or failed battery, which could exhibit similar symptoms to those you described. How old is the battery?

Luciendar21

The battery is all of 7 days old.

It doesn't feel like the steering column sensor issue, since there are clear indications it recognizes the key when it is in the car and does not recognize the key when it is outside of the car.

I don't think I have a power rear hatch. I haven't given it much thought as I've driven the car for less than a week worth of trips since I got it... that and the hatch struts are blown and need replacing.

When I got the car I feared the battery was low and causing issues, as neither the front air conditioning fan nor the speakers were working. However, when had a look at the left fuse panel I found the front air conditioning fuse missing altogether, and the rear air conditioning (which my car doesn't have) had a fuse that was damaged (like the gel case was crushed and the fuse material was open to air). Gave me a huge boost of confidence (not). After battery replacement and replacement of fuses both speakers and AC worked. Of course the saga continues now as speakers have cut out once more. Back into the fuses I go .

Luciendar21

Well f*** me. Episode 2 of the same behavior, only this time instead of the comfort of my garage, it's on the bottom floor of an underground garage at work. Far away from service to help guide the diagnosis.

I'm at a loss (and more than a little frustrated). As I said before, there are clear indications that it recognizes the key, both in that if the key is outside the car there is a message on the screen and... and this is where it gets fun, in that the key turns and when you turn it on past accessory position like you're going to start the car, there is an audible click/clunk behind the ignition.

So I've got two ideas:

1. The keyfob RFID antenna used for the key detection is failed. Earlier today I was mindlessly fiddling with the key while talking with someone and I popped the battery cover off. I knew immediately it was a bad idea, put it back together and hoped for the best. It's worth noting my one keyfob is not exactly in great shape. It's very worn and has a rattling part inside of it. I worry there's a loose solder or even the RFID antenna has broken off, or just a metal fragment is present that is interfering with the reception of the antenna.
2. If I understand correctly, a common problem is that the steering column lock motor will fail. My steering column is very much locked, and the audible click when I turn the ignition makes me think maybe there is a motor/solenoid that is failing to unlock the steering wheel.

When I insert the key, I get the Porsche logo. When I turn the key, I get no change (no immobilizer message). When the key is not present (outside the car) I get key not found, the behavior with the key natively vs the Entry and Drive dummy key is no different.

My next action tomorrow is to try to pull and reset left side fuse #41 for KESSY/ Entry and Drive/ Immobilizer.

kadn33

I would suggest you to have a look at the wire loom under the driver's footwell carpeting for moisture due to clogged drains that would lead to wire corrosion, just to make sure you are good there. Do a search in the forum for pics and how-to.

If no findings then you can focus in what looks to be a steering lock failed. Do you have any scan tool?

Luciendar21

I have some cheap bluetooth ELM327 readers, and one older more powerful USB ELM327 reader, but none that are Porsche specific. I believe there was one that was in the couple hundred dollar range that was mentioned here in a thread, would I need that one for what you're describing?

I was planning to upgrade the car with an Android head unit, and in the process was hoping to take a reader and set it up for a constant connection so I could monitor and get car stats on the head unit. Not sure which reader to get for that, possibly just one of the cheap bluetooth ones I have.

Right now I'm just trying to get the car out of the parking garage at work. For it to fail here is... embarrassing and stressful.

Luciendar21

Update: I pulled fuse 41 (KESSY) and let it sit for 5min, then reinserted. It worked, I got the vehicle home. Now I'm debating how paranoid I should be about driving anywhere.

Not sure what to think.

kadn33

Having a porsche specific scanner would certainly allow you to figure out what is going on after communicating with the possible affected electronic modules. I also proposed the wiring corrosion check since is a common issue that might lead to electrical gremlins.

For an easier check of moisture under the driver's footwell just raise the carpet and check the foam underneath: if it is wet go ahead and check the wires and if it is dry forget about it and focus in the no start issue.

There have been many cases of KESSY modules and steering locks going bad because of a bad steering lock motor or bad soldering or resistors that would stop the car from starting until reset with scanner: maybe you achieved the same by removing the fuse but it is likely to happen again.

In any case this is just guessing and I would start by checking the car with a scanner for fault codes.

Regards

gibbsy

Is this the original key from the car.
Reason I say this is.......an aftermarket key that has been coded by a non Porsche service centre exhibits symptom's very similar to your describing.
I have tried to replace the key on my 955 CTT only to see this

New key ordered from the dealer & coded, no issue now 7 months.

Crozzer

I think this car hates me.

after few days of scratching my head about having to try turning the key more than once to get it to start, I’m now dead. Thankfully in my garage…

symptoms:
- with key in, Porsche crest appears
- on key turn, nothing. No accessories, no warnings, no starter motor firing, etc.
- once, it sort of worked; all accessories came on and started cranked, but then dies without engine start and all accessories go off

note I can’t run a scan tool b/c it won’t turn to “on” ( or rather the key will rotate but the car stays “off”)

but when I could run a scan tool, and I have done so extensively over the past few days, no errors from kessy. (No errors at all, other than a bulb out. Again.)

Crozzer

As soon as I hit send (of course)…
closed rear hatch, unplugged transverse control module, now working. Open hatch and plug 🔌 n the module, still working.

how do I prevent getting stranded?

is there a proactive fix if this is happening intermittently?

no error from kessy, or any others, from latest scan.

BobcatBrian

You need to figure out what was wrong. This thread seems to have some advice: Ignition switch help

Was your steering lock active? If you could turn the key and the wheel, I would think you have communication between the FOB, the KESSY, and the ELV. But you may not be getting a start signal from the KESSY to the DME. I'm not sure why. It COULD be a weak fob battery, a failing immobilizer in the fob, a KESSY problem (resistors?), a wiring problem, etc. Have you replaced the fob battery? Do you have a second key fob that works? Have you checked under the carpet for wiring damage due to clogged drains?

Crozzer

Thank you for all of this. I’ll be checking them off and will go see that thread (on a personal note I think we all do huge favors when we cross link like that. It helps the forum. Thank you!)

yes, steering wheel was free.

- replace fob battery: one year old but will do.
- get 2nd key: I think this is the excuse I need to plunk down $700 for a new key and programming on a car worth not a lot more than that…
- loose wiring: I hate these kinds of intermittent hardware issues. Does anyone ever have luck with this? I’ll try…
- I’ll be curious if my shutting the tailgate and unplugging the module has anything to do with this other than a pause and some impact vibration on the car…

BobcatBrian

No problem. These cars are very complicated but many of the problems are simple fixes. I don't see how closing your tailgate could be related unless it somehow nudged your KESSY module into doing something it wasn't. I imagine not being able to scan the car is a huge obstacle in diagnosing this...otherwise you might have to throw some parts at it, which can get expensive! The second key, while also expensive, is a good idea though.