Cayenne_Ben

Hey guys, tonight I noticed that the footwell lights, seat heater switch lights and all the overhead console switch lights and map lights have all stopped working. Is there a single fuse that protects all of these items?

deilenberger

Hey Ben - how about giving us a clue! Like what year and model is your Cayenne?

dave-t

how old is your truck battery? Could be time to replace. Get a battery test.

Marv

DELETED. After re-reading your post you also have issues with the footwell lights.

Try checking your owner's manual for a list of fuses and their locations.

Cayenne_Ben

Ah geez, sorry guys. I thought I had the info in my sig. I'll be sure to update that. Anyway, it's an '04 CTT. Brand new battery about a month ago.

deilenberger

How is the sliding switch in your overhead console? There is a springy contact plate on it that loves to come loose. If it does - best case the switch just doesn't work.. Worser case is it goes rouge and shorts out something.

I don't have a diagram handy - but it is entirely possible that these are protected by a single fuse since the ambient brightness of the footwell lights can be set using the overhead console (it also sets the brightness of the interior door lighting around the armrest.)

These can be set to a dim glow when the other lights are on and all the doors are closed and you're driving down the road. So.. possible one fuse is the problem - but you also want to determine what caused the fuse to blow. They don't just go bad spontaneously (at least very rarely..)

Since the truck is running and starting OK it isn't your battery, unless you have two batteries like some early 955's do and the one under the spare tire went bad.

Cayenne_Ben

I never touch the sliding switch, it's always in the same position. Single battery in mine. The ambient lights in the arm rests still work. If anything, they seem brighter. Maybe as a result of this failure they've defaulted to the brightest setting. I'll start checking the fuses but having owned this thing for a couple of years now, I know that sometimes these little electrical issues solve themselves!

Cayenne_Ben

Just to close the loop on this thread, it ended up being a burnt out 10a fuse in the #2 slot in the driver's side fuse panel. Replaced it and all is working as it should be again.

deilenberger

When it repeats (a 10A should never spontaneously burn out) you might try tracking down what's causing it. You haven't replaced filament bulbs with LEDs?

BTW - thanks for letting us know the findings - so few people do.

Cayenne_Ben

No I haven't replaced the bulbs with LEDs. I'll post back to this thread if the fuse continues to burn out.

Cayenne_Ben

Well unfortunately, the problem has come back. I have a couple of questions:

1. How easy are these things to diagnose/track down? Would the dealership be able to plug in and trace the fault?

2. Does anyone have any wiring diagrams they could post? I'd like to know what is connected to what on this circuit.

3. There seems to be conflicting info out there with respect to the fuse panel layouts. First of all, my manual lists both panels as being the "left side". Second, neither of the diagrams show a 10a fuse in the slot that I have one in (the one that keeps burning out) and neither diagram describes this fuse as protecting the affected electronics. Furthermore, the diagrams I've found online don't seem to jive either. Anyone have the correct fuse panel layout diagrams?

Thanks!

deilenberger

Rather thought it would. Fuses don't go "bad" they go open when something is wrong. Since you just replaced the fuse.. and didn't find what went wrong, it was a reasonable prediction to make.Fairly complex. And I don't think there will be anything to plug in and trace. The fuse has no knowledge of what device/connection/wire caused an excessive current draw - it just knows it experienced it. There is no memory there.Sorry - I don't. The copy of the Cayenne manuals commonly found on Ebay doesn't have the wiring diagrams either from memory (I no longer have that manual - no need to keep it after I traded the 955 in.)Where are you finding the fuse panel diagrams? Owner's manual? Since yours is an early model perhaps they corrected the diagrams in later copies of the manuals. Porsche has a website where you can download PDF copies of the owners manuals. Perhaps try downloading a 2006 one - I know that one was correct for my 2006 S/****.

My one suggestion - check the operation of the sliding switch right above the mirror (dead center near the windshield) on the top console. That's the switch for the interior lights. It comes apart. If it moves very easily - the sliding metal contact in it has come apart. It would then be drifting around inside the console and could be causing your problem. Porsche has a kit to fix that switch.

Other than that - it's the tedious job of checking everything that fuse protects and see if there is any evident physical damage that could be causing a short circuit. There isn't anything like a radar-detector power cord that's been added or something like that?

With the increasing electronic complexity of vehicles now - as they start to age and electronics starts failing simply from old age - it becomes un-economical to keep them on the road. Replacement parts will be scarce and costs astronomical. Yours is a simple model - only has about 8-10 computer modules in it. The 958 has something like 50. Some of the new 911's - according to the dealer - over 100. Scary stuff. Space shuttle complexity without the same quality of build (and even then..)

Cayenne_Ben

Ok, it seems I've made a boo boo in reading the fuse layout. What I thought was fuse #2 is actually fuse #12. I was reading left to right instead of right to left. Anyway, what this revealed is that the fuse in question should be a 20a, not a 10a as was the one that was in there. Now it should be said that it's been fine with the 10a fuse for the two years that I've owned it.

The sliding reading light switch was functioning as it should, though I rarely if ever use it. When I checked it today it felt good and solid.

I don't have any after market equipment installed. Tomorrow I'll try a 20a fuse and see what happens.

wkearney99

I'd be very cautious about fuse values. Since it's used then who knows what shenanigans someone pulled in the past that led to using the wrong fuse value. It would seem odd for it to have been wrong since new and now suddenly fail repeatedly with that value. The fuse panels are a bit tedious to read, so getting it wrong once would make me want to be DOUBLY sure about values.

Going from a 10A to a 20A means that whatever has been causing the 10A to blow is now going to have a greater chance to heat up any of the wiring that goes back to the fuse panel. As in, set it on fire due to overheating. If you're SURE the factory panel called for a 20A in that location then maybe it'd be fine. But given the expense of an electrical fire (essentially a 'total loss' event for a vehicle that old) I'd really want to avoid that kind of gamble.

The debugging process for electrical overloads causing fuse failures is tedious and complex (read: expensive). The simple approach is to disconnect things and leave them disconnected while looking for the problem to reappear. That and popping open the connectors along the circuit and looking inside them for signs of damage from heat. But, again, the labor to do this is excessive given the amount of disassembly necessary to get at the connectors. Using an ammeter can help determine which branches of a circuit are consuming the most wattage, but again, it's really tedious to do this.

One thing to look for is any sign of water damage or corrosion. If you see any of that then ALL BETS ARE OFF. It's best to sell it, quick. Because once wiring is damaged from corrosion the only permanent way to solve it is to replace the wiring, often a fair distance from the point of any corrosion as it, essentially, 'wicks' it's way up the strands, inside the insulation. Again, the labor involved here is considerable and likely to exceed the value of the vehicle.

So I'd start by double-checking the factory fuse recommendations, even if it meant having someone else come look at it. I would not just leap to doubling the fuse value.

Cayenne_Ben

Circling back to this post...

I did confirm that fuse #12 in the drivers side (left) fuse panel protects the interior light circuit and should be 20A. Last weekend I pulled the overhead console to check the condition of the light switch. It was perfect. No melted plastic and good, clean contact points. Interestingly, with the overhead panel out I tried installing another fuse in the #12 slot and it again blew immediately. So evidently the cause of the short is not within the overhead panel itself. I'm still trying to track down a wiring diagram so that I can see what components are on this circuit. That way I can start checking one by one.