I hate electrical stuff...help needed!

I have a 2004 C4S Cab. Tonight, as I drove home I noticed that i was getting a fast flashing blinker on the passenger side of the car. Sure enough the front turn signal bulb was out. No big deal, I'll get a new one and replace it this week. As I locked the car and prepared to walk away, however, I noticed something strange. First, I could see the engine bay light shining through the vents in the spoiler. Then, the alarm beeped once to tell me something was wrong. And, finally, I noticed that the red ambient lighting inside the car was still on even though the other lights were all off. I opened and closed the engine cover a few times just to make sure it was operating correctly and it seemed to be. Eveything inside the car seemed to be operating fine, too. After searching around and testing things a bit, I disconnected the battery. I then reconnected it and the lights stayed off initially...until I tried to rearm the alarm. Then everything went back to wacky. I disconnected the batter one last time before calling it a night. Any thoughts? Has this happened to any of you? Do I just need to bring it in for service? Eric

Electrical problems suck. At least start with checking battery voltage with a real volt meter, not the cars gauge. Low voltage, bad grounds, moisture, and alarm problems also cause crazy stuff to happen.

The alarm beep is probably your best clue...you have an open zone somewhere, probably the engine lid given that the engine bay light is still on. The alarm system thinks the engine lid is not secure, and the light being on means it thinks it is in the open position. First check the engine lid light switch and electrical connector. You probably won't have to go much further than that.

Thanks -- yeah, electrical problems are, by far, my least favorite. It's been relatively dry here so the car hasn't seen much rain in the past couple of weeks. I had some moisture built up in my headlight but that dried up. I was never able to locate the source of the moisture -- no major visible crack or anything -- but I'll remove the headlight and start from there. Stuff like this always feels like a bad ground or a short to me neither of which excites me. -Eric

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Initially, I thought I must have somehow popped the engine lid without realizing it. I opened and closed it a number of times to make sure it as latching. I'll take a better look at it today and see what I can find. What really threw me for a loop though was the ambient lighting inside the car. Why would the little red LEDs inside the car stay on because the engine lid was open? -Eric

I'm sorry....what little red LED's? The alarm light is center on the dash. It flashes depending on the state of the alarm. If it is the ambient lighting like from the center roof console and door panels that stays on then it is something like a door micro-switch but I didn't want to go there first. I would check out the engine lid switch first. If that clears up the alarm beep then maybe do a system reset by disconnecting the negative terminal on the battery for 10-15 minutes, reconnect and see how things go from there. Another thought - the ambient lights stay on for a short period of time even after the doors are closed. Do they never go out? Have you tried locking the car and seeing if the lights go dim then out? Also just throwing it out there - a lot of strange electrical problems center on the electrical part of the ignition switch. Did not want to go there first but just throwing it in here maybe for later if you don't discover the problem.

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The LEDs I'm referring to (at least I've always thought they were LEDs) are the ambient red interior lighting...yes, the lights from the center roof console and doors; but not the white map/dome lights on the ceiling. The white map/dome lights inside the car DO go out. The red lights are so dim I actually didn't notice that they were on until I looked inside the car. They did NOT go out. They just stayed on. Based on my feedback I'm guessing you might be thinking it's one of the micro switches...but could a failing micro switch on the interior really cause the engine lid light to stay on? I know the answer is yes because electronics were made to frustrate me. lol They never went out. When I lock the car, initially everything (but the ambient lighting) goes out. Then the alarm beeps and all of the interior lights go on. After a while the white lights will fade but the ambient lighting will stay on. And so, too, does the light in the engine lid. It never goes out. All good thoughts. It might sound crazy but do you think it's possible that the dead turn signal bulb could somehow be causing this? I'm not sure whether it's a coincidence all of this started happening when my bulb went out or whether my bulb went out as a result of all of this other stuff. Sometimes a cigar is just a cigar...unless it's an electronic cigar, in which case all bets are off and anything can happen. -Eric

Huh. Ahhhh...maybe the "red led's" you are referring to are the interior infrared detectors. I've never noticed them glow before. It seems you have an alarm issue. First, the beep means an open zone somewhere. Maybe the engine lid since the engine compartment light stays on. Second, to disable the interior infrared detectors, double lock the car. See if the red led's you refer to go out. I do not think that the replacement of the turn signal bulb has anything to do with any of this.

I did a little self diagnosis last night (not much time mind you) but no matter what I did, I couldn't get the engine lid light to go off or find the source of the problem. I disconnected a number of electrical connectors and fuses but nothing cleared the issue. I'm sure I just need to spend more time with it -- I was in too much of a rush. Also, from what I could tell the ambient lights stayed on. Unfortunately, when I was done, like a bonehead, I disconnected the battery (not the bonehead part) and shut the frunk (completely -- yeah, that's the bonehead part) before walking away. So, now I've got to get juice to the switch through the fuse panel just to open it again. What a pain in the butt. lol At this rate, it won't be long before I throw my hands in the air and bring it to a local shop. I hate to do it but there's a good shop nearby and they work on Porsches so it might be worth the trip just to get the issue out of my hair (or what's left of it). -Eric

Hmmm, electrical gremlins in a 996. What part that goes out often commonly causes electrical gremlins? Might not be it, but it costs you $12 bucks and 20 minutes of time to find out.

Could also be related to the alarm control module under the driver's seat. Any chance it got wet? Spilled cup of soda or something?

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Okay, so what is that a picture of? I'm game for trying anything that will help me fix it and avoid a shop! lol I'm definitely going to replace the turn signal bulb, too. I know it won't be that but I've been shocked by stranger things. -Eric Supposedly a problem with the alarm should result in two chirps/beeps/whatevers from the alarm system rather than one. As for a spill, no chance. And since it hasn't seen rain in a while, it's not even like the water could have come in from the outside recently and I didn't wash it last weekend either. Out of curiosity, I felt around behind the backseat in case water might be getting stuck in from a clogged drain -- nothing. The alarm definitely thinks there's an open zone somewhere. The manual lists like 10 zones that could be impacting it from the trunk, doors and roof to the center console and door cubbies. But, what's really throwing me for the biggest loop is the fact that when I pop the engine lid from inside the car, the light on the dash illuminates showing that the lid is open. When I close the lid, the light shuts off...BUT the light inside the engine bay on the deck lid stays on. I wonder if the light unit itself is bad. Hmmm...but that wouldn't explain the ambient lighting inside the car staying on...although, who knows, if that's what's shorting out and throwing things into a tizzy. -Eric

Its the infamous Porsche/Audi/VW ign switch.

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Got it! Okay, so I haven't had any issues with the keys sticking or being hard to turn...but from the little I've read, it almost sounds like that might not matter. Is this something I should be able to pick up at a local NAPA or other part store or do an OE part? I did a quick search for the part and noticed that some sites say the replacement parts are not for models with "99634701707 updated lock housing." Do I have to open up my car to see if my switch has this part number or is there another way to know? -Eric

2004 uses the upgraded switch! The NAPA part number for yours should be: ATM 4B0905849 Please double check. You can also order online from Pelican, etc.

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That's the number I found as well. I stopped by AutoZone on my way home tonight. No dice. All sold out. I "reserved" one at my local NAPA store through their website but it says I've got to call the store to confirm availability. I'm betting it's not in stock. We'll see in the morning. I also checked Advance Auto parts' online search and came up empty. I'll call them in the morning, too. I know Pelican and other online stores are options but, if I can, I'd rather source the part locally so that I can work on it tomorrow night or this weekend without paying overnight shipping costs. So, here's what I noticed this evening. When I reconnect the battery, everything boots up and works properly. The engine lid light stays off. The little ambient lights in the doors and above the dash all stay off...until I lock the car. Once I do that everything goes haywire. Unlocking it doesn't reverse the issue. That's why I'm wondering whether the ignition switch could really be at fault here. Is power routed through the ignition switch even just by operating the alarm? In this case, I never even turned the car on. I did remove the light in the engine so that it wouldn't stay on -- it was building up a lot of heat by staying on like that. Anyway, hopefully, I'll be able to pick up a switch tomorrow and swap out the old one to see if that does the trick. I have my reservations but I really hope it works! -Eric

I've got a good direction... It's your front trunk latch microswitch. I know it doesn't make sense but at some point they started synchronizing the two lights in operation. If you had a scanner you could see what is triggering the fault beep. Alternatively, you could play around with the front latch, or perhaps unplug it? I know it's more expensive, but I am positive the ignition switch will not cure this issue

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Thanks, Dan. I actually found some threads on Renntech tonight that were leading me in that direction as well. I never knew the frunk and engine lid shared a circuit until tonight! According to one thread, the engine compartment light will go on when the frunk is open...which is consistent with what you've said. What's confusing me though is, if one of the microswitches is broken, wouldn't the "frunk/engine lid open" warning light on the dashboard be illuminated? Doesn't the car think one of those zones is open? Why would that light be dark? I wish I had the Porsche tool that would isolate the zone causing the issue. I'd rather not buy two new microswitches just to buy them. Do you think removing one of the two microswitches will isolate the problem even if they're both in the same electrical loop? I'm not sure what it will tell me. What makes you think it's the front latch microswitch and not the rear latch switch? As an aside, the hood opening mechanism hasn't been problematic at all. It pops up easily and the lever to release the hood catch isn't gummy. It all seems to work smoothly. The rear, however, strikes me as a little odd...although it could be perfectly normal. When I pop the engine lid, I hear the mechanism release but visually it looks like it's still closed. Does your engine lid pop out at all? I replaced my struts last year thinking that might help but it did nothing (oops). It's not impossible to open the lid but I have to really get my fingers underneath it to open it. -Eric

What frunk/engine lid warning light? On my 99 996 there is no such thing. I have made the mistake of releasing those and driving off, only to discover later that I left the damn thing open. The frunk lid pops up a bit, the engine lid does not....just sits there. But there is no warning/indicator light on the instrument panel for either. I even looked it up in my owners manual..no such light. I think you are on the right track with the microswitches.

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Sometimes people mistake the spoiler warning light for a trunk/engine cover open light.

When you say "The lights never go out'" Are they still on after ~1/2 hour? If not your condition may be normal. My 2003 has a frunk/engine cover open warning light.

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Huh. Interesting. On my '04 there's a light in the instrument cluster that comes on when the trunk and/or the engine lid is open. Here's a quick pic from the an '03 manual I found online. I drew a red arrow to the light I'm talking about. Interestingly enough, the light for the roof ("P" in the image) also seems to work fine. When I run the roof through the cycle of opening and closing the light goes on and then turns off as soon as the clam shell seals and the windows are in place. Nope -- not in this case. The spoiler light is "N" in the image and while that's not one of the zones the alarm seems to check, I haven't seen that one illuminate either. I'm talking about "O"...which lights up whenever I open the hood or the engine lid. Flip the switch, on comes the light. Close the frunk/engine lid, off goes the light. -Eric

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Good question -- I haven't waited 30 minutes but I'm going to say the light in the engine compartment never goes out. It's never been on with the lid closed before so I don't know why it would start staying on now. It shouldn't be on unless the trunk/engine lid is open...and they're closed/locked. ALSO, when I reattach the battery cables, the engine light is off (as are the interior ambient lights). When I depress the lock button, the engine compartment light goes ON...and that cannot be right...especially since it's never happened before. I don't know about the little ambient lights though since I've never waited 30 minutes. That said, I've also never noticed them staying on for more than a few minutes with the car empty and locked. And, the alarm is giving me a single beep which means it does think something's open. It's strange, right? -Eric

Well, chalk it up to "added features" difference frunk/engine light between my 99 and your 2004. Actually glad I don't have that annoying feature...just something else to go wrong. One quick question, is there any difference in what happens when you use the key fob vs. locking/unlocking with the key (manually)?

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I'm not sure I see the idiot light as an annoyance, especially since you can easily pop the engine lid and not be aware of it being open (since it doesn't actually pop up), but I don't think I tried unlocking manually vs. the key fob. Since I think the problem is unrelated to the doors I'm not sure it will make a difference but it's certainly worth trying. -Eric

Okay, now I'm completely stumped. I changed the faulty turn signal bulb. Out with the old, in with the new, lock the car to see the light flash and BAM...nothing. The bulb is still out. NOT good. When I lock the car there's still a beep like one of the zones is open and I still get an ongoing double-flash from the alarm system LED indicating that something isn't closed. I also tried locking and unlocking the car manually. Same thing happens. Here's another thing that's throwing me off. When I hook up the battery, shouldn't the frunk light go on since I've got the frunk open? The only way I can get it to go on is by locking it. I called a local shop to see if they can help -- I've got an appointment for Tuesday if I can't figure it out between now and then. Any other thoughts? -Eric

Sounds like you might have narrowed this down to a bad microswitch on the frunk lid locking mechanism, or maybe it just needs to be adjusted. And check the electrical connection there too. Yes, when you re-connect the battery the frunk light should come on because it is open. So I think the problem is there. That would lead to the open zone beep as well.

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Yes, that makes sense but why would my turn signal still be out and registering a failed bulb? Think it's the bad microswitch causing things to go haywire? Think that might just be an unrelated issue? -Eric

Unrelated and different. Try a different bulb, try swapping bulbs, re-seat the bulb, try re-seating the headlight assembly several times and clean the electrical connectors for the headlight assembly. Make sure you have the bulb mounted correctly in the socket.

"The rear, however, strikes me as a little odd...although it could be perfectly normal. When I pop the engine lid, I hear the mechanism release but visually it looks like it's still closed. Does your engine lid pop out at all? I replaced my struts last year thinking that might help but it did nothing (oops). It's not impossible to open the lid but I have to really get my fingers underneath it to open it." My '99 is the same...I don't know if this makes it "normal" or not...good luck with the light issue.

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My 01 does that, or at least doesn't pop up that much when released.

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Yup, the back of your mind went "what else is wrong" and it found something it didn't notice before.

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Okay, I went back to the turn signal. I noticed a little corrosion on the contacts so I cleaned them up and the new bulb now works fine. Old one was legitimately dead though, which is good. I guess everything seems to be pointing to the microswitch in the hood or engine lid. Since they're on the same loop I'm not sure how to isolate which one it is without a diagnosis tool. I hate the idea of buying a new switch only to find out the original was operating properly. -Eric

Well that is good...got the bulb issue fixed. I am not exactly certain about the lid microswitch operation but I think it is a simple go/no-go switch. I would test it with a multimeter for continuity. I know you will have to disassemble the front hood latch to get at the microswitch. Then disconnect the microswitch and put a multimeter with continuity on the connector leads, then operate the microswitch by hand to see what happens. One way it should be off, no continuity, and the other way it should be on, with continuity. If it does not function like that it is probably bad. $99 for a new microswitch is not really so bad. http://www.autoatlanta.com/porsche-p...section=803-00

Just try unplugging the front trunk switch (pull carpet back from front wall and unclip) and test to see if the lights go out and the double beep disappears. The double beep may stay (can't see frunk locked) but I assume all lights will go out. This confirms my belief

First of all, thanks for all of the great advice and suggestions and for hanging with me to help me track down this problem. I truly hate electronics. So, today, we found the culprit and I can confirm that we were all off track. Evidently Porsche did more than route the frunk and engine lid through the same circuit. They routed the glove box through it, too. It's funny because I was a click away from ordering the front microswitch over the weekend to fix the problem myself. I was back and forth between taking it to my indie shop and doing it myself. If it was a mechanical issue, I wouldn't have hesitated to tackle it myself. But with electronics...I really just don't like them. I would have gone through a process of elimination by replacing, first, the frunk microswitch, then the engine lid microswitch and then, I probably would have thrown spaghetti at the wall and just replaced the ignition switch to see if it could really be that simple. Never in a million years would I have looked at the glove box. It helps to have Porsche diagnostic software and a wiring schematic! lol Just my luck next week one of the switches I would have replaced will fail. lol -Eric

You didn't mention having a glove box!! My 99 996 doesn't have one so I never would have thought of that. Now we can add it to - if my car does this what the heck is wrong with it. Glad you found out what was wrong. Now back to the story.......

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I forgot the MkI cars didn't have a glove box. One less thing for you to worry about breaking, I suppose. -Eric

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Congrats on the fix! The part of your quote listed above is definitely true when it comes to the ignition switch - it should probably be considered a wear item and just be proactively replaced every 5 yrs or 50k miles. Sooner or later it will wear out, leaving you stranded probably at the most inconvenient time and place. As such, I don't think swapping it out during electrical gremlin troubleshooting is ever a complete waste of time and money - all $12 and 20 minutes that it requires. It's not a bad idea to keep a spare one in that glovebox along with the small flathead screwdriver tip it takes to change it out. On my 964, I used to keep a fuel pump relay in the glovebox for that very same reason.