Electrical fault - 987.2 left-turn signal.

First - I'll tell you where you can find the bulb - an HY21W (German bulb) - your friendly local Volvo dealer. They used it in the V40,50,60,etc.. and they used it as a turnsignal bulb. If you go to your Porsche dealer they'll lookup the PN: 999-631-305-90, and they'll tell you they don't have it and it will take at least 3 business days to get it, and possibly more. And it costs $23.00. This is not a bulb that looks like it should cost $23 - but.. that's what they wanted. So I came home bulbless... this isn't totally critical since at some time I had programmed the front module to flash the side markers (while remaining side markers, just a bit dimmer) with the turn signals. That was still working, and I vaguely remember seeing an error code about the turnsignal some months ago the last time I scanned the car.... so it's been that way for a while, but the side marker seemed to work OK. No one yelled at me for not signaling. Being OCD - on the way home from the Porsche dealer, I stopped at a local AutoZone where a semi-brain-dead youth was manning the register. I asked him about a bulb for a 2009 Boxster , PDK , base, he looked on the computer for a while, went away and came back with a 2 pack of suspicious-looking bulbs. Since I'd never actually seen the bulb, I bought them just on the chance they were the correct bulbs. Of course they weren't. Hi Kids - which of these doesn't look at all like the other? Oh - both. Pulled the "bad" bulb from the light assembly. It's an HY21W, I forget what the Sylvania one is - but every damn big-box website I went to (Autozone, NAPA, Advance Auto), and the Sylvania website - listed that same damn bulb for our cars. Sylvania is owned by Osram who made the bulb on the right. What's wrong here? Anyway - I was getting nowhere in finding the bulb, so I Amazoned it - two for $15, free delivery on Saturday. Ordered. But I noticed on one of the Amazon listings for it, it also included various Volvo models.. So that's how I found a new bulb - HY21W - at Volvo. It was still $22 with tax, but they had it there and to me, that was worth the premium. And they were quite friendly and wanted to chat about the Porsche. I headed home with my treasure, got out my headlight removing tool, did the funky twist/klunk, pulled out the headlight, opened the little porthole in the side of it to access the bulb, and installed the new bulb. Happily, I reinstalled it.. And it made no difference - it's still not working. Just for giggles, I tossed my Ohmmeter on the old bulb - and it read 2.1 Ohms so it was good. The problem isn't the bulb. I used my Foxwell NT530 to diagnose things, and sure enough, it turns up an error on that bulb. The right side looks fine, left side - no light/no-blink. Funny thing - the blinker remains normal speed, there is no dashboard error message, just the stored code and no light. Tomorrow it comes out again, and a bit more exploration and cleaning. Have to look carefully at the connector for the light to the wiring harness in the car, since that's done when the light is pressed home in the mount. Will be cleaning and looking at it. If anyone has ideas - I'm all ears. Anyone BTDT and fixed it - that would be wonderful. Googling it makes it seem that this is a rare failure - no reports of it that I can find. According to ALLDATA's wonderful interactive color-coded wiring guides - there is just one wire from the front module that goes to it, and it has another wire going to ground (under the headlight mount apparently.) I'll update tomorrow. Remember left bulb = No buena, right bulb = OK. Take it in to the parts guy at Volvo he'll help you out.. BTW - this getting old stuff sucks. I know it's somewhere, but I can't find my Foxwell NT710. Could it be in the Cayenne? I can't find it in my office or the adjoining (and somewhat messy) garage... it's in a case for Dogs sake! Oh - something cool Porsche did on the headlights. There are access ports for various bulbs on the headlight assembly. If you look closely at the body of the light next to the access port, the type of light is molded into the plastic. HY21W. Go figure. Clever idea.

I doubt the bulb is the problem, but to prove it you could swap the left and right bulbs. I'd investigate the ground. Might be some corrosion somewhere. Does the ground go through the headlight connector along with the power connections, or does it just ground through contact to the chassis?

Looks like the kid looked up the "rear" turn signal bulb...

The entire light housing is plastic so the ground must be going through the connector. Very odd that its not fast flashing. Does it fast flash if you leave the bulb out?

No - he looked up the front. It's their bulb guide (which appears to by Sylvania's bulb guide) that's wrong.. and every damn parts store refers to that and gives a blank look when it's pointed out that it's wrong.

More now.. fixed. But how did I get there? I started out by taking out the light assembly and carrying it to my office desk with a nice towel under it, so I could disassemble it and check things out. One note - I decided to see if the turn-signal would fast-bliink with the entire light assembly removed. Nope. Normal blink rate. No error messages on the dash. Apparently despite the module knowing (via Foxwell ) that there was a bulb out - that still doesn't trigger any warning for the driver. Sort of a miss on the part of Porsche IMHO. OK, being me - I decided to start at one end (the bulb) and work my way backwards. The socket for the bulb disconnects from a wire/connector that disappears into the guts of the headlight assembly. It's easy enough to get apart. Socket Assembly - sans bulb I took out the bulb (new one) and just checked the resistance so I had a reference number. Somewhere between 1 and 2 Ohms, across the contacts on the bulb. I took the socket and cleaned the contacts to the wiring harness, and then cleaned the socket. It actually appeared perfectly clean, but I had some MAF cleaner hanging around, so each of those got a squirt, as did the connector on the wire going into the guts of the headlamp. I back-probed the connector going to the socket and got my expected less than 2 Ohm reading. Socket - I used a tiny jeweler's screwdriver to very slightly bend the shell a bit inward to make absolutely certain I had good conductivity to the bulb. Arrow where I bent.. The bulb/socket got reassembled and back in the housing, and I decided to try to see if I could determine what contacts on the light/harness connector were for the turn-signal. So I looked into the connector. Imagine my surprise (and a bit of delight) to see: Well - duh. Happily - the pin was able to be straightened back into position with a bit of fiddling. I imagine if this happens again I'll be looking at replacing that pin or jumpering around it (neither look fun to do.. but it's an old car..) It all works now. I have a blinker on the left-front. I have no idea when this happened since I can't recall having the headlight out in the near past, and beyond the near past is lost to the mists of time.. I have taken it out a few times to swap low-beam LED bulbs around.. so I'm sure it was me, and I guess if I checked my Amazon order list I could give you an idea on how long it's possible to drive around without a front turn-signal and never know it. Just another fun adventure in 987 ownership. What did we learn? The turn-signal bulbs are actually quite long-lasting. Sylvania is not to be trusted as a reference source for replacement bulbs. Amazon is the cheapest source, but in a pinch, a Volvo dealer is good to have around. Be careful reinstalling the headlights - it's a fiddly business, no matter what, and this one seemed particularly so. Sometimes it IS the simple things. This got way more complicated than it should have. The connector should have been the first thing I checked, but I'm not built to check the obvious first, I need to follow the garden path to enlightenment. Thanks all for the helpful suggestions.. My detailing kid is due soon to pretty the car up for a Concours on Sunday.. I'm hoping for "Best 10-footer".. (closer than that they might notice some warts - but it does have almost 80,000 miles on it..) It should be fun. If you're in the area it's at Porsche Monmouth, 9AM-noon (being me, I'll probably arrive around 10AM..)

Just read the thread, Don - great write-up. Nice you got it sorted, but don't beat yourself up for a moment. Usually those pins in those connectors don't seemed to get jammed and I'm kind of puzzled as to what might have misaligned one in the first place. Nice work.

Your writeups are always entertaining!

Having just changed out all of the bulbs in both front and rear light housings for LED , I learned quite a bit about what the car needs and what doesn’t work. Took a lot of research and time to get the right combination of bulbs. Some needed CANBUS resistors to eliminate error messages, while others were simple bulb swaps. Ordered and returned numerous bulbs from Amazon to get the correct results. Beware of the descriptions if going that route. Some claimed to be CANBUS ready, but actually were not, giving an error message. Returned those and found some that had built in resistors which cleared up the problem. In the process of doing this I was scratching my head when replacing the reversing bulbs and put one LED bulb in and put the car in reverse with the key in the ACC position and saw the results of a much brighter output on that side as compared to the feeble glow on the other. Thought looks great, time for the other side. Swapped out that bulb only to have neither side light up. Returned those and ordered fro m another maker, whose description stated that they were CANBUS ready and had the correct results. Reinstalled the light housings to check the looks on everything and had one of the taillights not function. Had to take both housings apart again and found it to be just bad contact between the bulbs base and the socket. Removed all the bulbs and sprayed all of the sockets and bulb ends with ‘Electrical Contact Cleaner’ and used a tiny screwdriver to straighten and realign some of the contact blades in the socket bases. All good now, and the clarity and brightness is a great improvement over the stock halogen. Especially like the reversing bulbs as they perform like miniature headlights when backing into my driveway and garage after dark.

Hey WTF Chuck, The LED 's look sharp, I'm hoping you can share where you, ultimately, found the correct LED 's? I have Lasfit on my truck and no problems. I was wondering if that was your go-to?

Just a FWIW, I used a kit that had every bulb that can be changed except driving bulbs from either Amazon or AliExpress . Every bulb worked first time, no polarity issues (uses a clever bridge circuit that provided the correct polarity for the led bulb and provided the circuit path needed to satisfy the bulb monitors). Every one works. No errors, no resistors, simply plug and play. I know I posted this a few months ago when I installed it, with the vendor info, so a search should turn that up.

It took a bit of research, about bulb bases, resistors, error messages and which were actually CANBUS ready. And I used Amazon since they had the biggest selection, but did end up returning some which did not meet their claims of being error-free. The following pics show what I ended up with in the long run and I’m very happy with the result. I feel like the vehicle looks much more modern, up to date, over the yellowish halogen OEM bulbs. The side marker and parking lights did need resistors since the tiny size of the bulbs do not allow for an on-board resistor, I assume. Any questions, I’ll be glad to reveal what I encountered during this project.

Thanks for digging this up!

Forgot to add the resistors I used for the side marker and parking lights. Tapped into 12V and Grd at connectors. Without the CANBUS resistors I was getting an error message to ‘Check Side Marker’ and ‘Check Parking Light’.