Check dipped beam -- An odyssey of WTF (but it's now fixed)
08-02-2018, 02:09 PM
#1
Check dipped beam -- An odyssey of WTF (but it's now fixed)
(If you don't want to read long post, skip to question at the very end please)
One day I got the dreaded "Check dipped beam" which was a little vague but I found it meant the xenon bulb was out. After some research, I came up with a diagnostic path and discovered a few things to add to the (long) list that makes you go WTF regarding Porsche engineering
I pulled the headlight module and first discovered the harness wires literally crumbling in my fingers, leaving bare and shorting wires all over the place. Ordered two and while I waited...
With the headlight module out, I notice that on one side, the bolt which secures the front of the headlight tray was completely gone, on the other, it was out but somehow still hanging there. Fortunately, the metal bushing disk was present on both sides because it's kind of expensive. Got a new bolt and secured them. Always wondered why my headlights jumped around when I went over bumps...
Next, I swapped the xenon bulb to the other side. Lo and behold it worked and the known good bulb stopped working. Check bulb off the list
I almost left this step out because it was such a colossal failure, but it may keep others from wasting their time. I got a can of plasti-dip and tried painstakingly coating the many wires with some insulation. Yeah, that did not work. When I tried my creation, even more lights were out.
Once the harnesses came in, I replaced those. Headlights are now going haywire. All kinds of weird behavior, too long to list
It seems the harnesses weren't plugging in well. I didn't really want to go the route of clipping the plugs and inserting manually so I got some bulb lube and lubricated the rubber on the plugs and smeared a thin film over the contact holes.
Ahh, success...almost. Now the left high beam wasn't working, along with a couple other lighting issues. So I next checked the fuse (I know, it should have been the first thing but the harnesses needed to be replaced regardless). Fuse is cooked. Got some fuses and went through a couple before I decided to investigate further.
Pulled the left headlight out again and went to change the halogen high beam light. I discovered a lot more of the crumbling insulation at that wiring (along with some other wires I could see). This was causing a short and blowing the fuse. Problem is, I can't access these wires. The best I could do was lamely wrap some tape around the wires and hope for the best -- who knows how long that will last. Put the old bulb back in and...
Success!!! All lights now working...almost. I went to put the headlight wrench away in the back and noticed one of the license plate lights were out. So I got a phillips and took off the light. As I pull it out, it flickers on. Looking closer there's MORE OF THAT GD CRUMBLING INSULATION.
I was fed up with bare wires at this point so I just fiddled with it until the light came back on, grumbling to myself the whole time.
So, in the end, I have all lights working, some shoddily taped bare wires preventing a short, and apparently an entire vehicle of crumbling insulation with bare wires throughout just waiting to make my life a nightmare...I just shake my head going WTF...
I do have a question in all of this though:
Can I open up the headlight module in order to access some of the wiring inside so I can either tape it well or replace whatever harnesses that are available? This, as an alternate to buying a new headlight module for huge bucks.
_______________________________
2004 Cayenne S
One day I got the dreaded "Check dipped beam" which was a little vague but I found it meant the xenon bulb was out. After some research, I came up with a diagnostic path and discovered a few things to add to the (long) list that makes you go WTF regarding Porsche engineering
I pulled the headlight module and first discovered the harness wires literally crumbling in my fingers, leaving bare and shorting wires all over the place. Ordered two and while I waited...
With the headlight module out, I notice that on one side, the bolt which secures the front of the headlight tray was completely gone, on the other, it was out but somehow still hanging there. Fortunately, the metal bushing disk was present on both sides because it's kind of expensive. Got a new bolt and secured them. Always wondered why my headlights jumped around when I went over bumps...
Next, I swapped the xenon bulb to the other side. Lo and behold it worked and the known good bulb stopped working. Check bulb off the list
I almost left this step out because it was such a colossal failure, but it may keep others from wasting their time. I got a can of plasti-dip and tried painstakingly coating the many wires with some insulation. Yeah, that did not work. When I tried my creation, even more lights were out.
Once the harnesses came in, I replaced those. Headlights are now going haywire. All kinds of weird behavior, too long to list
It seems the harnesses weren't plugging in well. I didn't really want to go the route of clipping the plugs and inserting manually so I got some bulb lube and lubricated the rubber on the plugs and smeared a thin film over the contact holes.
Ahh, success...almost. Now the left high beam wasn't working, along with a couple other lighting issues. So I next checked the fuse (I know, it should have been the first thing but the harnesses needed to be replaced regardless). Fuse is cooked. Got some fuses and went through a couple before I decided to investigate further.
Pulled the left headlight out again and went to change the halogen high beam light. I discovered a lot more of the crumbling insulation at that wiring (along with some other wires I could see). This was causing a short and blowing the fuse. Problem is, I can't access these wires. The best I could do was lamely wrap some tape around the wires and hope for the best -- who knows how long that will last. Put the old bulb back in and...
Success!!! All lights now working...almost. I went to put the headlight wrench away in the back and noticed one of the license plate lights were out. So I got a phillips and took off the light. As I pull it out, it flickers on. Looking closer there's MORE OF THAT GD CRUMBLING INSULATION.
I was fed up with bare wires at this point so I just fiddled with it until the light came back on, grumbling to myself the whole time.
So, in the end, I have all lights working, some shoddily taped bare wires preventing a short, and apparently an entire vehicle of crumbling insulation with bare wires throughout just waiting to make my life a nightmare...I just shake my head going WTF...
I do have a question in all of this though:
Can I open up the headlight module in order to access some of the wiring inside so I can either tape it well or replace whatever harnesses that are available? This, as an alternate to buying a new headlight module for huge bucks.
_______________________________
2004 Cayenne S
08-02-2018, 06:18 PM
#2
The good news. This is very common and happens to most of the headlights and harnesses. The rest of the wiring harnesses in these cars don't seem to have many problems except for the areas where the main loom goes through the driver and passenger floorboards due to moisture and some pretty ghetto splice jobs at the factory.
The bad news. This is very common and there are no reasonable aftermarket fixes yet. Opening the headlight housing takes skill, patience, some special tools, and hours. People have done it, but no one is going to tell you it is easy. The cost of entry on a used Cayenne is cheap. The cost of upkeep is definitely not.
The bad news. This is very common and there are no reasonable aftermarket fixes yet. Opening the headlight housing takes skill, patience, some special tools, and hours. People have done it, but no one is going to tell you it is easy. The cost of entry on a used Cayenne is cheap. The cost of upkeep is definitely not.
08-02-2018, 11:11 PM
#3
Getting the headlights apart is a pain because the glue does not melt with heat. You can remove the ballast/CU on the bottom to improve access and use a long paintbrush and liquid electrical tape to repair the insulation and prevent shorts.
08-03-2018, 08:54 AM
#4
The good news. This is very common and happens to most of the headlights and harnesses. The rest of the wiring harnesses in these cars don't seem to have many problems except for the areas where the main loom goes through the driver and passenger floorboards due to moisture and some pretty ghetto splice jobs at the factory.
The bad news. This is very common and there are no reasonable aftermarket fixes yet. Opening the headlight housing takes skill, patience, some special tools, and hours. People have done it, but no one is going to tell you it is easy. The cost of entry on a used Cayenne is cheap. The cost of upkeep is definitely not.
The bad news. This is very common and there are no reasonable aftermarket fixes yet. Opening the headlight housing takes skill, patience, some special tools, and hours. People have done it, but no one is going to tell you it is easy. The cost of entry on a used Cayenne is cheap. The cost of upkeep is definitely not.
I wonder if it happens at the tail light harnesses too.
It boggles the mind that, after decades of cars being made, they didn't know in 2004 what good wiring insulation was. I mean...really...I haven't seen that kind of degradation in any other car, including way older ones like my 88 Samurai
Good to know. Is taking off the CU pretty easy? Might have to order some liquid electrical tape...
08-03-2018, 10:20 AM
#5
Nordschleife Master
This problem happens way too frequently on a car that costs this much. Gotta love Porsche quality!? When this happens to me and it will, I won't waste my money on the crap Porsche replacement parts and will rebuild the harness myself. If I can rebuild a engine harness on a 928, I can definitely do the headlight harness on a Cayenne. lol
Good job on working the problem! Sometimes it can be hard to have patience and the problem ends up working you, if you know what mean... lol!
Good job on working the problem! Sometimes it can be hard to have patience and the problem ends up working you, if you know what mean... lol!
08-03-2018, 12:21 PM
#6
I know there were some mid 90's mercedes that are notorious for the entire engine wiring harnesses doing this too. Don't ask how much fun that was to deal with.
08-03-2018, 02:39 PM
#7
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It isn't a matter of $$. It's the power of the Green movement in Germany (and other countries in Europe) - this sort of problem was seen early on with Volvo DL5's in the 70's - where the engine harness would break down, and things like the engine starting all by itself in the middle of the night happened. Some manufacturers in trying to avoid using fossil-based insulation (plastic) used an insulation made from soybean oil. That not only deteriorated on its own but also attracted vermin that would make it dinner. I haven't heard of this on the 958's - yet...
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08-06-2018, 07:49 AM
#8
I used to think "bio-degradable" harness was a joke, but then I discovered it was not - the manufacturers indeed tried to go green and design harnesses that would bio-degrade in a landfill after the vehicle's useful life. However, the early ones started degrading far before the vehicles were done.
09-30-2018, 01:51 PM
#10
UPDATE: The fuse blew again. Ordered some liquid elec tape. Checked both headlights internals for bare wires. One headlight was OK (wire insulation was brittle but since I didn't handle the wires, it was intact). Second headlight was the one where I had checked the halogen bulb earlier in the story, and by moving the wires, the insulation had disintegrated (lesson: if you move that wiring around, do it VERY minimally and gently). My shoddy electrical tape fix had failed and shorted a wire.
So I put on about 3 coats of liquid elec tape while keeping the wires separate. It was kind of a sloppy job but coverage was more important than aesthetics. I looked around in there but only had bare wires inside the halogen bulb access area. Put it all back together and it now works...once again...
Hopefully this one sticks
So I put on about 3 coats of liquid elec tape while keeping the wires separate. It was kind of a sloppy job but coverage was more important than aesthetics. I looked around in there but only had bare wires inside the halogen bulb access area. Put it all back together and it now works...once again...
Hopefully this one sticks
10-02-2018, 11:36 AM
#11
If you have to open it back up again...
I ended up snipping every internal wire inside my headlight assemblies and sliding heat shrink tubing all the way down the wire. After shrinking that I then soldered the wire back together and shrunk heat shrink tubing over that connection. I did not disassemble the headlight; I just did it all from the back cover. Some of the factory wire routing in the assembly was unnecessary, causing friction and making it difficult to slide the heat shrink tubing down the wire. I pulled those wires out of the channel one at a time after snipping and never put them back in the channel. I did both headlights in one night and then used compressed air to blow all the insulation flakes from the front of assembly.
If I had to do it again it would be faster to use 100 pack of solder seal connectors for $13 and Wagner Furno 750 Adjustable Temperature Heat Gun for $59. For solder melting step I set the Furno to 550 degrees and use the back-blocking heat-focusing adapter included in home depot packaging. You may want to hold additional protection like a magazine between what you are heating to solder melt and the rest of the headlight internals.
I ended up snipping every internal wire inside my headlight assemblies and sliding heat shrink tubing all the way down the wire. After shrinking that I then soldered the wire back together and shrunk heat shrink tubing over that connection. I did not disassemble the headlight; I just did it all from the back cover. Some of the factory wire routing in the assembly was unnecessary, causing friction and making it difficult to slide the heat shrink tubing down the wire. I pulled those wires out of the channel one at a time after snipping and never put them back in the channel. I did both headlights in one night and then used compressed air to blow all the insulation flakes from the front of assembly.
If I had to do it again it would be faster to use 100 pack of solder seal connectors for $13 and Wagner Furno 750 Adjustable Temperature Heat Gun for $59. For solder melting step I set the Furno to 550 degrees and use the back-blocking heat-focusing adapter included in home depot packaging. You may want to hold additional protection like a magazine between what you are heating to solder melt and the rest of the headlight internals.
10-02-2018, 11:54 AM
#12
If you have to open it back up again...
I ended up snipping every internal wire inside my headlight assemblies and sliding heat shrink tubing all the way down the wire. After shrinking that I then soldered the wire back together and shrunk heat shrink tubing over that connection. I did not disassemble the headlight; I just did it all from the back cover. Some of the factory wire routing in the assembly was unnecessary, causing friction and making it difficult to slide the heat shrink tubing down the wire. I pulled those wires out of the channel one at a time after snipping and never put them back in the channel. I did both headlights in one night and then used compressed air to blow all the insulation flakes from the front of assembly.
If I had to do it again it would be faster to use 100 pack of solder seal connectors for $13 and Wagner Furno 750 Adjustable Temperature Heat Gun for $59. For solder melting step I set the Furno to 550 degrees and use the back-blocking heat-focusing adapter included in home depot packaging. You may want to hold additional protection like a magazine between what you are heating to solder melt and the rest of the headlight internals.
I ended up snipping every internal wire inside my headlight assemblies and sliding heat shrink tubing all the way down the wire. After shrinking that I then soldered the wire back together and shrunk heat shrink tubing over that connection. I did not disassemble the headlight; I just did it all from the back cover. Some of the factory wire routing in the assembly was unnecessary, causing friction and making it difficult to slide the heat shrink tubing down the wire. I pulled those wires out of the channel one at a time after snipping and never put them back in the channel. I did both headlights in one night and then used compressed air to blow all the insulation flakes from the front of assembly.
If I had to do it again it would be faster to use 100 pack of solder seal connectors for $13 and Wagner Furno 750 Adjustable Temperature Heat Gun for $59. For solder melting step I set the Furno to 550 degrees and use the back-blocking heat-focusing adapter included in home depot packaging. You may want to hold additional protection like a magazine between what you are heating to solder melt and the rest of the headlight internals.
