25 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHBrake Light Problem
Leading reported evidence
Check bulbs
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Leading evidence: 'Check bulbs' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'brake light switch' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check bulbs' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed · Original poster
I had already cleaned the contacts, which didn't show any corrosion, so this had me trying to find another problem that didn't exist.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Performed · outcome unconfirmed
I also replaced few brake switches hoping to find problem there, but it was not my luck.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Performed · outcome unconfirmed · Original poster
I replaced the GE 1077 bulbs with Sylvania 7528s, which are about 0.050" larger diameter.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that suspect a cause
1
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0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suspected cause · Original poster
All of this made me think that the problem was with the brake light switch, but a new one didn't solve anything.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Suggestion
Check the lamp sockets for corrosion, also make a test light by soldering a wire to the ground and another to the power lug on an 1141 or other single filament bulb.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
Check the lamp sockets for corrosion, also make a test light by soldering a wire to the ground and another to the power lug on an 1141 or other single filament bulb.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
25 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
4 acknowledgements have no verified action link; they do not establish a repair result.
Outcome without a verified action link
All of this made me think that the problem was with the brake light switch, but a new one didn't solve anything.
Need some help boys, can't figure this one out. Center brake light is working, but neither the left or right brake lights are. According to the wiring diagram (if I'm reading it right) there is a single wire from the brake light switch to the CHL and 'regular' brake lights. There appears to be a plug somewhere where the feed split to the different lights. Not sure where this junction is, but it seems like this might be where the problem is. Anyone know where this thing is located, or do I need to look elsewhere?
The transmission was out a little while back for a RMS/IMS job, maybe it is in a location where it could have been disturbed, but I don't know.
As always, guidance is appreciated.
Yes, the other lights seem to function normally. Looking at the verion of the shop manual which has been available on line.
Also, guess the year would help too... 1999 C2.
Thanks Kazual. I spent about 15 minutes looking at it yesterday, but having already had a few pale ales, I figured it was best to to crawl under the car and look around. Maybe I'll do it today when I get home from work.
OK, have spent a little time trying to solve this, but still no love. Driver side brake light illuminates, but not as bright as a brake light should be. Passenger side will not light up even though it shows 11.65 volts. Turn on the headlights and the working incandescent light goes out, plus the cruise doesn't work with the lights on. All of this made me think that the problem was with the brake light switch, but a new one didn't solve anything. The tail lights and brake lights share the same ground, so I don't think that's the problem. I do realize that the headlight switches on these cars do fail, but don't see how this would effect the brake light circuit.
Any ideas as to what I'm missing?
that is very interesting, I would try to swap out the ignition switch... a bad switch is prone to electrical anomalies w/o any signs of logic... though this is the first Ive heard for brake lights not working w/o a light at the dash... this is certainly an anomaly... verify that your light bulb is working when you first turn the key on or pull a brake bulb out... this should turn on the brake dash out.
The ignition switch is cheap enough and 15-30min.... fix.... Im reaching here but worth the shot.
I feel like it's a ground too, but don't know. I have not checked to see if the CHMSL on the spoiler is working, but that's easy enough. Also thinking that I should disconnect the headlight switch and see what happens. The one other thing that has just occurred to me is that I did install LED license plate lights a little while back. Not sure how this could effect anything, but I have seen LEDs cause weird things. I'll pop them out this afternoon and see if that makes any difference.
I appreciate the suggestions.
Bad ground possible. You mention you are getting voltage, but possibly not enought current to light the bulb. Check the lamp sockets for corrosion, also make a test light by soldering a wire to the ground and another to the power lug on an 1141 or other single filament bulb. You can use this tool to check current for all kings of automotive applications. Voltage only tells part of the story, often current is more important.
The bad grounds have been found and the problem is solved. The base of the bulbs were a little loose in the socket and would only pass enough current to light the small tail light filament, but not enough for the brake light filament. I replaced the GE 1077 bulbs with Sylvania 7528s, which are about 0.050" larger diameter. I had already cleaned the contacts, which didn't show any corrosion, so this had me trying to find another problem that didn't exist. Naturally, I discovered the source of the problem after pulling the interior quarter panel and carpet to check all of the connections there...
Thanks again for the advice.
Great, that I have found this topic, I have exact the same problem with my 966C4S. Is there any chance you remember what exact location was this issue on your car? Is there grounding point under some panel in interior?
Thank you in advance, hope you still having fun with Porsche's
I have had the 1157 style bulbs blow the filament at one end, then the filament drops and fuses to the tail element of the bulb, still has continuity, but no light..
in some cases it will cause the marker lights to flasher so faintly...
Thank you for suggestion. In my case, I have already checked bulbs. In addition I get ABS/PSM error and sometimes my center brake light is glowing when brake is not pressed, so it will be definitely bad grounding somewhere, and I hope someone can help me to point directly, where brake light grounding is located at interior.
I also replaced few brake switches hoping to find problem there, but it was not my luck.
And this is 996 Carrera 4S, but I believe other 996 has similar grounding point layout.
Yep I was just sharing tiny issues that will have you screaming in the garage.. LOL
I find the bulbs with the oval contacts on the bottom , seem to play nicest with Bosche/German sockets..
I have not found a ground lug diagram for the 996, it used to be common on the old bug manuals since they were considered a annual service item.
Hey there, were you able to find your grounding issue? I'm having a similar issue. Also, if measuring for Voltage and Current, what should be expected to see when measuring current? Thanks!
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