911uk

Non Functioning Third Brake light

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6 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis

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YOUR RESEARCHNon Functioning Third Brake light

Leading reported evidence

Replace into the clam shell neither work

Performed · outcome unconfirmed

No successful repair reported for this finding.

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Reported fixes: 0
Unsuccessful attempts: 1
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Performed · outcome unconfirmed · Original poster
Apart from the fact that the internals of the unit itself are shockingly low quality for a Porsche, each unit works in the spoiler raised position but when they're swapped into the clam shell neither work.
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Non Functioning Third Brake light

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Leading evidence: 'Replace into the clam shell neither work' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace into the clam shell neither work' (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.

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Use wiring diagram, if you could find out what wires

Suggestion or failed attempt

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Reported fixes: 0
Unsuccessful attempts: 1
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Discussions that contain suggestions: 1

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Suggestion
Using a wiring diagram, if you could find out what wires on the connector of the spoiler harness, then put a meter across for continuity at the plug, with spoiler up and down, it would confirm either working sensor or broken wires/sensor.
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Non Functioning Third Brake light

Frequently discussed actions (2)

These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.

Replace into the clam shell neither work

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

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
Apart from the fact that the internals of the unit itself are shockingly low quality for a Porsche, each unit works in the spoiler raised position but when they're swapped into the clam shell neither work.
Original post Read captured discussion
Non Functioning Third Brake light

Use wiring diagram, if you could find out what wires

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

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.

Suggestion
Using a wiring diagram, if you could find out what wires on the connector of the spoiler harness, then put a meter across for continuity at the plug, with spoiler up and down, it would confirm either working sensor or broken wires/sensor.
Original post Read captured discussion
Non Functioning Third Brake light

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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.

6 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.

911uk: 1 discussions

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0 acknowledgements have no verified action link; they do not establish a repair result.

Generation: 20261026T183130Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

I've searched the forum and can't seem to find the answer. My C4S Cabriolet has a non working third brake light in the clam shell. When the spoiler is raised the one there works. I've swapped the light units around and they both work in the raised spoiler position. Any ideas where I might check? No warning lights on the dash by the way such as spoiler or PSM. Thanks in advance Math.

POST 2Original post

I am a little unsure if it the same style brakelight that I have had issues with ie a thin strip containing multiple bulbs but having looked at mine I did consider soldering the bulbs in place. Of the ten or so bulbs all seem to work and the issue really seemed to be the connections were not that robust. In short once I took it out and connected it up and prodded the bulbs they all seemed fine. Pip

POST 3 / ORIGINAL POSTEROriginal post

Thanks for the reply. Apart from the fact that the internals of the unit itself are shockingly low quality for a Porsche, each unit works in the spoiler raised position but when they're swapped into the clam shell neither work. At a loss at present.

POST 4Original post

I'm pretty sure one of the microswitches in the spoiler drive gearbox enables and disables the clamshell light in relation to where the spoiler is. The other 2 sensors are to signal the end position of the spoiler. Using a wiring diagram, if you could find out what wires on the connector of the spoiler harness, then put a meter across for continuity at the plug, with spoiler up and down, it would confirm either working sensor or broken wires/sensor. The wires do get brittle up there.

POST 5 / ORIGINAL POSTEROriginal post

I don't own a multimeter unfortunately so it looks like a trip to the Specialist coming on. :nooo:

POST 6Original post

Or spend under a tenner on Ebay and arm yourself with a must have tool?

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