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Non Functioning Third Brake light

mattprice693

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Joined
2 Sep 2021
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4
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.
 
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
 

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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.
 
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.
 
YPVS said:
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.

I don't own a multimeter unfortunately so it looks like a trip to the Specialist coming on. :nooo:
 
mattprice693 said:
YPVS said:
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.

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

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

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