Brake Light Switch Failure?
12-22-2002, 07:52 PM
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Brake Light Switch Failure?
Been lurking and learning for a while. Just bought a '87 Carrera,Guards Red with front and rear spoilers. Really enjoying the Porsche experience.
Need some help...The brake lights only come on when the brake pedal is pressed very firmly. Light braking does not activate the lights. Using a Haynes Repair Manual I tracked down the brake light switch. It was not mounted under the floor board as stated in the manual. However the supplement to the manual led me to the master cylinder. Its mounted on the master cylinder with no adjustments. The car has a firm pedal and is braking well. Is it possible the switch is just going bad and thats why it is only working with heavy braking? Suggestions to remedy the problem will be appreciated.
Matthew
Need some help...The brake lights only come on when the brake pedal is pressed very firmly. Light braking does not activate the lights. Using a Haynes Repair Manual I tracked down the brake light switch. It was not mounted under the floor board as stated in the manual. However the supplement to the manual led me to the master cylinder. Its mounted on the master cylinder with no adjustments. The car has a firm pedal and is braking well. Is it possible the switch is just going bad and thats why it is only working with heavy braking? Suggestions to remedy the problem will be appreciated.
Matthew
12-22-2002, 09:30 PM
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Matthew,
First, ditch the Haynes book - Get the Bentley 84-89 Carrera book, typically around $75 (list $119) through internet sources (just looked at one search engine and, for example, buy.com has it for $76).
You can replace the switches individually, last time I replaced them I replaced both of them. The Porsche part number for the two pole switch is 113.945.515.H. I buy some of my Porsche parts from Reeves Porsche in Tampa as they discount 25% (mention mail order prices), and some also like to use Sunset in Oregon as they charge cost + 15% (mention Excellence discount), which is about the same as Reeves. On the brake light switches, your best price actually would be through a VW dealer or VW parts source. Some have suggested avoiding the aftermarket brake switches made in Brazil, however, I don't have any first hand experience with those.
First, ditch the Haynes book - Get the Bentley 84-89 Carrera book, typically around $75 (list $119) through internet sources (just looked at one search engine and, for example, buy.com has it for $76).
You can replace the switches individually, last time I replaced them I replaced both of them. The Porsche part number for the two pole switch is 113.945.515.H. I buy some of my Porsche parts from Reeves Porsche in Tampa as they discount 25% (mention mail order prices), and some also like to use Sunset in Oregon as they charge cost + 15% (mention Excellence discount), which is about the same as Reeves. On the brake light switches, your best price actually would be through a VW dealer or VW parts source. Some have suggested avoiding the aftermarket brake switches made in Brazil, however, I don't have any first hand experience with those.
12-22-2002, 11:34 PM
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Bill...Appreciate the feedback. I only see one switch on the master cylinder and its mounted on the inboard side behind the booster. Is it possible the '87 has only one? It is two prong. Are you in agreement that the switch is probably bad?
Matthew
Matthew
12-23-2002, 01:44 AM
#4
Mine did that (81) and the switches (2?) were replaced. They do fail regularly. Some also say a good brake bleed helps that too, but mine still sucked. 2 switches = no problems now. The bits and pieces and labor (if needed) is cheap enough not to even warrant discussion. This is a safety issue.
rjp
rjp
12-23-2002, 08:22 AM
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[quote]<strong>I only see one switch on the master cylinder </strong><hr></blockquote>
Matthew,
Interesting that you've only got one switch, usually there are two, one for each of the braking circuits. Since this symptom is a pressure symptom, there's nothing else in the braking circuit that utilizes pressure to activate the brake lights, ie, no switches that might be adjusted.
Matthew,
Interesting that you've only got one switch, usually there are two, one for each of the braking circuits. Since this symptom is a pressure symptom, there's nothing else in the braking circuit that utilizes pressure to activate the brake lights, ie, no switches that might be adjusted.
12-23-2002, 10:10 PM
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Bill...There were two switchs just as you said! Just needed to move a duct out of the way. Replaced both switchs,bled the system and all is well. Thanks
Matthew
Matthew
