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Alarm problems since harness recall


19 Feb 2004
My 95 C4 Cab was in at the OPC on Friday for its new wiring harness, and since then the alarm has been going off for no apparent reason. It is a 3rd party alarm (Laserline) though I assume they are all much the same, and its diagnostics seem to suggest a problem with the interior movement sensor.I will be trying to get OPC to take a look, though I suspect they may plead ignorance of any non Porsche equipment. But how likely is it that the wiring harness replacement could have disturbed the alarm wiring - ie does the engine wiring loom extend into the cabin, or does the alarm wiring extend into the engine compartment ?I suspect this is going to be a pain to resolve due to its intermittent nature - it can be fine for several hours and then keep going off - just when we and the neighbours are trying to get to sleep !

Migration info. Legacy thread was 17419
Not Replying to this message, but I noticed you posted one back in April re your brake pressure light coming on. My Turbo 993 has the same problem - often goes out when re-starting... Did you find out what the problem was?

Many thanks.

Richard Sutton

Migration info. Legacy thread was 20953

Off topic I know but to answer your Q. all C4's and turbo's have a diffrent way of pressurising the brake system. The C2's have a vacuum pump. According to my specialist this is perfectly normal (Assuming it's only staying on for less than 30 secs or so that is)- mine does it too.

Takes longer to go out in colder weather too.



Migration info. Legacy thread was 20956
It (the brake light, not the alarm) still stays on very occasionally (with no sign of eventually going off), and always just turning the ignition off and on briefly cures it - I do it while moving so I can just bump start the car.

Re the alarm post (in case anyone is interested), it seems to have settled down. I can only summise that having the battery disconnected for the 5 hour harness recall job, upset the movement sensor in some way.

Migration info. Legacy thread was 20957
Check the little sensors are not flapping around loose. Very rarely my windscreen sensor comes a little loose and sets off the alarm.

Cabin air blower intakes can set some alarms off unless closed.

They used to provide really cheap ultrasonic sensors which very expensive alarms, which meant they needed replacing after a few years. Not sure if this is still the case.

Migration info. Legacy thread was 20960
The engine loom recall only affects the engine bay. no work is carried out in the cabin.

Migration info. Legacy thread was 22019

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