Hi Guys,

First time post. To say my issue is bizarre and hard to diagnose would be a bit of an understatement. Here's the deal.

My 2002 996 CS4 appears to have some type of short when the tempature rises outside. I live in Southern California so it can get kind of warm. So here is basically what happens.

Issue 1: My car can be sitting parked and will randomly just honk. Two quick honks.

Issue 2: I can be driving the doors will lock & unlock, the center dash light will flash and the car will honk (two quick honks). It is random how often it does this, sometimes 20 times in 10 min's sometimes once in an hour. There doesn't appear to be ANY pattern.

Issue 3: Which may or may not be related to issue 1 & 2 has to do with the automatic windows. Basically when you open the door the window comes down slightly.. this feature has become very sparatic.

I have removed the circuit breaker for the horn but that does not seem to have mattered at all.

All three issues appear to somehow be related to the heat as the car never randomly honks in the morning or the night.

Any ideas would be awesome.

 

Typically honking twice indicates a problem with the alarm control module. If it only honks once, it indicates that something is open (center console lid, door, etc.). This shouldn't be heat realted, but I'm not sure. It sounds like your module is failing or has a short that is causing the issue. Perhaps heat aggrivates it if it's a short.

The automatic window issue is most likely a seperate issue. The window should consistently lower to clear the rubber molding when you open the door. If it completely stops retracting, then it's probably a window regulator that needs to be replaced. If it's sporadic, then it could be a microswitch for the window control. Both are fairly common issues.

The only way that I could see them being related is if the microswitches are bad or shorting out, and this is somehow causing your alarm system to think there's an open circuit somewhere.

It's an interesting issue...

 

+1

BINGO!!

P.S. A quick fix may be as simple as disconnecting your battery (have your radio code in hand) for a few minutes. This may reset (or kick start, if you will) the microswitches. Good luck.

 

I installed an after market stereo / nav when I first purchased the car. Could this be causing some of the issues with the horn?

 

Yes - if the radio is not correctly grounded, the horn will sound if you put your alarm on. On the left side of radio, you need to put tape on the side of the new unit to break the contact with the lever on the side of the car.

BTW - for your other problems (which I don't think is related to the radio ground) you might just try swapping out your battery for a new one. If its old, and can't keep a good charge, there are a bunch of random things that happen like windws going up and down, etc.

Not sure if you have a cab or not, but if you do, check your remotetop if you have it installed. It controls the windows some, is connected to the locks, etc.

 

Thanks guys, you gave me a lot of ideas of where to start!

 

Ok there is a lot going on in this post, so I would like to attempt to add some info and ask some additional quesitons.

The beep you are hearing is not your main horn, it is a horn which is a part of the alarm system. When you lock/unlock the car, the alarm runs a diagnostic and if it finds any bad components or "open circuits" it will beep a specified number of times to indicate a problem.

I also have an '02 C4S and upgraded my factory radio. I read a bunch of posts on various forums that stated this would cause an isue with the alarm, however I have not had a problem. I ordered the install kit from a very knowledgeable ebay seller, so it is possible that he fashions the wiring harness to bypass any alarm issues, but I can tell you that I did not make any special modifications when installing the head unit so I am not sure how much truth there is in the posts indicating that it will cause a problem.


Regarding the doors and windows: The windows are designed to drop approximately 1/4 inch whenever you open the doors in order to clear the rubber gasket around the door frame. If your windows are not consistently dropping when you open the door there is a problem, and there are a few posts on this site which discuss the various causes. I had an issue with the passenger side micro-switch which caused that window to intermitently not drop when opening that door was opened. The horn for the alarm would beep when I unlocked the car with the remote or switched off the igniton when a problem was detected.

I am not sure why an issue with the window or one of the window sensors would cause a problem when the car was running, but I would start there if your windows are not working correctly all of the time.

If the radio was the cause I would think the problem would have manifest itself from the time the radio was first replaced.

The battery can be tested at most auto parts stores or the dealership to easily rule it out as a potential issue.



Let us know how the endeavor goes.