borland

I was looking at this mobile electronics web site called the12volt.com

http://www.the12volt.com/

They have some great relay ideas for making circuit modifications.

Here's one to keep the radio on until you open the door.



Here's one to make the Side Markers blink with the turn signals (daylight only).



Most aftermarket keyless entry systems send a lock pulse of 1 second. On the later 928's (1990-1995 S4/GT/GTS), ideally you would want no more than 1/2 second pulse because the window controller will try to close the driver's window after the first 1/2 second of the 1 second pulse. Here's a way to reduce the pulse width to 1/2 second.

Alan

That is a useful site... lots you can do wih relays...

I have an alternate version of the first function installed on my car - a single relay version that also maintains the off during starting feature... It is a nice feature (my Ford Expedition has it so I figured the Porsche should too).

The middle one doesn't seem to be designed for (/able to do) what you suggest - I think its intended for the "around corner" constant illumination type lighting often seen on detroit's big old boats...

However it is possible to make the side markers also act as indicators - either just by wiring them differently (sometimes called "trailer style" wiring - e.g. ground them using the turn signal feeder.

OR:

For a more universal method (will work with LED bulbs) you can build a 2 transistor 2 resistor circuit to do the same thing. I have a pair built that I haven't installed yet (awaiting the next trip into the fenders)

Function:

Front/Side Marker Turn Signal Marker Lights
==============================
Not Illuminated....... OFF ........... OFF
Illuminated ............ ON ............ OFF
Illuminated ............ OFF ........... ON
Not Illuminated....... ON ............. ON

So basically when the markers are off the front/side markers flash with the turn signals, when the marker lights are on the front/side markers flash opposite to the turn signals

Whilst you can use a relay as you note to shorten door lock pulses - the 928 power module requires low signal power - so you could just use a similar RC network directly without the relay. Relays are useful for power applications but add a new reliability point - so worth avoiding whenever possible.

Alan

borland

Alan,

On shorting the pulse width.....

I thought about that. Would you also add a diode between the central lock's 'Lock' line and the RC network? There are some web sites that calculate the capacitor charge decay times...

http://hyperphysics.phy-astr.gsu.edu...capdis.html#c2

Of course, defeating the later model Windows-Up-with-Key feature only requires disconnecting one wire at the window/sunroof controller. It's a feature that's not that useful to me.

Alan

Yes - best to use a diode so it doesn't have any effect on the oher lock inputs... I'd also use a much smaller capacitor and larger resistor - same TC but less current for the KE to drive.

Alan

borland

Thanks,

After considering where to place a diode, I determined there is no need to shorten the KE lock pulse to under 1/2 second. So the RC network is unnecessary. This is only for 1990 S4/GT.

What's needed is to add a single diode at the central locking controller. The required wiring mods are:
- At the central locking controller, install a diode between the door security key switches 'close' wire and the pin 7 'lock' wire.
- At pin 8 of the Additional Control Unit Alarm System controller, cut the wire from the window controller (pin 6), and reroute this wire to the security key switches 'close' wire.

This mod allows the KE lock the doors and activate the factory alarm without the window controller sensing this action. When the security key is used to lock the door, the sunroof-close-window-up-with-key feature is still functional.