[W126 Coupe] SEC...antenna, rear fog lamp, front fog lamps, warning buzzer

[Dick Spellman]

Hello list types:

Antenna:  The trigger voltage and current of 0.1A at 12vdc from the 
aftermarket radio does not appear to be sufficient for triggering the 
original Hirschman antenna using the dash mounted antenna switch.  When 
a source battery is directly connected through the switch, the antenna 
works.  I am going to wire a sensitive trigger relay with 7amp contact 
rating into the circuit so the radio will trigger the relay and the 
relay will pass full battery to the antenna trigger circuit so that it 
works properly.  Anyone else encountered this in their conversions?

Rear fog lamp: In looking at how the rear fog light on the euro sedan 
driver's tail light is wired, I noted that it has an 8 pin connector 
with all 8 pins wired on the electrical harness.  Comparing this with 
the 83 SEC and the 90 US sedan (that do not have the rear fog feature) 
you have the 8 pin connector but only 6 pins on the wiring harness.  The 
bottom 2 pins are absent and the respective wire harness leads are 
missing.  So, I assume from this that a single 'hot' wire must be run 
from the combination dash light switch (terminal NS on my 83 switch), 
plus 2 pins added (1 the NS contact on the combination switch and the 
other to ground in the fender by the antenna top or the ground at the 
next socket over) and the extra bulb socket and wire with bulb added.  
Seems a bit much work to enable this option.  Has anyone done it?  To 
clarify terminal NS on the combination switch provides 12VDC only when 
the switch is in headlamp mode (an 83 requirement) and pulled out two 
detentes.  I've not been able to identify the open terminals on the 
combination headlamp switch that would complete a circuit and illuminate 
the center dot on the headlamp switch itself.

Front fog lamps:  The 83 fog lamps only light when the main headlamps 
are selected first.  In other words unlike later model MB's where the 
parking lights are selected and then you can pull for the fog lamps 
absent the headlamps, the 83 does not permit this.  So, I've identified 
the two fog lamp bulb positive feeds in the combination switch and 
removed them from the switch.  I am plumbing them into a 10 amp rated 
12vdc relay and then taking the trigger for this heavy duty relay from 
the dash rear cabin courtesy lamp switch (rear lamp circuit now 
disconnected) that I never use.  I've removed the wire from the 
combination switch (NSE (always hot 12vdc) and shown as fog lamp power 
source only)so it will be as the factory wired it with the only 
difference being that the source now feeds the circuit through this new 
relay vs. the original combination switch.  I may wire a small LED and 
piezo(under dash) into the headlamp switch bezel to remind me to shut 
the fogs off when exiting the car using the door switch circuit to 
complete the ground on the piezo.

Warning buzzer: I hope to eliminate the ugly warning buzzer with a 
two-tone selectable piezo like the euro has.  It sounds more like a 
whistle (not at all irritating) and has two different tones.  One for 
door open key in ignition and the other for the combination switch on in 
one state or another.

Hope everyone has a Happy 4th.  I've got a few days to tinker with the 
SEC so, that's what I'll do in between gatherings and fireworks in Boston.

Take care,
Dick working on the finer details of an 83 380SEC that will soon be a 500