Author Topic: Fake Alarm LED  (Read 4474 times)

guest1272

  • Guest
Fake Alarm LED
« on: March 03, 2012, 06:22:01 PM »
Another quick'n'easy mod here.

Noticed how your Jazz "acts" like it's alarmed (e.g. flashing the indicators on lock/unlock) but actually isn't? Well, I thought just to put a finishing touch in, I'd add a cheap fake flashing LED.
These come for a couple of quid off ebay all prewired and simply require connecting to the correct wires.

It works by connecting the positive lead to permanent (battery) positive, and connecting the negative lead to Accessory (Ignition) positive. This way, when the car is off, ACC+ is not live but PERM+ is so current flows and the LED flashes. When you sit in the car and switch on, ACC+ now becomes live but so is PERM+ so no current flows so the LED turns off.

The problem arises in that some circuits will now "go live" when you turn the ignition off as they're receiving a positive via the LED you've attached into their circuit (so when I tried connecting it to ACC+ fuse, the radio turned on....same as when I used Cigarette Lighter fuse). Alternatively, other circuits may confuse the ECU and result in Power Steering to switch off (e.g. using the rear wiper motor fuse).

So I ended up using an existing fuse for PERM+ (one that was already live on the multimeter whether ignition was on or not, the wire on the right), but for ACC+ I bought a spare 7.5A fuse and added it into a circuit that wasn't there ----- my Jazz doesn't have daytime running lights, so I simply "used" that unused circuit that has ACC+ power but isn't wired up to anything (the wire on the left of this picture):


The way I did it was to "curl" the bare wire end around the right hand blade of the micro fuse. This way, the LED is actually protected by that fuse (it's on the right side of the blade), but more importantly, it is very secure (fuse blade fits very tightly when there's a wire along it) and I haven't cut into anything and risked ruining wiring looms. Plus, if I want to remove it at some point in the future, I simply get a blanking plate from ebay for a couple of quid, and take the wire out from the fuses (remove fuse, unwrap wire, replace fuse)....so it is easily reversible and hasn't caused permanent changes to the electrics.

Wired into blanking plate:


The blanking plate is the only thing unused in my Jazz (I think it's where the comfort lighting switch would otherwise sit) so wiring it in here meant that it was a) near the fuse box and b) looks fairly "stock" (plus, as mentioned above, it's easy to reverse by putting a new blanking plate in).

Clear LED in discrete housing with ignition on.



When Flashing (ignition off):



It's nice and bright, but the only problem I have with it is that it flashes at about 2Hz, and I would've preferred something more along the lines of 1Hz, but it'll do for the time being :).

guest907

  • Topic Starter
  • Guest
Re: Fake Alarm LED
« Reply #1 on: April 08, 2012, 10:04:05 PM »
My Jazz has a flashing red light on the radio unit when locked.

I have fitted the fake LED in other cars but used the battery operated ones off ebay...no car wiring to be messing about with, battery lasts at least 2/3 years and just as bright as 12V version.

guest1272

  • Topic Starter
  • Guest
Re: Fake Alarm LED
« Reply #2 on: April 09, 2012, 03:53:28 PM »
My Jazz has a flashing red light on the radio unit when locked...
My jazz has the same light - unfortunately it looks nothing like an alarm light, instead it looks like what it is (a 'my radio alone has a code that means there's no point trying to nick me' light). It also has nothing to do with the car locks as it turns on when ignition is off and so is the radio. What I specifically wanted was a light that looked and acted like a 'car alarm led'.

I also considered the battery cell powered alternatives but deliberately chose this method instead because it offers a number of advantages:
• same cost if not cheaper (fewer components)
• never requiring replacing anything ever - its all automated and won't require buying replacement batts
• if wired as I have done its entirely safe, quick and easy to install with no interference of existing systems
• no danger of batteries leaking because it doesn't run off a separate battery
• no separate switch needed which you have to remember to turn on and off - this runs on the ignition so is essentially 'fire and forget'

...but yes, apart from that, the battery operated ones are an alternative ;)


Tags:
 

anything
Back to top