Darn it. Immobilized. Help!

[Atle]

Was fitting a nice new LED alarm warning light from Holden Classics when the positive and negative wire touched each other and sparked.

After the new light was in place in the centre console, I pushed the FOB button to test again but nothing happened. I tried to start, starter motor turned but engine did not fire and all lamps on the dash are dead.

I have been immobilized. I have a 1991 SE with a Cobra 7915 alarm with door-lock.

I have spent the last 3 hours trying to figure things out. I must have blown a fuse. All fuses I can see are intact, and the instruction book has no alarm fuse indicated. I have called the Lotus dealer & garage where I got the car but they had no concrete advice as the system is apparently after-market. I had tested the new bulb and alarm function before I started mounting it, before I sparked the wires, and it worked fine. I have tried re-setting by pushing both FOB buttons, and otherwise scanned the forum for advice.

I have to push the car back in its garage...anyone please help! Where is the fuse? What shall I do?

Edited March 20, 2008 by Atle

[davegtst]

You will probaly find there is an alarm fuse near to the alarm module. As it is an aftermarket alarm the module will be hidden somewhere but they are usually easy to find under the dash. Don't bother taking it to Lotus if you can't get any joy an alarm speciallist will probably have a better idea what to do and would probably be alot cheaper.

[Atle]

Thanks Dave, I have almost broken my back trying to find a module or fuse under the dash, the siren is under the bonnet with a fat wire bundle coming out of it, disappearing through the firewall and dispersing in a sixty different directions under the binnacle.

Now that I think about it, there is a mysterious box squeezed between the steering column and the lower dash, screwed from below right next to the fuel hatch opener switch. About the size of a Matchbox car toy box. I can see a green printed circuit sheet inside it, there is no bottom cover. Will check tomorrow, just rolled the car back into the garage time to take care of my neglected kids this afternoon....

[Atle]

Still immobilized, called the Cobra hot-line in Germany and was given the following advice:

The control unit and siren is one and the same box, integrated system under the bonnet. I can override the immobilizer by opening this box and bridging two identified wires - fine but by opening the box the watertight integrity thus entire alarm system is permanently destroyed, which means new alarm system must be installed. Blah, $$$$$.

The next option is checking the fuse, hopefully the problem is limited to a broken fuse. I have downloaded the wiring diagram, which shows that the system's power is either drawn from the fuse box from some shared circuit, or the power is drawn directly from the battery on a remote fuse. The LED light (that I short-circuited) is directly connected to the main power supply wire thus directly in connection with the fuse. I can not imagine other than that short-circuiting the LED wires will blow a fuse?

I have checked all the fuses in the fuse box, all are intact. I have not found any remote fuse yet.

Does anybody with a 88 - 93 Esprit with a Cobra 7915 alarm system know how the system is powered, fuse-protected and where the #x**@%& is this fuse???

Any help appreciated!

[martynv]

Hi Atle,

It's likely they've cut in to the ignition circuit under the ignition relay on the passenger side bulkhead it's hiding under a black plastic cover the one with the spring clip on it that holds the jack handle in place. Have a look and see if any non-original wires have been joined to cut wires under the relay, if you can re-make the original wires this may atleast get the car running again pending a full repair. Unfortunately it is possible that they've also cut the fuel pump wires as well, but you'll know this once you've got the ignition back on again.

One other thought is to try disconnecting the battery and reconnecting in the hope of reseting the alarm system if it was somehow spiked by the short circuit.

Martyn.

[fjmuurling]

I agree with Martyn, the alarm is probably connected to the ignition relay. Mine was anyway, I found out when I removed the old alarm system (not a Cobra) as I'm in the process of fitting a new system.

Freek

[Atle]

Thanks guys,

I have tried the disconnect battery thing, local car dealer advised some alarms reset by disconnecting the negative from the battery for 60 seconds. Did not work for me. Tricky one this.

Had a sudden spell of snowstorm this afternoon - staying indoors so we will go out tomorrow and check out your info. My next door neighbor Haraldur (coincidently the man behind the "Arctic Trucks" on Clarkson's polar spree - sorry name dropping) has just offered his help too.

[martynv]

Was fitting a nice new LED alarm warning light from Holden Classics when the positive and negative wire touched each other and sparked.

Hi Again,

I was just thinking about the LED bit, most LED's have a series resistor somewhere in the circuit to limit the current to some where in the region of 10 - 50 milliamps depending on the LED. However since you have said there was a spark when the two wires touched this can't be the case with your one since little or nothing would have happened when the wires touched other than the resistor getting a bit warmer than usual.... This leads me to believe that your original LED was one with a built in resistor or a semiconductor circuit that maybe made it flash for instance. My question is now does your new LED have an in-built resistor or not ? if it hasn't and it is as you say across the 12v supply somewhere it's quite literaly going to get fried. You can work out the resistor is required by:

(12volts - 1.2volts) / required current

1.2volts is a rough guess of the volt drop across the LED. So for instance if you want say 10ma you need:

(12-1.2)/0.01 = 1080 ohms (so a 1K resistor would be fine)

Martyn

[Atle]

Good point there, I was thinking maybe the different LED light is screwing up everything. Both the new one and the original one connect directly to 12 volts, with built-in resistor. I tested the new one before soldering it and it worked. It was in the process of fiddling with the soldering iron the positive and negative leads touched and sparked. I swore but just carried on the soldering and fitting.

This is indeed very embarrassing, I am ashamed. I have been fooling around with cars for 30 years, always disconnecting the battery before working on any electrical system. Again complacency kicks in - this was just such an insignificant mod.....duh...

I will thus try to replace the original LED however (it has a much smaller bulb). Winter came back this morning, ice cold wind and snow. So no work on the car can be carried out.

Waiting for warmer weather...

Edited March 21, 2008 by Atle

[Atle]

Problem solved!

Thanks to next door neighbour wizard Haraldur.

It was as we thought, the remote 15A fuse between the battery and the alarm system that had blown. Simple enough but the fuse was hard to find...

Replaced the fuse, reset the alarm (press both fob buttons for 20 seconds) and now everything works. Car starts and new LED blinks.

Happy Easter all!

[espritpassion]

Hello Atle....I seen you old post....where is located this FUSE ??....I think to have the same problem on my GT3....Im chatting in the Engine tech.room