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Sold my Exige S
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Discussion Starter · #1 · (Edited)
Here's a condensed walkthrough for this job in one single thread. Much of this info is scattered over tons of threads going back to 2005, but some of those threads have plain bad info including people who believe the immobilzer is the alarm. SirLotus has provided the brunt of this knowledge and he deserves most of the credit.

Why disable the Cobra security system? In recent months, either my Cobra alarm module or both FOBs became flaky. The FOB batteries were good (3.2V on the multimeter), but I was having to resync the FOBs every few weeks which meant something in the Cobra system was failing. Recent resyncs took multiple attempts for success and I worried this could worsen and leave me stranded.

So if you don't mind locking your doors with the key and no longer want to be a slave to Cobra security and PIN gremlins, do this modification sooner than later!

Background: The Cobra security system for 05-07 Eliges consists primarily of a microwave sensor, immobilizer, alarm module, and alarm siren. Your FOB transmits directly to the receiver inside the alarm module, which then flows downstream to the immobilizer, door locks, etc,. Later year Eliges used PFK security systems presumably due to horrible feedback about the Cobras.

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14 Steps. Photos are at the bottom (I can't attach them inline for some reason).

1. Disconnect the battery's negative terminal.

2. Remove passenger seat. Push the driver's seat forward and then remove the rear bulkhead cover. If you have a harness bar,
this must be removed before the bulkhead can come out.

3. Locate the immobilizer (on the rear panel behind the driver's seat) and disconnect its white harness. Remove and discard the immobilizer after separating it from the rear panel. The immobilizer harness does NOT need to be reconnected for this mod.

4. On the car's side of the white harness, cut off both pairs of end wires.

5. Strip the four end wires that you cut and splice the respective pairs together by any secure means. This now enables the circuits to the fuel pump and starter.

6. Unplug the microwave sensor and remove it from the rear panel.

Now the complicated job - unplugging the alarm module. This is located behind the passenger side cubby hole which has a razor sharp aluminum edge. Note: If you don't unplug the alarm module, the telltale light on the gauge cluster will flash even while driving because it can't talk to the immobilizer.

7. Remove the two plastic trim covers of the cubby hole (two phillips screws for each cover).

8. Apply duct tape to the aluminum trim at the bottom of the hole so you don't cut yourself. Initially, I skipped this and still sliced my thumb with very little effort. TAPE THE EDGE OFF!

9. Locate the alarm module. It will be buried behind foam, about 4 inches in and to the right in the compartment. It's wrapped in a plastic bag for moisture protection. Cut the black zip tie securing the plastic to the wiring feed, and remove the plastic bag.

10. Disconnect the white harness attached inside the alarm module. There are two black plastic tabs pointing up on each end of the harness. Push these tabs out to the sides and pull up on the harness to separate it. This took me many tries. The module slides into a bracket which is screwed down, so you can't wiggle it closer unless you break the bracket's tabs.

11. Decide if you want the alarm module removed or not. The module's base is secured to the aluminum panel with two phillips screws that are very difficult to access (removing the dash won't help). After prying the module's cover off, I used a long ratchet with a phillips fitting to unscrew the mount, but it wasn't easy. Else, just leave the alarm module intact but unplugged.

12. Optional: Locate the alarm siren bolted to the front crash structure on the driver's side. Unplug and remove.

13. Refit the cubby hole trim covers, rear bulkhead panel, passenger seat, and reconnect the battery.

14. Discard your Cobra FOBs. You're now Cobra free and have reliable starting every time!
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Note: SirLotus and others have stated that you will lose your central door locking if you do these mods. However, my CDL still works even though I never need it. My interior lamp is also operating even though some stated they lost this when the alarm module was unplugged.
 

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ive been contemplating doing this for years now but never felt comfortable with all the threads having different info... thanks for consolidating this down


how was getting that passenger seat out & back in with that rear side bolt? (i hear its a pain to access as well)
 

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Sold my Exige S
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Discussion Starter · #3 · (Edited)
how was getting that passenger seat out & back in with that rear side bolt? (i hear its a pain to access as well)
If you mean the rear bottom bolt nearest the door, I daisy chained socket extensions together to get enough clearance. The side bolt securing the passenger belt is removed after you pull the seat out of the car, extending the seat belt with it to allow enough working space. Sadly, that job isn't too bad compared to some of the tasks above!
 

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I'm sure my future self will want to thank you for this :)
 

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Best alarm thread ever. Wish I found this earlier. Been struggling and searching all over lotustalk.com for info which turned out to be confusing and conflicting at times.

I just unplugged the alarm module behind the dashboard panel cover (my immobilizer was already disabled when I got it but had the annoying red blinking light when driving). Thought I'd chime in and add to this valuable thread.

1. It's dark in there. Having light in there makes a huge difference. I shoved a headlamp into the space and to the left towards the steering wheel so the light was shining into the alarm module.

2. I could not find the module at first (I had not found this thread and pics yet) . I had a huge, thick piece of foam blocking everything. It took a fair bit of effort and wrestling to move it all off to the side. Then I saw it.

3. I found a strip of foam glued down to the main sharp bar that others cut themselves on so it wasn't sharp. There are sharp corners on both sides though which I taped off tho.

4. I started wrestling with the black tabs on the corners of the alarm module before I re-read that I should only be unplugging the white part. Then looking more closely I saw the white inside the module on the top and the two tabs I was supposed to push open instead.

5. To get it out, I inserted a long flathead screwdriver into the mess of wires coming up and out of the plug, spread the two tabs with my hand (can only barely fit a hand in there). Then leveraged the screwdriver up against the wires to get it to unplug and come up/out. I couldn't spread the tabs AND pull up on the wires with just one hand. Took me just one try using that long screwdriver.

6. I lost my interior light. My CDL still works. Well, works the same as it did before which is not correctly. Drivers side door only unlocks (regardless of which direction i press the CDL button at the gear shift lever). Right passenger lock remains dead.

Hope these tidbits help.

P.S I ripped the plastic bag off of the module and did not put a new one or a cover of sorts on fyi. I assume this is fine.



Sent from my SM-G955U using Tapatalk
 

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I just did this job, so I figured I'd add my notes as well.

First, I didn't remove the driver's seat, just pushed it up as the OP suggested. In doing this, access to the immobilizer is very limited. So instead of modifying the car side of the immobilizer harness, I modified the immobilizer side. I literally cut all the wires a few inches up, removed all of them from the harness except the ones on the end that are needed, crimped them together, and plugged it back in. Easy cheese, and easy access.



Onto removing the alarm module. Everything around this module was SHARP on my car, so I taped it all off, and didn't get a scratch.



This is what the module looks like with the harness attached. The white part of the harness is literally hidden 100% by the module itself.



And this is what it looks like after it's unhooked. Those circles are around the two tabs that you need to push outwards to get the harness out. At first I was having a difficult time because I thought I had to push them aside and pull up at the same time, but this isn't so. Just push one to the outside, jiggle the harness up a bit, push the other one to the outside, jiggle some more. Just keep doing that. Literally took me 30 seconds. Also, mine had NO foam at all, just a bag which I pulled off. There is a ziptie holding the two harnesses together, so be careful when cutting that.

 

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2008 Exige S240
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Which part of the alarm system draws the most power from the battery?
I frequently have to use a battery tender even after a few days to get the car
started. It really deflates things when you want to go for a drive and you
hear a click, click, clickkkkk sound....followed by a ****, **** motherF'er
-Robert
 

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Which part of the alarm system draws the most power from the battery?
I frequently have to use a battery tender even after a few days to get the car
started. It really deflates things when you want to go for a drive and you
hear a click, click, clickkkkk sound....followed by a ****, **** motherF'er
-Robert
As I understand it, it's the immobilizer unit.
 

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Well today I did the Cobra removal deed on my Elise. Many thanks to those that provided the know how to make it reletively easy. The car side of the immobilizer harness was quite short so my solution was to cut the two pairs of end leads on the immobilizer side and solder them together. That way if anyone wants to return it to stock, no problem. ( I number tagged each pair for the next guy.) The immobilizer harness was then plugged back into the car harness. My interior light still works and the CLS still doesn't work, but it didn't work before the change.
 

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Seems like all I did when removing that evil thing a decade ago did not involve cutting anything. Just unplugged and discarded the thing, put two pieces of heavy copper wire in as jumpers and drove off in joy.


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I have successfully disabled/removed the Lotus Cobra Alarm and Engine Immobilizer.! I just use the key only.

After reading many posts all over the web about removing the Lotus Alarm and Engine Immobilizer, here are my steps. I find that many instructions suggested were unnecessary or confusing. I want to add back to the community by giving my instructions.

How to remove the Lotus Cobra Alarm and Engine Immobilizer.

1) Unplug and disconnect the immobilizer. Jump the pins as stated here. You NO longer need the Engine Immobilizer connected nor it at all.

2) Unplug and disconnect the Microwave Sensor. You NO longer need the Microwave Sensor at all.

3) Remove fuse #11. Noted that the interior light won't work. However it can be hacked, but I didn't bother.

4) Put everything back and you are DONE!
 
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Less is Better
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If you loose the use of keyless entry, universal replacement modules can be purchased from amazon for less than $20. You can reuse the wiring and actuator hardware that's already in the car. You may just need a couple relays. I've installed these on several older cars.
 

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If you loose the use of keyless entry, universal replacement modules can be purchased from amazon for less than $20. You can reuse the wiring and actuator hardware that's already in the car. You may just need a couple relays. I've installed these on several older cars.
I am about to do the above procedure but would like to explore your option of preserving the keyless entry. Can you provide more info on the universal replacement modules, possibly a link or two? Also, would the extra relays be required with the universal module? A complete write up would be great!
 

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Less is Better
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I am about to do the above procedure but would like to explore your option of preserving the keyless entry. Can you provide more info on the universal replacement modules, possibly a link or two? Also, would the extra relays be required with the universal module? A complete write up would be great!
There are alot of modules on Amazon.

Here's one of them.

They will come with instructions on how to wire them up the your system. Different actuators have different power input requirements so it really depends on that. I haven't done the Lotus doors. You might have to do some experimentation to see what the actuators need.
 

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Today I removed the immobilizer and the Cobra Alarm. Blinking light on the cluster be gone!!! Relatively easy operation to disconnect the Alarm module following the above directions. I wrapped the plug in some sheet packing material, tie wrapped it to hold it together, and put it back in the hole. I did not want to introduce any additional rattles or vibrations above what I already have.

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The interesting part of the project was when I got to the immobilizer. I realized that the pins in the immobilizer connector are the same pins I use to make my LED tail light kits. I made up 2 pigtails using the pins and shrink wrap to insulate the exposed portions, and tie wrapped them together and down into the connector so nothing can slip out. I again wrapped the plug in some sheet packing material, tie wrapped it to hold it together. I did not want to introduce any additional rattles or vibrations back behind the seat either.

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The following photos show the jumpers in fabrication and final assembly. I can make these up if anyone is interested.

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Sensitive content, not recommended for those under 18 Show Content
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Almost forgot to mention that my interior light is still working. Others stated that it stopped working when they did this mod. :cool:
 
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