Lotus / Cobra Alarm Service

Lotus Cobra Alarm

Lotus Alarm Posts

Lotus have used Cobra alarms for over a decade now. The alarm was a factory option which later came as standard on certain models.

Normally the whole Lotus alarm stuff slips under the radar (not surprising being in NZ!), however, I was recently asked by a customer if the siren on his Elise could be replaced.

To quote Steve (Lotus Elise Series 1 111s 1999 owner)

Perhaps the main reason i was aware that there was a problem is because the main battery wasn’t holding a charge.  Its a hobby car but should have been ok for a couple of weeks at a time without the battery running so flat it wouldn’t start.  I started looking at the owners forums for a solution.
Owners of other vehicles in daily use may have the same problem ( dead batteries and a silent alarm) but not be aware of it but their alternators are probably working hard.  The forums i read suggested a lot of Subarus where fitted with the same alarm units.
I guess it comes under alarm health – we all have bad days when we trigger alarms accidentally perhaps if your customers like me can’t remember the last time they had such a day then they should test their alarms out.
Lotus Cobra alarm service

Lotus Elise with a Cobra Alarm

I agreed to take a look but had no idea what to expect. Cobra NZ has no information on the Lotus Elise system and Cobra international would not divulge the information I required.

I advised Steve that I would bring along two possible replacement sirens with the hope that the Cobra in his Elise shared a siren with other Cobra systems. But no promises!

Of course, the siren was different! I opened it up and the battery was showing early signs of corrosion. Steve said he had read about badly corroded batteries leaking acid which had eaten the circuit board!

Lotus flat battery?

Cobra alarm battery pack

I ended up raiding a battery pack from another cobra siren. Although a different shape and sporting a different plug was still the same voltage. I modified it to fit inside the Lotus siren.

Battery Drain Solved

Good result, the alarm now works and the Elise is starting every time. So Steve’s suspicion that the siren was causing a battery drain was spot on. You have to love decent car forums…

It is worth noting that the remote for the Elise is the Cobra 4T7777 which is still available, but like all other Thatcham systems, the Over-ride pin number is required to access program mode.


This entry was posted in Car Security, Cobra, Lotus, Trouble Shooting!. Bookmark the permalink.

1 Response to Lotus / Cobra Alarm Service

  1. Avatar Julian says:

    Replacement remote case for the AT7777 remote is now available:


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.