The Lotus Grand Tourers

My 85 Excel had fitted before my ownership a Cobra 7928 Alarm system as an after factory installation.
after a major engine refit when trying to start the engine by ignition key and as usual using the Cobra fob to enable the ignition nothing started.
I found a very low voltage at the coil, no sparks and as I needed to move the car I rigged direct battery voltage to the coil and a by.pass cable to start the engine starter.
I now intend to remove the Cobra anti-theft system and ask Forum members if they have any circuit diagrams of a Cobra installation to help identifying the wiring to be removed.
I do have the standard Excel circuit diagrams.

I also add a photograph (JPG1389) of a Cobra thingamee which I have never used and do not know what purpose it has, any offers?.

Many thanks in advance

Dave the cog

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Hi Dave,

I had an aftermarket immobiliser/alarm fitted to my car too, I think the alarm may have been a Cobra but I cannot remember for sure. The immobiliser has long ago lost any label to indicate its origin!

By the time I owned the car, the alarm (located under the bonnet) had been disconnected, although I only discovered that later on as I removed the alarm box/speaker, then gradually removed all the rest of the wiring as I discovered the other ends were not connected to anything.

The immobiliser was separate. This is armed/disarmed by a chip that fits into a slot located near the ignition key - is this the same as yours?

Mine worked fine until about a year ago, when I suffered several occasions of failing-to-start then mysteriously jumping in to life, until one day the jumping-into-life bit didn't happen. With Tony (MetBlue)'s help we diagnosed this as the immobiliser. It simply interrupted the feed that should go to one side of the coil, sent the signal via the immobiliser then back to the coil. Re-connecting the wire directly to the coil as Lotus intended bought the car back to life.

Then, this New Year (following an abortive dash-out attempt to fix a leak that turned out not to be the heater matrix after all!), the immobiliser decided to disable the starter motor. Again, the immobiliser simply interrupted one of the wires deep under the dash, I think it was the signal to the starter relay but can't remember. Again, removing the bypass and connecting the wires as Lotus intended restored life (after several frustrating hours of diagnosis). I recall the immobiliser wiring had been done using Scotchloks .

I think the immobiliser is still inserted into the fuel pump circuit, so a thief may have spark and starter motor to start the car, but they won't get far. I should probably get rid of that too and return it all to standard, but I have too little time and higher priorities right now!

Wiring is not very helpful, as all the wires to the immobiliser unit are black! But essentially for each function affected (coil, starter, fuel pump) there are a pair of wires which break into the wiring that should be there. Probably a live and earth in there too.

Hope this is helpful.

You can get manuals from here
https://manualsguru.com/?ads=true&msclk ... aedb3c3065

I put in Cobra 7928 and it came up with a manual. Cost 0.95 euro's. Can't reccomend them as I have not used them myself but might be worth a go.