How do I disengage the engine immobiliser on my 300SL R129

Start by ensuring any immobiliser is disengaging.

To start, an engine needs a decent cranking speed, compression, timing, the right amount of fuel and a quality spark.

Discovering why an engine doesn't start means working through that list of requirements until the fault is discovered. Checking the ignition components and spark is usually the easiest to begin with.

It is worth knowing too much fuel can also prevent an engine starting...

make sure when ignition is turned on or when cranking engine that immobiliser is disengaging.also locate crank angle sensor usually mounted in bellhousing to read off flywheel or at crankshaft damper pulling.inspect and clean magnetic side of sensor and connection terminals also possible damage to cable

black box,under dash,factory or aftermarket immobiliser?

make sure that a signal is generated from the crank position sensor when cranking the engine if not sensor is faulty . Otherwise check for spark at plug leads check for fuel pressure at the rail and make sure immobiliser is disengaging

Duplicate question.

Cheers guys but it's not a key fob, it's a weird torpedo shaped device you press directly onto a small metal disc beneath the immobiliser light. It's an old L reg Saab 9000. Any ideas?

r129 seat removal/disassembly :http://www.youtube.com/watch?v=UnT0pQHil6I
Thank-you tamango!

I would take off the alarm and see if the problem goes away. If it does you know the problem is with the alarm. I am in the alarm business and will not have one on any of my vehicles unless they come that way from the factory.

dealer only to re programme key into car it can only be done with vehicle, not away from it .Sorry for no easy fix unless you want to disengage the factory immobiliser,which if its a diesel is a fairly simple procedure but not for a petrol engine

unlock either driver door or boot with the key this will dissengage the immobilizer