Which fails first ... the distributor or the immobiliser ???
There has been much discussion on various web sites concerning Ford Probe distributors and the UK Bosch immobiliser. Some people blame distributor failure for damaging the immobiliser, some blame a faulty immobiliser for damaging the distributor.  So who is right ?
 
Here is MY interpretation of the evidence available...
 
Firstly a few FACTS need to be established...
 
  1. US Probe distributors fail regularly (you only need to frequent the Ford Probe FAQ or ProbeTalk for evidence of this)
  2. UK Probe disributors fail regularly too.
  3. US Probes are not fiited with the Bosch immobiliser (or any immobiliser) as standard as far as I know.
  4. Some UK Probes are fitted with the Bosch immobiliser referred to on this website.
From the facts presented above it can be deduced that initial distributor failure is NOT connected to the immobiliser (but see later)... because the US probes which are not fitted with an immobiliser still exhibit distributor failure.

Typical course of events:
 
  1. Progressive distributor failure causes excessive current in the immobiliser, causing damage to the solder joints.
  2. Distributor fails completely and is replaced. Immobiliser typically receives no attention and remains faulty.
  3. Faulty immobiliser causes cut-outs similar to distributor failure.
  4. Distributor is diagnosed as faulty and replaced again.
  5. Cut outs caused by faulty immobiliser MAY then cause premature ignitor failure (although this has still to be proved).
  6. Immobiliser now blamed for distributor failure.
In my opinion, the distributor is the guilty party, (the distributor fails in US models where no immobiliser is fitted). The distributor damages the immobiliser fitted in UK Probes. The immobiliser is neither badly designed nor constructed...it is damaged because another component has failed (in this case the ignitor) and exceeded the operating specifications of the immobiliser circuitry. Once damaged by the initial failure of the distributor, the immobiliser typically receives no attention by FORD when they replace the distributor. The immobiliser now causes cut-outs of its own, and MAY be to blame for subsequent short ignitor life, although there is no proof of this.

IN SHORT... in the first instance the distributor components damage the immobiliser, not the other way round.
 

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