[Tatsfield]

Many cars suffer fault warnings on pyrotechnic devices like tensioners because the same wiring is used to test the circuit as is used to fire it. The difference is that the test voltages are very small and the current will not operated the igniter. If there is a corrosion problem on a connector in the circuit and by that I mean a very slight rise in the impedance, the ECU will not recognise the returned test current as a pass and fail the system. The same connector would probably pass the very high voltage needed to fir the device so in actuality it is operational despite the warnings. However the car would never pas an MoT with the warnings and you wouldn't wan t to gamble with the possible fault, so it's worth checking all the connectors in the circuit.

On a previous car I found that the tensioner firing cables ran at the lowest point under the seats and were prone to damp just from wet shoes on the carpets when it rained. The only reason there are connectors in the circuit is for the assembly on the line or for the removal of the seat so I cut out the connectors and soldered the joints and never had another problem. I never needed to remove the seat but if I did, I'd have known that the soldered joints would have to be broken.