P38 SRS Fault, can any one help?

Since I purchased the car the SRS light has been lit (accompanied by fault message Airbag Fault). I have taken it to local dealer for diagnostics, Testbook reports that airbag ECU has “internal fault no ignition voltage”. Has any one come across this before? I suspect that this either means I have a wireing problem feeding the ECU or that the ecu is actually faulty. Has any one come across this fault before? If the ECU is faulty how much can I expect to pay for repare/replacement, and as for the wiring what are the best things to look out for? ( I was expecting or should I say hoping that the fault would be on the rotary coupler. boo hoo)

Thanks in advance if any one can help
Neil

There are 2 things you can do,first disconnect the battery for 10 mins then carefully do continuity checks on all the Srs cables from the ecu end to where the feeds/earths come from.Second is to disconnect and reconnect the main ecu plug about 10 times - this "scratches" the connections in the plug and may make good a poor connection.Dont be tempted to do anything else in terms of cleaning the connections as they are very delicate/fussy.95% of the time when you connect it all back up again the SRS will self test and the light will go out again - the fault will remain logged in the ecu but this can be cleared at a later date.If the light goes out the system is functional.Good luck !

Think you need to try another Ecu - if you can find a willing donor,the Rave pages may not seem much help but they are usually very accurate.The SRS loom is deliberately designed with as few connections as possible - for obvious reasons.It is only meant to work once,in milliseconds.Sorry,but have not needed to buy any LP SRS Ecu's - the last one that I looked at that testbook told me had crashed,the customer wanted the bulbs in the instrument pack left out.He was selling the car,during the whole time he owned the car it was not functional.(The front diff had punched a hole in the sump where it had had a hard frontal impact)