I copy/paste my reply from the other forum just to make clear what's going on in this particular case which has nothing to do with the pretensioner's plug under the driver's seat:
"Hi, unfortunately the SRS ECU is not the best when it comes to generate fault codes cos it can hit and miss from time to time but presuming the code is real cos hawkeye is the most reliable with it the probem is somewhere in the harness which connects to the ECU cos there is no other place where the pretensioner's circuit can meet an ignition live.... to double check the code you'll have to disconnect the battery, unplug the ECU and the RH pretensioner and make continuity test in the ECU plug(C0256) cos if the fault is matching the code you'll have to find continuity across pin 15(ignition live/green wire) and one of pins 6(brown) or 7(brown/red) cos these are the pretensioner's circuit. If no continuity the ECU is suspect and must be ruled out by swapping it, we'll speak again according to the result."
CONCENTRATE TO NOT MEASURE IN OTHER PINS
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In addition i cropped and edited the relevant part from the diagram to explain cos for that
B1018 ( short circuit to ignition in RH pretensioner circuit permanent ) fault code there is a short between the green ignition live and one of the pretensioner circuit's wires which can happen only in the part of the harness where those wires are close to each other or withn the ECU, the pretensioner's yellow plug is C0254 which has no live in it and is far beyond the point where those wires can meet
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