Airbag warning Light comes on intermittently Astra H sRi 3dr 1.9

[squig60]

Hi all,
My first post. This is a problem on my daughters Astra H SRi 1.9 2008 model. Her airbag warning light comes on intermittently. I have had problemswith the ca. A bit of history. About a month ago the airbag light started coming on and off, plus the car would go into "crash" mode. The car was never in a crash. I found out from Opel/Vauxhall that it had the cim clip installed in 2010. The main dealer said that computer was saying the fault was with the airbag ECU. I wasn't happy ECU was going to cost 450 euro.
I took the car home and myself and brother in law took off the cim module and moved the clip slightly on the cim. Lo and behold airbag light went off.
Now the real bad news !!!!!!
A few days after this my daughter was heading out on a 200 mile trip. The gearbox went kaput and it split the bell housing (173,000 kilometers) I got the gearbox rebuilt new flywheel and all the rest of the kit that was needed. When my brother in law put it all back together i was left with two warning lights on the dash, steering angle sensor ( the light that looks like the car is in a skid) and airbag warning light. We figured the cim was faulty (maybe it is maybe it is't) Anyway garage replaced the cim and reprogrammed anything that needed reprogramming. All lights went out on the dash when the car was driven. However, after 10 or 15 minutes the airbag warning light came back on. The mechanic put the car back on the computer and when he went to the airbag section it said "no communication" It was near finishing time in the garage so no more work was done on it. the mechanic reckons it could be the airbag ECU and that a 2nd hand unit can be used if it from the same model. I need your advice on this.
I think it is a wiring fault in the seat as the light comes on and off so randomly. Where do I start to trace a wiring fault? Is there a good youtube video on removing the seat and cover or where to look for chaffed wires.

many thanks for listening to my rants. All advice welcome

Squig

[liviu2004]

Any fault in the wiring will make the airbag light stay always ON. Regardless if the circuit becomes healthy by itself.

[squig60]

I noticed something else today. If i use the central locking button on the dash the car goes into crash mode

[domtorredo]

Without fault code not easy to start 6 airbags couple of crash sensors and all wiring
To get seat out 2xt30 bolts at back of seat
Would recomend getting fault codes before striping down anything just to find start point