Thanks for your prompt reply.In the past I had problems of corrosion on the GEM module plugs which I cleaned and was fine.So what might happen if I did the same to these modules ?

If there’s no issues with the engine and abs systems, why do you need to clean the terminals ?

I do have a problem with the ESP part of the ABS,When turning sharp right the ESP operates on the front nearside wheel,the ESP light flickers slightly,and the ABS light doesn't light at all.Forscan pointed at the ABS sensor,which I replaced but did not cure fault.Then replaced YAW sensor,no difference.Internet searches suggest water ingress to ABS module and ECM.DTC are C1280,C1155,U2023 So thats my predicament at the moment,Thanks.

Yes,monitoring the live wheel speeds using Forscan shows them all to be the same,with a slight variation when turning as you would expect.I looked at the ring magnet on the bearing and it seems fine.If I turn the ESP off,the problem disappears,so I'm a bit unsure what to try next !!

Does the car steer straight with the steering wheel pointing straight ahead ? What is the steering angle offset when driving straight ahead?

Sorry for delay,yes the car drives straight,I had all 4 tyures replaced last December and 4 wheel alignment.The steering angle I'm not sure about but again using Forscan the oscilloscope shows the correct measurements when turning steering wheel.So I'm stuck !!