I took my Zafira for MOT before Christmas and it failed on a few things. It hasn't really been driven since, only moved about our address a couple of times and tinkered with. I sorted the fail list but didn't take it back for another MOT until last Saturday. Unfortunately it's failed again, this time because when the fog lights and left indicator/hazards are both on, the rear fog light flashes (there's only one on the right). The right indicator doesn't set it off, nor can I find any other interferences.

I've read up and everyone says "bad earth". So I've cleaned connections, looked for corrosion, inspected wires and checked continuity on earths to rear clusters. No issues detected but still the fault persists!... My local mechanic said "sounds like a bad earth, bring it in now and we should be able to sort it". So I did but he quickly decided that it wasn't a bad earth. Checked fuses and replaced one bad 15a, but didn't help. Ran full diagnostics, found various old electrical faults recorded which seemed unrelated so cleared the lot. Retried - still got the same interference. So now he's a bit stumped too.

One electrical fault did return after clearing, but it relates to the front dipped headlights. This is a fault I am aware of from first MOT - the right bulb doesn't light. The rubber seal was missing and the wire and terminals were corroded. I stripped them back and put some new spade connectors on but it still didn't work, so I ended up using left bulb feed to switch a relay to light right bulb as a temporary measure while I work out if this Zafira is worth keeping. Mechanic thinks that since headlights are front UEC and indicator interference is from rear module, that it can't be related. He's suggest it could be steering column module (CIM) but not sure.

Any ideas? Thanks!