Been on a massive electrical odyssey this afternoon,

Horn and reversing light not working.

I had taken the steering wheel off and put it back again since the last time I used the horn.

And from my carb messings I knew fuse number 9 protects those two items and the idle cutoff solenoid.

I do now have an idle cutoff solenoid but is wired in parallel with electric fuel pump. Wonder if it is same as supplied the Pierburg's 2e3 part channel heater.

Anyway, fuse number 9 looked fine.

Replaced it with brand new 8A just in case. Tested horn had conductivity. Tested horn push off the car. Removed the wheel and tested horn push in the steering wheel. Reconnected wheel and horn push, turned on ignition the horn beeped. Tightened up steering wheel. No more horn beep. Removed steering wheel, Cleaned clock ring and regreased it. Cleaned slide contact. Rechecked horn push. Rechecked fuse. Refitted steering wheel. No honk. Checked horn. One of the blade connectors had fallen off! Cleaned and refited blade connector. Horn works.

Phew.

Checked reverse light bulb. Ok

Checked blade connectors on reverse light switch. Ok.

It's got to be the switch in the gearbox. I'll connect across both blade terminals tomorrow.

Do I need to fix it before MOT test?

Horns a test item, reversing light isn't. Put a rhd light unit and bulb holder in and it should give you a pair of fog lights.

Thanks.

I already swapped to UK rear lights so I'd need LHD left for twin rear fogs.

But I do need to see when reversing in the dark sometimes or I would never have known it was bust (like last night).

The gearbox switches do gunk up over time, so you're right, bridging it is a fair way of checking that. They're a pretty generic part on VAGs so should still be available, the only catch is later ones have a two pin multiplug rather than spade connectors.

Right. Might be a good time to change the smelly old gearbox oil anyway.

Actually I should check the wiring too. There are wires and some Scotchlok insulation displacement connectors (cause I didn't know any better back then) to swap fog and reverse lights from left hand to right.