After the hack and wiring install to modify the T3 double cab – its a 1983 so has the early style fusebox – and also the simple wirinng options- I cut and spliced the loom from the steering column switches – with very helpful info, wiring diagrams and a step by step from the tech archives at club 80-90
This released the intermittent wiper action in the double cab – super helpful for mild rain.

A ‘luxury’ option that was on some model golfs and passats was programmable wipers – you could engage the wipers and quickly disengage them – wait a few (common options the system understands appears to be 3-20 seconds) then engage them again and the magical relay number 99 will remember the interval and hey-presto programmable wipers –
there is a good write up on https://wiki.seloc.org/a/Wiper_Variable_intermittent that give more technical details – i searched for model code 357 955 531 and got this – next step – plug it in and see if it works as the direct replacement it is supposed to be 🙂