ZT SW controls issue

[goltho]

Last year, I removed the Kenwood head unit from the ZT and fitted my old VDO unit from the 75, as I was fitting a new Chinese double din unit to it. I found then that I couldn't make the SW wheel controls work as the ZT had the infra-red remote control system built in. So I gave up.

I'm now about to sell the 75, so today I set about swapping the two units over as I'm keeping the double din head. I've got issues on both fits.

1. The VDO's gone in the 75 ok, except for the wipers wiping once when the key is turned to off. The wiring's correct and it's the original unit to the car. Never happened with this unit previously or the Chinese one.
2. The double din unit's gone in the ZT ok except for the SW controls not working. I've checked the (now spare) two infra red wires which have a small (0.3v) voltage when the buttons are pressed, but the head unit doesn't respond to them.
3. There a small connector on the 75 which isn't connected to anything although it's part of the original loom. Pic attached. So the questions are:
* cause of the 75 wiper issue
* how to find a solution to activating the ZT SW controls
* what's the small connector for

Thanks.