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trebor · 12th December 2019, 12:59

Hi Matt
If you want to communicate with thermis test off the car you do need a 1ohm resistor on the k bus wire, when the switch opens it pulls the voltage up to 12v and when it is closed it pulls it down to 0v.
It needs to be a resistor so the switch can overcome the voltage otherwise when closed and connected to 12v it would blow the fuse

12th December 2019, 12:59	#3
trebor This is my second home Rover 75 CDTi Connoisseur SE & MG ZT Saloon 190 Join Date: Jun 2007 Location: Coven Posts: 12,523 Thanks: 526 Thanked 1,877 Times in 885 Posts	Hi Matt If you want to communicate with thermis test off the car you do need a 1ohm resistor on the k bus wire, when the switch opens it pulls the voltage up to 12v and when it is closed it pulls it down to 0v. It needs to be a resistor so the switch can overcome the voltage otherwise when closed and connected to 12v it would blow the fuse __________________ www.midlandsnanomeets.co.uk Robs Car Gallery Coven near Wolverhampton WV9 2000 Cowley Built Rover 75 2.0 V6 Club SE/ Atlantic Blue/ Sandstone/Walnut (daily driver) 2003 Land Rover Freelander 1 TD4 HSE Helsinki Blue/Black Leather (swmbo daily driver)