DIYEFI.org Forum

I can pick up these Volvo coil packs pretty cheaply, I wondered how they look for use with wasted spark with FreeEMS/Jaguar. I can't find any helpful m$ pages discussing their behaviour. They look like they have NPN BJTs in the S60 wiring diagram:



1. Ignition signal
2. Return to EMS?
3. Ground to engine
4. Switched, fused 12V

If they're any good, will I need access to a running vehicle to figure out what logic voltage is required?

If the diagram isn't simplified, then it's a pretty safe bet you need 12v+resistor. If you really want to be sure, you need to insert a resistor in line with the drive to one of them, and watch BOTH ends voltage. In the past other people with insufficient electronic skills have incorrectly measured ~4-5V at the device and concluded "5v drive". What's actually happening is that ~5V is the end result of 12+resistor+current draw.