Ignition coil -ve terminal and 6.8k ohm resistor

[DarkMatter]

I understand that the ignition coil -ve terminal connects to the ECU at pin 39 via a 6.8k ohm resistor using a white/black cable. Is the 6.8k ohm resistor at the coil end or elsewhere? (my guess is that it is at the coil end)

The reason I want to know is that I want to fit a gear shift light and the device I've bought needs to connect to the coil -ve terminal, so to avoid running a cable to the engine bay I'd like to make the connection somewhere accessible e.g. near the ECU. Can anybody say whether it is likely to matter or not which side of the 6.8k ohm resistor I connect to?

Thanks.

[blitzracing]

That depends on what the shift light expects as an input. Typically you might see a 150v spike on the coil primary, so this will be limited to something managable for the ECU electronics to deal with with the resistor. Its also very likey there will be some sort regulation on the input of the ECU (more than just a resistor) so its quite likely the spike will now be too small to trigger the shift light if it expects 150 volts. Ive got a trace somewhere of the ECU input, Ill dig it out when I get home.

[330p4]

Andrew there will be some form of Zener diode at the ecu to clip this voltage to 5 or 12V I suspect
Ian

[blitzracing]

Ive checked the traces it seems to be peaking at around 22 volts on the ECU input. As suggested I would think this would be dropped further once inside the ECU.

[DarkMatter]

Thanks for the replies. I'll try to get in touch with the supplier to see what they say, failing that I guess I could just connect it at the ECU end and see whether it works and if not I'll run a cable direct to the coil.