Dear Forum,
I am conducting pinpoint tests of Ignition Coils and the Workshop Manual instructs me to measure the resistance between (say) pin 4 and the Battery Negative Terminal. Now obviously the workshop manual must know that my Battery is in the boot, so does it mean me to test between pin 4 and a suitable earth, please?

 

In theory, the earthing point links to the battery negative terminal via the car bodyshell with no resistance in between, so yes, an earthing point is an alternative if you haven't got a long enough lead. The only thing is there will be some resistance between the two, albeit it should be very low, but if your supposed to be reading a resistance that is also low, the additional resistance of the earth path could give an incorrect result.

 

is there a way to get a baseline reading of resistance so you can discount that in the measurement? determine a range from readings from the other coils? or maybe using jumper cables to extend the lead (again measuring resistance to subtract)

 

Thank you for your post. A good suggestion and one that I tried. The resistance and voltage readings from the other coils were similar, so I have no idea what relationship a resistance reading of 1140 to 1150 has to the more than 10,000 ohms required by the pin test? I accept that these readings may be lower than true, because of the metal between the negative battery terminal and the test pin, but surely the earth being obtained by the test pin is the earth obtained in the engine bay and 1140 seems an awful long way away from 10,000? I might try checking again now that my battery is back to full charge, but AT THIS TIME I HAVE NO DTC'S (and perhaps even more importantly, a beautiful Jaguar XJ8L running beautifully)! So I am very tempted to leave well alone!

 

Check the ignition coil ground circuit for high resistance

Cyl 2 P122, pin 2 (GB) I get - Cylinder 2 coil connector Breen/Black wire.
However, where do I find EM29 pin 08 (GB), please?