No spark at coil

Lack of spark at coil could the ignition relay be the culpert??
Thanks, Sloth

I don’t believe so. I think the ignition protection relay only powers ancillaries, not the ignition system itself.

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Model year is critical for that subject.

Hi Kirbert: My Jag '89 xjs cpe…(early model before Marelli)… I show only 3.5 volts at green ignition lead…I checked the battery and terminals all are up to specs… naturally the power amp unit gets little power and I am confused…would the ignition relay be the culprit??
I would like to avoid digging the relay out (under fuse block) if possible.
Thanks, Sloth

That’s more likely the ignition switch itself. Disconnect the battery, then turn the key back and forth from OFF to START about 50 times. Reconnect battery, remeasure power at ignition lead.

Hi again Kirbert: This ignition assembly has me confused…my model is the last one before Marelli, therefor not a key that fits into the steering column. It has it’s own little panel and what I surmise has one small screw on top of panel and a rubber gasket that hold the cyl. itself to the plastic panel. (note I could be wrong)

Funny how a model for only six months could have so many variables…Regards,Sloth


Not sure what you’re asking, but the problem with getting the ignition switch out is a set of security screws that are supposed to be installed by tightening until the heads break off. You may have to drill them out. Replace with conventional socket head screws to make it easier next time.

The mechanical tumbler can be separated from the electrical switch, and you can purchase just the switch. I don’t recommend doing so because the new one is likely as bad as the old one. Rather, pry it open, replace a bunch of copper rivets between contacts and terminals with brass screws and nuts, and solder everything to ensure reliable connections. And “tin” the contact surfaces, unless you have the capability of silver or gold plating them.

Clean the prongs in the CPS plug, below oil fill cap.