XJ-S V12-5.3L (1982)
Fig. 1 Lucas twin coil ignition system
1.
Switch ignition on and check voltage at positive terminal of auxiliary coil D.
2.
The voltage should be 12 volts. If voltage is below 11 volts, check wiring from ignition switch G.
3.
Disconnect lead from negative terminal of auxiliary coil and switch ignition on.
4.
Negative terminal voltage should be 12 volts. If voltage is zero, replace auxiliary coil.