1983 Jag Xj6- engine shuts off odd and abruptly. Bad ignition switch maybe?

Howdy all,

So while messing with my ac relay I had the car on and idling great to test for blower fan activity. While that issue is discussed in another thread of mine on this site, my car did something unexpected. It just abruptly shut off. No starving for fuel, no clangs, no gut wrenching sounds or shakes, it just shut off as if i flipped the key. After that It took me 6-8 key turns to get it back on and idling, once again at a great pace with no fluctuations in rpms. It idled for 8-10min then died in the same manner again. To not risk more damage or killing my battery I have not tried to start it since.

I suspect the electric ignition switch, but was wondering how to test or if their might be other possible issues?

I can say all fuel injectors are new, pump works great, fuel filter is good, and i get fuel return to the correct tank. When i try to crank the starter engages normally. It just will not go.



In short, Nikolas - it cranks but won’t start?

If so; jumpwire from battery ‘+’ to coil ‘+’. This will bypass the ignition key - just to see what will then happen. If this does not eliminate the problem - it gets more interesting…:slight_smile:

Just keep your battery charged…

xj6 85 Sov Europe (UK/NZ)

Yes sit cranks but has trouble starting. Ill try you idea this afternoon.

Aye, that is my favorite. Jump 12v to coil +.

Another. when it quits. Get the meter or test lamp. With the key on, probe for volts at coil +.

I’ve noted the You tube mechanics have neat probes for _ or - !!!

All beat he way we did it way back. + to ground to get a spark!!!



So I just found out from my Grandfather in-law (original Car owner) that the ignition coil on the car is the coil from the dealership in 1983… So i tried jumping as you all have said nothing happened. regardless of it it is the coil being the issue or not, I do believe its time for a replacement. Ill report when the new coil comes in next Tuesday or Wednesday and I can get it installed!

That the engine quits instantly when it quits does indeed imply an ignition failure, Nikolas…

Connecting a spare spark plug to any plug lead, is the common ign test with a non-start. No spark while cranking, no ignition - but the cause may be various…

But the jump says your ign key is not the problem…

xj6 85 Sov Europe (UK/NZ)


don’t rush it! I’ve replaced what is likely the original coil of my 1975 car just last week and I’m not even sure whether it is broken. Chances are you bin a high-value original Lucas part for a low-quality and cheap replacement part with a fancy name and brighter color …

My money would be on the spark as well, but the ignition lock is safe for me, as you write that you operate the starter right after it stalls. If the ignition lock is failing, the starter won’t turn, even the relay won’t click

You have to try 6-8 times for a restart? Then address spark! Have you checked dizzy cap, contacts and HT wires? Sudden death also indicates either power out (intermittent loss of +) or intermittent loss of ground. Check all ground connections - also a standard remedy for all kinds of electric issues …

Good luck


75 XJ6L 4.2 auto (UK spec)

So changing the coil did not lead to the car running again but it did help me confirm a bad distributor cap. will be changing as soon as I can get a new one!

So spark from the coil wire, but not to any spark plug? Brilliant, very happy for you!

Yep! Made me happy too

Nikolas Faust,
Fighting Texas Aggie Class of 2019