Series 3 ignition switch failure?

Is it a common failure that the switch momentarily drops +15 when coming back from the ‘start’ position?

Has anyone had any luck breaking one down and cleaning it?

If it’s anything like the ignition switch in the XJ-S, I have long recommended breaking it down, replacing the copper rivets that secure the contacts inside to the terminals on the outside with little brass machine screws and nuts, tinning the contact surfaces with a soldering iron or possibly even silver solder, and possibly soldering the contacts, screws, nuts and terminals together. All easy to do as the base is ceramic, you can solder all you want with no worries about melting anything.

And yes, we have a terrible amount of trouble with that #@#$%^ switch. In fact, when a member complains that he turned the key and nothing happened, the first suggestion is always to go out there and turn that key from OFF to START and back about 50 times to clean all the corrosion off those contacts.

‘…drops +15’ is somewhat cryptic to me, Paetersen…?

The set-up is spring loaded - and may just need some lubrication? The most common failure is failure to make the required connections - ref Kirbert…

xj6 85 Sov Europe (UK/NZ)

YUP. Swappewd mine out with a NOS switch.

So many gremlins went away.

Source: David boger at everydayxj. good guy. good stuff reasonable pricing fast service.

I tried to fix mine. Ugh, it flew apart lost too much!!!

+15 is switched positive power. +30 is unswitched AKA constant positive power. +30 is all the stuff that gets battery voltage regardless of the position of the key, +15 is all the stuff that gets battery voltage only when the key is in the ‘run’ or the momentary ‘start’ position. If faulty contacts drop the +15 connection it is the same as physically turning the car off.

Wow. Where’d you pick up this nonsense? It’s not voltage, it’s just confusing. I’ve certainly never heard any such convention before.

I’m mystified as well.

Maybe terminal designations marked on the back of the switch? I never looked…or have forgotten.


Aye. AKA white wire. Switched. Brown wire. Always hot.

The gist of the ign key operation, Paetersen, is that it is spring loaded from ‘crank’ to ‘run’ when released. And if intended circuits are not getting power in ‘run’, or other relevant positions, it is certainly an internal switch fault - which, if not exactly common, does happen…

xj6 85 Sov Europe (UK/NZ)

“this nonsense” is industry standard nomenclature. There’s a DIN designation for the naming convention that ALL auto manufacturers use. Educate yourself: DIN 72552 - Wikipedia

Well, at least that explained why relay terminals have those 87 numbers.

It was the + sign that confused us all.
Interesting document by the way.

To follow up:

Took the lower panel off the drivers footwell and put the key in the RUN position. Jiggled key, dropped +15. JIggled wiring, dropped +15. Pushed on back of switch and +15 would reliably come back. Took switch out and 1 of the 3 assembly crimps had broken off, allowing for intermittent contact on the +15 circuit. Disassembled it, cleaned the contacts and reassembled, substituting a dab of quick set epoxy for the (now 2) broken crimps.

The dodgy connection is gone and the switch seems to be working as it should, no more jiggling-creates-shut-off. Time will tell…

So? Where are the pics? :slight_smile:


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If that is you, did you double for Rowdy???