Ignition/ charging system problem?
Turbo Mini Forums

Hi

've got a bit of a problem with one of the Minis. Eventually I'll probably sort it out myself but maybe somebody will be able to give me a tip on it, as currently I'm out of ideas. So this is what is going on:

SC 1,3 lump with Megajolt ignition. Origanal harness came out of early 90 carb model but I did a lot of changes on it o fit
Megajolt in a passenger compartment + fuse box + relays etc.

The core wiring however is original, it was unwraped and checked out prior to fitting it to the car, charging part of the wiring is original and every change I made to the rest was well thought through (I'd like to believe so at least ).

The problem itself is the car still running after switching ignition of. Not a running on. So far I know that the ignition wires are feed back from the alternator brown/yellow wire after ignition is switched off. Charging light comes on when ignition is turned off (only when engine is running). Disconnecting either intrument cluster or alternator shuts the engine down.

I tried 3 different alternators know so I guess we can rule that option out.
I tried 2 different instrument clusters.
Disconnecting ignition switch does make a difference.

My other ideas to check tommorow are:
-poor ground connection on the engine, but it is cranking without problems
-poor ground on the alternator
-something wrong with the wires connecting the alternator to the starter motor - however it is charging 14.0V
But since it is working ok in terms of charging I don't think any of the above is the case.

I think I should also mention that I have most of the additional stuff added to the car wired via relay triggered by the ignition switch. Once it closes the circuit it stays closed, I used probe ligth to check if it still remains live on the trigger side of the relay and it did, but the bulb was dimmed so I'm 100% sure the current was lower than 12V there (might have checked it but can't recall know, it was a few days back).

So any thought?

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

Where is the EDIS powered from? Sounds like it has a permanent live feed, so the engine carries on running even though the other circuits are dead. What unlatches your latching relay?

There was a problem with other Leyland cars in the late 80's, I don't remember it specifically affecting Minis (I remember MGs and Triumphs particularly) but the symptoms are the same and you do say a 1990 loom....

It was a sneaky backfeed from the alternator terminals back through the ignition warning light, just enough to keep the ignition powered.

The simple test is, if the engine keeps running with the key turned off, pull the ignition warning light bulb (only) out of its holder. If the engine stops as soon as the bulb is removed, it's the same issue.

I know it's a long shot but it's a very simple test.

The fix Leyland did was to put a diode in the warning light circuit so the ignition switch still energises the alternator field (forward through the warning light) but the alternator cannot feed anything back through the warning light.

Schrödinger's cat - so which one am I ???

Solved it today. It was exactly as you described it. I thought that diode was already in the alternator but apparently not.

Back feeding was strong enough to keep the relay energised therefore all of the ignition powered devices where still on, I left that part of the loom original an used the wire that was originally feeding coil + terminal (non balasted of course) to trigger the relay.

Today I cut the the wire that feeds the dash and connected it so it's feed via the relay along with pump, additional fan and whole ignition system. The relay now opens the circuit once ignition is off, and back feeding is so low that it's not enough to keep the coil or EDIS or anything else working.

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

Schrödinger's cat - so which one am I ???

We had this with the metro van. Used to have to pull a relay to stop it!

If something is worth doing, it's worth doing half of.

On my SPI, the diode is also in the loom, about 6” from the alternator plug.

I wrapped the loom some time ago now so I won't be checking any time soon, not this one at least, but I don't recall anything on the wire that would caught my attention and I checked it inch by inch.

I do however have a second one that I stripped and cleaned to be used with another car. It's from the same period of time except it's one with ballasted ignition wire and this one doesn't have a diode fitted. So I guess they left factory that way.

For now I've got the problem cured. If it appears again I'll put a diode somewhere near the alternator plug and that should do the trick once and for all.

Thanks for tips. I didn't find any simular topics here or on the tmf forum so maybe it'll be useful to somebody else in the future as well.

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0