An elecrical issue, see if you can solve it......

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bzrse7en
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An elecrical issue, see if you can solve it......

Post by bzrse7en » Tue Apr 07, 2015 7:15 pm

Ok, so i can start car on the ignition switch, the ignition switch turns the ignition on and off in the usual way. But once running the ignition switch will not shut off the engine, it keeps running. The only ways of stopping the engine is to either stall it, or use the battery isolation switch.
I know the alternator is feeding the ignition somehow, just not sure how yet. :-?

eke_zetec_rwd
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Re: An elecrical issue, see if you can solve it......

Post by eke_zetec_rwd » Tue Apr 07, 2015 8:30 pm

Where have you wired the big wire off the alternator to? not the Ignition post of the key?

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nz_climber
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Re: An elecrical issue, see if you can solve it......

Post by nz_climber » Wed Apr 08, 2015 7:53 am

Would need a bit more information, like mentioned above, where is the main feed from the alternator wired into? How is the alternator wired? How is alternator wired in the original engine?

I know mazda put a diode in the charge light circuit, so that is probably to stop the alternator feeding back into main system, so could be something simple to look at.

bzrse7en
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Re: An elecrical issue, see if you can solve it......

Post by bzrse7en » Wed Apr 08, 2015 8:45 am

Big alternator wire is connected to battery isolation switch - on the battery side. I had it on the other side a while ago and had same symptom with the isolator - it would keep going.
A good idea about the diode, the ignition light shines bright when ignition is off and engine is running.

bzrse7en
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Re: An elecrical issue, see if you can solve it......

Post by bzrse7en » Wed Apr 08, 2015 8:05 pm

Ignition and EFI is wired the usual way with a relay controlling the ECU, this then feeds into another relay which feeds fuel pump, coils and injectors.
What I am thinking at the moment is these relays are the usual 4 pin type. I'm considering going to a 5 pin relay, wired with the contacts in the off position earthed, that way it pulls any induced voltage to ground. I am pretty certain OEMs do it this way.

Patrick

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nz_climber
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Re: An elecrical issue, see if you can solve it......

Post by nz_climber » Wed Apr 08, 2015 8:54 pm

I haven't done that on the 4 engines I have wired and never had a problem, I would be looking to sort out why the charge light doesn't work, then actually isolate where the voltage coming from to cause the ecu relay to stay on.

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techtoys
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Re: An elecrical issue, see if you can solve it......

Post by techtoys » Fri Apr 10, 2015 5:17 pm

Sounds like the alternator/charging circuit is wired to the wrong side of the key switch. Or you've got the FIELD and SENSE wires from the alternator swapped, which achieves pretty much the same as my first sentence (as well as explaining why the alternator light doesn't work).

See the diagrams at http://mywiringdiagram.blogspot.co.nz/2 ... grams.html and note that the ignition switch and power feed to the ECU and fuel pump would be further downstream than the Fusebox.

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Re: An elecrical issue, see if you can solve it......

Post by bzrse7en » Fri Apr 10, 2015 5:52 pm

techtoys wrote:Sounds like the alternator/charging circuit is wired to the wrong side of the key switch. Or you've got the FIELD and SENSE wires from the alternator swapped, which achieves pretty much the same as my first sentence (as well as explaining why the alternator light doesn't work).

See the diagrams at http://mywiringdiagram.blogspot.co.nz/2 ... grams.html and note that the ignition switch and power feed to the ECU and fuel pump would be further downstream than the Fusebox.
Thanks for that, though you might have misunderstood me. The charge light works perfectly, that is, until the ignition is turned off and the engine continues to run, at this time, the light comes on. Which, on reflection indicates maybe it isn't the alternator at all.
I must say, i haven't looked at it in a week, so i'm just shooting the breeze - wasting everyone's time maybe.
I had wondered if the fp relay is getting some inductance from the coils, holding it in. This happened to me ages ago when i fitted a relay to a coil on a 6v vw. The dam thing wouldn't turn off unless stalled. Not sure if it was the proximity of coil and relay or voltage from the primary windings causing the problems.
Best i have a play.

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Re: An elecrical issue, see if you can solve it......

Post by bzrse7en » Sun Apr 26, 2015 8:47 pm

Seems it has fixed itself, engine will turn on and off as it should. I am pretty sure it was like this at the start. I can only assume fault was / is a sticky relay.

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