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Best Answer cal844 , 22 March 2020 - 04:14 PM

Yes you could just run a new piece of wire as a temporary solution for diagnosis. If the issue is the wire I'd just run it neatly along the loom, then cut the white/red wire back and cap it so it cant be used. Go to the full post


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#1 Eds.mini.lulu

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Posted 22 March 2020 - 11:21 AM

So just need some advice/clarification.

I have a 1993 Mayfair.

When I turn the key to start nothing happens at all.

Voltage at battery is 12.65v
I have 12v at ignition switch (brown wire)
I have 12v at starter motor
I have 12v at starter relay (brown wire)
I have swapped the starter relay for a known working one (flasher relay)
I then checked the switch feed at starter relay white/red wire didn't get a reading. Then got the other half to turn the key to run still didn't get a reading. Should I be getting 12v at the switch feed when the key is turned?

Is this all pointing towards a faulty ignition switch?

Is there anything else I can be checking?

I also have a power probe thing. I have used this to also check for power and also the earth's at the starter and relay all seem ok.

Any help would be appreciated

Ed

#2 unburntfuelinthemorning

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Posted 22 March 2020 - 12:46 PM

I can't think what the back of the ignition switch looks like.  I think there are exposed soldered connections where the wires go into the switch. 

 

If the brown is live (as it should be as brown is permanent live) then use a short length of wire and touch it to the brown with one end and to the red/white wire with the other.  If the starter relay now operates then the ignition switch is faulty.

 

Other thought, is the car an automatic?  If so there's an inhibitor switch which makes or breaks the current in the red/white wire and that may be faulty.



#3 Eds.mini.lulu

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Posted 22 March 2020 - 01:18 PM

No car is a manual. Also I have a sealey power probe which can provide power to circuits. Is this a suitable way of providing power to the circuit I'm worried about the ampage of the circuit I do have some spare cable but it's only rated to 8 amps would this be suitable in this case?
Ed

#4 unburntfuelinthemorning

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Posted 22 March 2020 - 02:03 PM

The red/white wire to the relay will only be low current - 8 amp wire'll be plenty.  However the power probe sounds ideal, never used one myself.



#5 cal844

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Posted 22 March 2020 - 03:14 PM

Use the probe on the red/white wire at the back of the ignition switch, apply power down the red/white wire, the engine should crank over whilst you apply power. If it doesn't then you have a broken wire somewhere in the loom.


I have carried out the above to fault find.

#6 Eds.mini.lulu

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Posted 22 March 2020 - 03:15 PM

They are a great bit of kit got recommended it on here. Wasn't expensive either great for solving electrical issues.

Anyway.
So I did as you said. When I put the probe on the red/white wire at ignition nothing happened. However when I then did the same where that wire goes into the starter relay had the engine turning over.
So I'm assume it's going to be either the switch or the wiring between the ignition and the relay.

#7 Eds.mini.lulu

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Posted 22 March 2020 - 03:18 PM

Does anyone know how and where the immobilise is wired into the circuit could this be a potential issue. I have had issues with it before.

#8 unburntfuelinthemorning

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Posted 22 March 2020 - 03:41 PM

Ah now the immobiliser, it could be that if it cuts the starter motor.  Can't help with that though.  It sounds like a break in the red/white wire whether that's caused by the immobiliser or just a straight forward break.



#9 Eds.mini.lulu

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Posted 22 March 2020 - 04:06 PM

To test this theory could I run a new piece of cable from the ignition to the starter relay. I don't think it is the immobiliser because the cars been fine all last year it's been laid up over the winter but I dont use the immobiliser to be honest.

Just wondering if the new cable from ignition to starter relay will work as not sure if the immobiliser makes any difference.

#10 cal844

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Posted 22 March 2020 - 04:14 PM   Best Answer

Yes you could just run a new piece of wire as a temporary solution for diagnosis. If the issue is the wire I'd just run it neatly along the loom, then cut the white/red wire back and cap it so it cant be used.

#11 Eds.mini.lulu

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Posted 22 March 2020 - 04:27 PM

Ok thanks any idea what gauge or rating the wire would need to be. I may run a test wire but when I replace ill get the same colour and cross section.

Was looking at something like this.

https://www.autospar...-20-11-amp.html

#12 unburntfuelinthemorning

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Posted 22 March 2020 - 10:02 PM

Ok thanks any idea what gauge or rating the wire would need to be. I may run a test wire but when I replace ill get the same colour and cross section.

Was looking at something like this.

https://www.autospar...-20-11-amp.html

That'll be well up to the job.



#13 Eds.mini.lulu

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Posted 25 March 2020 - 03:16 PM

Sorted, ran a new wire from ignition switch to starter relay. Fired first time, well after about 5 seconds. Not bad considering hasn't been started since October.
Love learning new skills as part of mini ownership




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