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Mystery Electrical Fault


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#16 M I N I

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Posted 03 June 2018 - 01:04 PM

I had an issue with everything dying. 

 

Try changing the earth in the boot, I had a quick release before & the connection on it was rubbish.

 

Also, look for any sign of corrosion in the boot- mine shorted out on some stuff that got kicked up though a hole in the boot!!

 

Maybe check the fuse box for corrosion too? That was caused the issue I had with lights, but could potentially cause other electrical mishaps.

 

 

Hopefully someone on here will find a fix!

 

C



#17 Boycie

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Posted 03 June 2018 - 03:50 PM

The main power cable can touch the exhaust at the front which leads to all sorts of problems.  The heat burns the plastic insulation away which then allows a direct short from the battery to earth.  Quite often, people find the problem in time (before it burns the car to the ground...) but simply tape the lead up and secure it away from the heat source.  This is fine as a get you home fix, but long term, the damp and corrosion gets into the cable to the point it rots away what's left and causes major problems.

Check the main battery cable carefully at the front :)



#18 Thelowrider

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Posted 04 June 2018 - 08:17 PM

Flickering between 4-6v I’d say this is a poor connection most likely going to be the earth. Make sure both terminals on the battery are free from corrosion. Next thing to do is set your multimeter to ohms and check for voltage drop on both cables from the battery. Put one multimeter end on the -‘be terminal and then the other end on the bolt head for the earth if the multimeter shows resistance then there’s an issue in that cable, if not try scratching the multimeter probe next to the bolt into the bodywork to see if an resistance is here if there is resistance then the connection needs cleaning up and reassembling.

#19 KernowCooper

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Posted 04 June 2018 - 11:53 PM

As already mentioned the voltage at the solenoid relies on the complete circuit having a good connection.

 

This is what I would do

 

1.Charge battery and confirm it able to hold voltage under load, and replacing it with a known good battery rules this out, or Get the battery tested

 

2. Check both battery terminals for a good connection, if Top Hat type replace for clamp type

 

3. Remove 5/16 half inch spanner size earth strap to boot floor clean both surfaces and replace, check for verdigre between cable and terminal

 

4. Move to engine bay and check the earth wire connection across the engine stabliser above the clutch end, or below on subframe to engine, If frayed replace, if ok check for verdigre between cable and terminal, Extra earth cables will help.

 

5.Remove the main battery cable from the solenoid (disconnect battery first) check and clean as required, clean starter to solenoid connections.

Check the crimped on connection on the solenoid and the solenoid to starter as they can be a source of high resistance with verdigre on the copper cable to terminal body

 

6. Clean the main Brown 12v feeds on the solenoid to the main power to fusebox and ignition.

 

7. Once all cleaned and confirmed no high resistance on any of those connection causing volt drop, reconnect battery and retest voltage across battery, and then repeat the test on the 12v onto the starter solenoid.

 

8. Thats the complete circuit

 

If your main battery cable has become damaged to be honest I've not seen one cause a 6v volt drop over its length, its usually a high resistance some where in the circuit and the tell tale is when lights slowly dim and fade away. The alternator wont have any bearing on any voltage checks on the circuit listed above.

 

If your familiar with volt drop testing and have a digital meter you could pinpoint where along the circuit is your problem, see FAQs Electrical on how to if your not up to speed on testing Volt Drop.


Edited by KernowCooper, 04 June 2018 - 11:58 PM.


#20 WillCarter

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Posted 25 June 2018 - 08:57 PM

How did you get on with this?




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