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Retro Fitting Mk 2/3 = Dead Car.

Started by Utopian2 , Apr 03 2024 08:15 PM

Best Answer Utopian2 , 11 April 2024 - 06:19 PM

I'm sorry to say that people might not learn much, and it's a bit embarassing, but here goes.

 

I spent the last two evenings reading up on the electrical side of things.

As part of this it was mentioned that you should always check your multimeter before each use, I hadn't does this for a few years (that's Lexus for you...), and they had always checked out fine.

 

When touching the points together, I got a figure of around 0.5 Ohms - rather than zero or near-zero and not far off the reading when testing each fuse.

I also read about 'Phantom Draw' (or 'Drain'), which suggested that the battery may have been constantly running down all the time I was trying everything else (again the duff multimeter not helping much).

 

So, as a last attempt before sending it to the Mini specialist, I thought I'd take the battery out and charge it in the house, to keep an eye on how discharged it was.

It took 10 hours to fully charge a bog-standard ~40AH Halford's battery, obviously meaning that it was completely flat (6 Amp (rms) charge).

 

Anyway, so I put the charged battery in and tried the car this afternoon - the lights etc worked, which suggested it wasn't as bust as I had assumed, but still no cranking.

 

I figured that just replacing every fuse & the battery would be a small fraction of a tow away and repair, so I got a lift to the little side street car parts place, bought the specified bag full of fuses and a Yuasa 075 Battery with a 4 Year Warranty (from GSF).

 

I unscientifically replaced all the fuses in the car and it started first time, on the 'original' battery!

 

So, a big thanks to 'KernowCooper' for his encyclopaedic knowledge of the Mini's electrical system, and electrics in general.

 

Although the old battery was able to start the car, KernowCooper states that a battery once completely flattened, it isn't worth having, so I think I'll put the Yuasa 3000 075 one in it's place - £69 from GSF as a 'click and collect' price seemed ok, and ups the capacity by a third to 60AH.

 

But it was the fuses that did it - for £10!

 

I'm only sorry I can't add much to the pool of knowledge, without having identified the specific fuse causing the fault - but at the price, who cares really.

Thanks everyone, and good luck to you all.

 

 

 

 

 

 

 

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#16 GraemeC

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Posted 05 April 2024 - 07:00 PM

I’m not sure what that means - it’s appropriate whenever doing any work on the car that involves the electrical systems, especially if you’re not confident.

Anyway, if it has been disconnected ensure that all the terminals are clean and tight. Unfasten the negative cable from the boot floor and clean the ring terminal and boot floor to nice shiny metal with some emery paper, then reassemble and make sure everything is tight.

#17 Midas Mk1

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Posted 05 April 2024 - 07:28 PM

You really need to follow the next steps I posted earlier today. if your not using a multimeter you are just wasting time, you need to follow the path of power to see where you loose voltage.


You need to check the ground continuity, then live feed continuity to the starter solenoid, this is a crucial next step. Without either you will never have any power.

If you’re not confident, electrics are really not something to mess with blind and i’d advise seeking help.

I’d also advise to consult the haynes thoroughly before doing any further work.

My bet is you have shorted a live to ground, or there is not a good ground on the 12v to body mount.

For reference I work on high end ev’s daily fault diagnosing, just switching random fuses or wires isn’t going to do anything other than cause further confusion. Likewise you need to be following the mpi wiring diagram, without it you might aswell put a finger in the wind.

Edited by Midas Mk1, 05 April 2024 - 07:51 PM.

#18 Utopian2

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Posted 06 April 2024 - 10:07 AM

I’m not sure what that means - it’s appropriate whenever doing any work on the car that involves the electrical systems, especially if you’re not confident.

Anyway, if it has been disconnected ensure that all the terminals are clean and tight. Unfasten the negative cable from the boot floor and clean the ring terminal and boot floor to nice shiny metal with some emery paper, then reassemble and make sure everything is tight.

I meant to say I have disconnected and reconnected the battery many times in the process of fitting new kit and fault finding, but I couldn't guarantee I did it every time.

 

I have checked all the fuses with the multimeter, it shows 4.5v across it when on the car, 13v when -ve is disconnected.

My best bet is a short to earth from doing the lights, or from the connectors to the fuel tank.


#19 Utopian2

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Posted 06 April 2024 - 10:09 AM

I need an isolating switch.


#20 Davidmt

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Posted 06 April 2024 - 11:37 AM



I need an isolating switch.

 

A bit late now but I always fit one to any car I am playing with - this is the one I have fitted to the Mini.  

 

Attached File  20240406_123154.jpg   91.19K   2 downloads

 

I have a spare isolator in the garage that you can have - PM me your address details and I will send to you.  Use it to switch the earth lead on your battery.  You may need an additional lead to connect the switch but easily available from eBay etc.


Edited by Davidmt, 06 April 2024 - 11:38 AM.

#21 gazza82

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Posted 06 April 2024 - 12:53 PM

I have checked all the fuses with the multimeter, it shows 4.5v across it when on the car, 13v when -ve is disconnected.


Take the fuses out and test each one with the Ohm setting. That will tell you if you have continuity.

Not sure how you get 13v across the fuses if the negative earth lead is disconnected at the battery .. I'd expect closer to 0v. There will be no circuit through the car.

#22 Utopian2

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Posted 06 April 2024 - 01:12 PM

Sorry when I say 'it' I meant just the battery when disconnected - that bit is ok.

#23 sonscar

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Posted 06 April 2024 - 01:15 PM

Firstly,disconnect every thing you have rewired.Then check things like the headlamps.If they do not work then get them working.Use a wiring diagram and draw on a paper only the one circuit you are working on.When you have that one working do the same to another.Do this until everything is done.
Remember that you are not fixing everything at once,you are biting off one thing at a time.Try not to be overwhelmed.Good luck with learning new skills,Steve..

#24 Utopian2

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Posted 06 April 2024 - 01:28 PM

Thanks Davidmt, that's very kind of you, but I'm going to get an overpriced one from Halfords this afternoon,so that I can make the most of my last day off tomorrow.

I don't understand how the electrics are dead, but no fuses are blown.

My next thing I will check is if the fuel pump is open circuit.

If that checks out ok, I'll call in an auto-electrician next week.

I can finish off the soundproofing in the meantime.

#25 Utopian2

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Posted 06 April 2024 - 01:30 PM

Thanks Davidmt, that's very kind of you, but I'm going to get an overpriced one from Halfords this afternoon,so that I can make the most of my last day off tomorrow.

I don't understand how the electrics are dead, but no fuses are blown.

My next thing I will check is if the fuel pump is open circuit.

If that checks out ok, I'll call in an auto-electrician next week.

I can finish off the soundproofing in the meantime.

#26 Davidmt

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Posted 06 April 2024 - 04:25 PM

If the electrics are dead but no fuses blown then either the battery is dead or the main cables are disconnected or damaged.  Highly unlikely anything you have done with the lights will have caused such an issue as any shorting on the light circuit should just blow the fuse on that circuit - the rest of the car should still work.

 

As probably suggested above check the cables are securely attached to the battery.  Then check you have a good connection and voltage to the starter/solenoid - can you jump an extra battery?.  If there is an issue with the lighting circuit try removing that fuse to remove any potential short - if you have not touched any other circuits the rest should still be fine.

 

Check the earth straps on the battery to the chassis and also the same to the engine.  These things are just a process of elimination and perseverance!


#27 Midas Mk1

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Posted 06 April 2024 - 06:12 PM

[quote name="Utopian2" post="3763506" timestamp="1712410216"]

Thanks Davidmt, that's very kind of you, but I'm going to get an overpriced one from Halfords this afternoon,so that I can make the most of my last day off tomorrow.

I don't understand how the electrics are dead, but no fuses are blown.

My next thing I will check is if the fuel pump is open circuit.

If that checks out ok, I'll call in an auto-electrician next week.

I can finish off the soundproofing in the meantime.[/quote
]

Your guessing. Please stop, think.

#28 Midas Mk1

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Posted 06 April 2024 - 06:15 PM

.

Edited by Midas Mk1, 07 April 2024 - 04:02 AM.

#29 Midas Mk1

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Posted 06 April 2024 - 08:54 PM

.

Edited by Midas Mk1, 07 April 2024 - 04:02 AM.

#30 Davidmt

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Posted 06 April 2024 - 09:04 PM

Whatever you do...please let us know the outcome and what happened. All helps others.
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