How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • Go back-and-forth until satisfied
    Rate the answer you receive.
Ask Matt Your Own Question
Matt
Matt, Mechanical Engineer
Category: Classic Car
Satisfied Customers: 26523
Experience:  IBEng hons Mech engineering, in auto industry 22 years
12772297
Type Your Classic Car Question Here...
Matt is online now

Hi - I have a 1994 Mini Cooper and went to start the car this

This answer was rated:

Hi - I have a 1994 Mini Cooper and went to start the car this morning. There was a click from the solenoid and the electrical systems just went dead. The battery seems to be ok and I have tried jump starting the car with no difference from another known good battery. Nothing seems to work but on occasion the side lights do work again for some reason and the ignition lights come back to life. Trying to start the car at this point results in the failure again! I have checked as many fuses as I can locate - the 30 amp ones under the bonnet are all good and seem to have 12 volts on them. Any suggestions gratefully received.Thank you in advance - Graham Miller
Hello

I'm Matt and I'll try to help you with this

If the car's not cranking then first check it can turned over by hand so double checking for any mechanical issues
If OK then check that the main battery cables are on tight and the terminals are clean and bright. Do the same for the engine / gearbox earth strap.
Then follow the main positive lead back to the engine and down to the starter motor, and check the connection at this end as well.

There should also be a small wire to the motor which should have 12V when you're turning the ignition switch to crank. If the 12V isn't there, check back along this wire for damage to the insulation or corroded connections

This 12V feed comes directly from the ignition switch so this may be faulty and need replacing

Check the resistance of the main positive lead that runs down to the motor as anything more than a few ohms and it should be replaced
Don't forget to try a jump start from another car / battery as its possible the battery is poor, if you have a voltmeter a healthy battery should read 12.7+V

also try substituting the battery for another as I've known a very flat battery to drag down the system voltage too far even with jump cables

one other thing to consider is that the immobiliser is faulty and preventing the starter from being enabled - however if the dash / ignition lights are on then this usually means that its off

If this is all OK then its possible the car needs a new starter motor
Customer: replied 8 years ago.
Hi Matt
I've. Been through most oft this including using a known good battery . It's almost as if something is failing in the electrical system but I'm at a loss as to why everything stops working including the side lights when they appear to be supplied straight off of the battery and would not seem to be controlled by the ecu etc. I guess I'll have to take the front grill off of the car and trace the 12 volts through to the lights in more detail to see what's happening with them as there must bea clue there?

Regards Graham
Hello Graham

Ok if the main battery earth is good then also check the state of the ECU earth's that bolt to the engine block and head with some ring terminals

there's also a main chassis ground wiring loom point close to where the subframe bolts on at the front this combines a lot of functions so also well worth checking

the issue sounds exactly like a bad earth to me so all and any earth pointws need checking and cleaning / tightening etc

Matt and 2 other Classic Car Specialists are ready to help you