Series 3 series 3 - Intermittent Starting Issue.

Hi folks,

I’m completely new to mechanics and I’m hoping to get some advice on a strange issue with my Series 3. Here's what's happening,

I recently got the car running and took it for a drive a few days ago. When I returned to the garage and parked, I tried to start it again, but there was absolutely nothing, no lights on the dash, no click from the starter motor, nada!

Then, about 40 minutes later, I tried again, and it started on the first attempt. After that, it wouldn't start again for the next few days.

Here’s what I’ve done so far:

1. I checked the battery but it was a new battery I put on it a few weeks ago.
2. I cleaned the battery terminals and cables to make sure there was good contact (there also seemed to be a second ground wire that wasn't connected to anything so I connected that to the frame.
3. I had a look underneath the car and noticed a loose wire hanging from the alternator. I thought this might be the issue, but when I went back today to investigate the alternator and figure out where that loose wire connects, the car started perfectly without any issues!

It seems completely random, and I’m not sure where to start troubleshooting. Could the loose wire be part of the problem? Or is there something else I should check?

Any advice would be great, thanks!

If you have a look at the series 3 workshop manual in the link below that’s essential to maintain properly
It has the wiring diagrams in there too to check what the dangly wires are for
Your starting problem sounds like bad connection/ poor earths
I would start at the starter solenoid and clean all heavy connectors and washers till bright and shiny.
The clean the thin wire off the solenoid inc. Lucas terminal and make sure it crimps on tight.
Remove bottom of fuse box cover and steering column shrouds to check the wires on ignition switch tight too.

I replaced my fuse box recently as the terminals were loose giving intermittant connections,
By wiggling them with ignition on you might get the dash lights com8ng on if you find the bad connection

You should have a multimeter to check voltage on battery when cold engine not running, should be 12.6v
With engine running and alternator charging voltage should be 14.5 volts or thereabouts

You can also chase where the 12v supplies are and where they should be

Ignition switch. Or relay.