Trying to start by itself!!

[Jamsy]

Heard the LC trying to start today so ran outside to find it trying to start itself!
It was locked, keys were in the house and it was cranking away. Went back and got the keys, jumped in and turned the ignition on and it started straight away without turning it to start.
Turned it off at the ignition but it was still cranking away so I had to disconnect both batteries.

Also found that pulling the starter relay stops it from trying to start but there is power at both sides of the relay. Someone said it sounds like a live going back up the wire from a dodgy solenoid?

Got a video but can't attach it using the 'attach files'

 

[Beau]

Sounds like the LC is giving you a signal to drive it more.

Jokes aside, not sure what it could be. A bad relay sounds possible

 

[Higgy]

Christ Jamsy that sounds like a head scratcher.. Where's Jibber Jabber when you need him, He'l have an answer.... In fact where is Jibber Jabber?....... Is the ignition Barrel worn? could be making contact somehow.... Well worn Barrels seem to throw up all kinds of Mysteries... Just guessing Mate

 

[Towpack]

If pulling the starter relay stops it cranking the fault is either the relay itself or further back in the starter circuit. Where exactly are you getting the +12v at the relay connector?

 

[Chris]

Things like starter relays and winch relays need to be mounted the correct way up. The electro magnet pulls in the contact and the springs backs it off. If the spring fails the plunger should not be able to fall and bridge the contact. Ie, it's mounted sort of upside down if you follow. Gravity keeps it open. I don't know your vehicle and its history, but worth determining if anyone has fiddled about with the starter relay to make room under the bonnet.

Very long shot I know, but the relay might be firing due to gravity and a broken spring not a 12v supply.

 

[Jon Wildsmith]

Did you figure this out?

 

[Jamsy]

Still not figured it out Jon, its sat on the driveway. I fit the relay in the morning and pull it before I leave it at night but its stopped doing it which is annoying as I don't want to leave it incase it does it again.

I took it to a garage and they suggested fitting a push button start but Im not that keen, I'd rather just get the problem sorted.
Someone suggested its most likely to be the solenoid shorting over and a live going back up to the relay and holding it closed if that makes sense?

 

[Jamsy]

Things like starter relays and winch relays need to be mounted the correct way up. The electro magnet pulls in the contact and the springs backs it off. If the spring fails the plunger should not be able to fall and bridge the contact. Ie, it's mounted sort of upside down if you follow. Gravity keeps it open. I don't know your vehicle and its history, but worth determining if anyone has fiddled about with the starter relay to make room under the bonnet.

Very long shot I know, but the relay might be firing due to gravity and a broken spring not a 12v supply.

The starter relay is in the relay box under the bonnet at the passenger side which is the original position. I checked the relay and it seems fine although maybe its worth changing to rule it out?
The solenoid with the plunger is on the side of the starter motor so it too is in the original position so I don't think its anything to do with them being mounted upside down.

 

[Jamsy]

If pulling the starter relay stops it cranking the fault is either the relay itself or further back in the starter circuit. Where exactly are you getting the +12v at the relay connector?

Thats what I thought but someone suggested it could be a short after the relay which would put a live back up the wire, holding the relay closed?

 

[Shayne]

Reading this while not logged in and underneath was an article promoting an 80 with the opposite problem which might help you look at it from a different angle The Cruiser won't start "CLICK" - [Leaving Land Cruiser Club]

 

[Jamsy]

I read that Shane, I actually had the same click problem a couple of years ago, changed the contacts and plunger in the starter solenoid which fixed the problem.

 

[Jon Wildsmith]

the switched and coil circuits of the relay are quite separate. I'd forget the power back up the wire theory personally.

You said there was power both sides of the relay - which pins did you test and was that with the relay in place or removed?

You can often remove the cover on those relays and see if anything looks suspicious inside.

The circuit from the ignition switch to the relay is very simple so it would have to be a dodgy ignition switch to connect power to the relay so maybe worth taking a closer look at that / wiggling it etc to see if you can make it do it again ...

 

[Jamsy]

Ok I'll forget the 'power back up the wire' theory.
I only tested with the relay removed. Now that the fault has disappeared Im getting 12v at the top left pin in the picture, nothing else.
With the ignition to ON I'm still getting 12v at the top left but also 9v bottom right. (I guess the bigger pins at the top are the power side and the two smaller pins at the bottom are the control side)?

I had the plastic cover off the relay and there was nothing suspicious looking. I also tried wiggling the ignition barrel but no luck there either.

 

[Jon Wildsmith]

Tricky to diagnose while it's behaving itself!

 

[Grimbo]

My money would be on the contacts within the soleniod .....
Normally this shows it's self when you start it on the key and then it keeps cranking but no reason why if the soleniod was sticking the contacts could just have been touching enough to arc across and form proper contact ,
Take the starter off and remove the soleniod end cover and you will find that the copper contact has eroded to such a degree it allows the soleniod to tip sideways in it's bore and stick .Also the contact ring on the sloeniod will be burnt and pitted .

 

[Jamsy]

Had the starter off today and checked the solenoid, there was a bit of pitting on the contacts but they were in pretty good condition, (I had replaced them about 18months ago). Nothing obvious and the wiring to the starter looked fine. Going to replace the relay next as its quick and easy.

 

[Jon Wildsmith]

Now that the fault has disappeared Im getting 12v at the top left pin in the picture, nothing else.
With the ignition to ON I'm still getting 12v at the top left but also 9v bottom right.

When you turn the key to the start position, I'd expect to see 12v at one of the bottom pins. 9v is a bit odd actually. I don't know which of the two bottom pins should be 12v and which should be 0v unfortunately, but it should be quite clear cut - not one is 12v and one is 9v - that would suggest an earthing fault and the 9v pin should be 0v ...

 

[Jamsy]

With ignition OFF I get 12v top left 0v on the others.
Ignition ON i get 12v top left and 9v bottom right (think you are right about the earth fault there Jon).
Ignition to START I get 12v top left and 12v bottom right.
All checked with the relay removed.

It makes sense apart from the 9v when the ignition is to ON (still doesn't explain how it tried to start with the ignition off and the keys out!).

Any suggestions on where to go from here?

 

[Grimbo]

Forgive me if I'm stating the obvious .....

The bottom pair of wires are the relay coil circuit so the L/H pin should go to earth and the R/H pin should see 12v ONLY with the key at start position.

The top left is a power potential sitting there waiting for the relay to close and make contact and allow power to then go to the top right and then on to the starting circuit .
If you bridge these two wires the starting circuit should be energised and the starter turn .

The fact that you are seeing 9v on the R/H bottom pin with ignition on indicates a poss short to a +12v ignition ON supplied wire ..... you could try pulling fuses and seeing which one makes the 9v drop off ....this may help isolate where the 9v is coming from , clearly it's from an ignition ON supplied source or item

 

[Jamsy]

Yeah that's my understanding of it Grimbo.

When I pulled the 30A AM2 Fuse I lost the 9v and also when I pulled the 20A EFI/ECD fuse.

It also disappeared when the gearstick wasn't in the Park or Neutral positions, so it must be before that interlock looking at the diagram.