Intermittent starting problem

[steve m brown]

a few weeks ago I came out to my car and after deactivating the immobilizer the usual dash lights lit up but when key turned nothing happened.
I checked all fuzes which were fine and tried again and it worked and has done since.
Today after a short drive and left to stand for approx 30 mins I had the same problem, dash lights on but not turning over.
Again, I tried checking fuses but it didnt seem to work then just as about to give up it fired up.
Once home, I systimatically pulled a fuze out to see if I could make it happen which of course didnt work! I cant make it not start.
cant find the fault
Any ideas?
Steve

[Pauln]

If starter motor is totally silent, ie not even clicking, might be worth checking the starter motor relay to see if that's faulty and/or is getting power when you turn the key.

[steve m brown]

Do you know where that hides?

[Peter Gidden]

Starter relay is in boot behind carpet. Although extremely rare for them to fail.

No pint in guessing what it might be.

Keep a DVM handy and next time the problem occurs get it out and check for volts at starter relay when cranking.

Could easily be immob. at fault.

[Poker Face]

Give your battery connections a check over as I had a similar situation on my wife's car.
It may well be something else but worth checking. She had an intermittent starting fault too.

Just remember to use an insulated spanner or disconnect the earth whilst you check the live, I've seen a spanner cut through a panel because someone couldn't be bothered to disconnect a battery (this was on a helicopter but the principle is the same, live contactor to chassis earth).

Good luck I hope it is something simple like this.

[steve m brown]

Hi guys, thanks for your replies so far.
located the relay, all looks fine there, no loose wires.
One other thing I forgot to mention... the 1st incident had occurred over night and weirdly the dash clock time was wrong by hours! suggests battery but its well nipped up and fine.
is it usual to wire the immobilizer via the dash clock?
what fuse would the dash clock be into?

I took a close look at the immobilizer contact strips and they did look a tad furry... given them a gentle buff... watch this space!! so far working fiine today but will wait till we in middle of nowhere with no signal to be naughty again

[chrismit]

I had a similar issue and it ended up being a break in the wire going to the positive terminal from the ecu. battery end.

[coopey]

what make of immobiliser is it?

just had the same issue and now it's been bypasses there's no problem any more

[2mad]

This is very imortant .. no click when you turn to key from the boot starter relay .. means immobilizer or circuit problems .. not often a starter relay fails .. if it has you can bridge it and fire the starter from the relay.


Hope you sort it , get the mulimeter out

[IMR2T]

Mate the only time mine doesnt fire is when the starter seizes.

If it happens again and you can bump start it then its time for a new starter.

If you cant bump start it you know its immobiliser.

[Peter Gidden]

is it usual to wire the immobilizer via the dash clock?

The immobiliser would never, ever be wired to include the clock.

what fuse would the dash clock be into?

The DOME fuse. Which is permanently live even when car switched off and locked up.

[steve m brown]

to update...
Checked all you suggested to no avail, even cleaned out the contacts on the immobilizer switch... it did it again a week later.
Gave in and got auto electrician in. FIXED!!!
he has seen this issue before. My mobilizer has a 2 part system; 1 wired to fuel pump and other to ig switch.
He bypassed the IG switch wire leaving just fuel pump live...so far SHHHHHHH!!!!!!!