RR Classic cutting out

[pka15]

G'day,
My 94 Classic is cutting out unexpectedly. Recently while my daughter was driving the engine died and wouldn't crank over at all.
The car was towed home and by the time I looked at it, it has started every time. I haven't been confident to drive it since it stopped but it starts and runs, no problems.
I was wondering whether the anti-theft unit could be the cause? I had a VP Commodore do similar years ago and the immobilizer unit was the culprit.
Has anyone had similar problems? my only other thought were a start relay?
Thanks, any help would be appreciated

[DoubleChevron]

heat sensitive "something". I'd start with the ignition module and pickup inside the dizzie.... even the coil could be getting hot and not working. Get it nice and red hot under the bonnet and see if it stops, you should be able to find the issues while its broken by spraying the bits with cold spray.

[pka15]

heat sensitive "something". I'd start with the ignition module and pickup inside the dizzie.... even the coil could be getting hot and not working. Get it nice and red hot under the bonnet and see if it stops, you should be able to find the issues while its broken by spraying the bits with cold spray.

Thanks so much for the input.
I was thinking similar except, when it happens, it won't even crank ie turn key nothing except dash lights.
I've had it running in the garage for at least half an hour on many ocassions since but it sits there running beautifully

[PhilipA]

I would be looking at the main fusible link in the positive battery cable.
Regards PhilipA

[DoubleChevron]

Thanks so much for the input.
I was thinking similar except, when it happens, it won't even crank ie turn key nothing except dash lights.
I've had it running in the garage for at least half an hour on many ocassions since but it sits there running beautifully

battery terminals.... check the connection both side of the main battery cables too.

Oh, unless you have good strong dash lights and everyhting else works. In this case, the starter motor is on its way out.

[Tins]

Starter motor wouldn’t explain why the thing cuts out in the first place.
Fusible link, check all the earths etc. I would try a voltage drop test between the engine and the chassis, also between the battery and the engine connection and the battery earth and the chassis.
Just my thoughts.

[Mercguy]

It's time to check ALL the earth points and clean them properly.
After that, check the main positive leads from battery to starter, Main fusible links and the alternator.
If any look sad, take the time to upgrade them now with new fresh copper (weldflex to starter is a very good idea)

Then you need to check ECU harness, fuel pump and Ignition / MAF wiring for cleanliness.

Remove the immobilizer connections that disable the ign/fuel. It is a common issue - especially in aftermarket installations in all european manufactured vehicles where it's a retrofit.

Check your ignition switch contacts / replace - because this ultimately will fail if it has not been replaced. factor in a 5-10 year lifespan for an aftermarket ignition barrel / switch.
If the key is good, chances are the switch is munted and any 'key jiggling' is a sign it's not great. An ignition switch should have absolute verifiable and securely defined detents for each position. Sloppy detents are a sign the switch can be failing - when it does, you will get exactly the symptoms you described.

But it's a Range Rover, so the guarantee is that you will face numerous electrical conundrums and every siongle connection in the vehicle needs to be systematically inspected and tested to ensure longevity.

Everything under the instrument cluster and dash is guaranteed to be messed with by someone at some stage during the vehicles life - and do not be surprised if you find butechered wiring, poorly taped connections with wire twists for connections or those absolute bollock-pain inducing scotchlock connections which should be banned and users hung drawn and quartered for their indoctrinated usage in the auto-electrical industry.

</rant>

good luck. get yourself a really good digital multimeter if you do not have one already - and I mean a decent one, not a jaycar or repco or supercrap auto meter. You want a proper quality unit from a reputable brand.
good example: EEVblog BM786 Multimeter
– EEVblog Store (https://eevblog.store/products/eevblog-bm786-multimeter)

Not specifically endorsing, but brymen is a good brand and not many people would spend the $1K plus for a good Fluke or Gossen outside of an electrical career.

[pka15]

Thanks to everyone's help and sorry for not replying to everyone sooner. Life has been hectic [bigsad].
I think a failing battery was the culprit in the end. It was intermittently playing up then after the car sat for weeks the battery finally died completely, shorted internally.
I did bypass the immobilizer also to be sure. I also sent the control unit for the Immobilizer/central locking to England and had it repaired, reprogrammed and supplied with two new remotes. works a treat now.