Problems starting & limp mode

Hey there, just got a new Disco and am having some issues with starting and limp mode

A few days ago, car was cranking but wouldn’t start – no lights were on. After 3-4 goes it went.

Next time I tried it, it wouldn’t go at all. A day later it did but after about 10 minutes driving the S and M lights came on and it went into limp mode.

I then test battery and it was 12.3v… it looked pretty old so I bought a new one, cleaned terminals and was getting 12.8v from both terminals and leads. Car started but after 10 minutes back in limp mode…

Now when I go to start it the S and M lights come on and it cranks but won’t start.

From my Googling etc it seems to be that it could be one of a few things:
• Alternator
• Crank sensor
• Grounds
• Air box and hoses
• XYZ (but I did the rear wiper test – and that worked, though not sure if this is reliable)
• Transmission fluid

I know I need to use a code reader but my mate with one is away at moment. Any suggestions on easy ways of solving/ruling out any of these?

Thanks in advance!

I'd rule out the XY switch. The car won't crank if this is playing up.

Cool thanks, good to have one crossed of the list!

You've missed off the wastegate actuator and the wastegate itself, which can get sticky, this will send it into limp home mode.
Then there is always the possibility of the dreaded P clip on top of the Transfer box which can have erratic effects when the insulation wears inside the loom, invisibly until you take it apart and solve it.
Does the limp home start after you have revved it a bit or gone up a hill?
What a ****, I somehow thought you had a TD5.
Duhhh!

Hi thanks for your response, no the limp mode occurred on the flat - first time when I was cruising at about 70km and second time when I had reversed out and was in 1st with barely any revs. Don't like the sound of the dread P clip already!

MattR78 said:

Hi thanks for your response, no the limp mode occurred on the flat - first time when I was cruising at about 70km and second time when I had reversed out and was in 1st with barely any revs. Don't like the sound of the dread P clip already!

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I'd ignore the P clip for the mo.
Sounds more like crank sensor to me but others with degrees in electrickery will come on and help sort you out.
Have you taken it off cleaned it and put it back on?
You never know!

Ok happy to ignore dreaded P clip for now! Nope, haven't done anything beyond new battery at this point... new to disco and not the most mechanical person ever but like to give it a shot! Thanks for your help. Will have a look at crank sensor ASAP.

MattR78 said:

Ok happy to ignore dreaded P clip for now! Nope, haven't done anything beyond new battery at this point... new to disco and not the most mechanical person ever but like to give it a shot! Thanks for your help. Will have a look at crank sensor ASAP.

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I don't think they are expensive but don't take my word for it as I am too old skool and am a long way down the learning curve on electronics on modern cars. Give me points, a coil and a condenser any time!
But have a look here
https://www.aulro.com/afvb/discovery-2-a/162615-causes-solutions-flashing-m-s-lights.html

Stanleysteamer said:

I don't think they are expensive but don't take my word for it as I am too old skool and am a long way down the learning curve on electronics on modern cars. Give me points, a coil and a condenser any time!
But have a look here
https://www.aulro.com/afvb/discovery-2-a/162615-causes-solutions-flashing-m-s-lights.html

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Thanks again, yeah I can get one for a reasonable price by the looks of it - though I am keen to try to diagnose the issue before I replace any more parts! Will check the link, cheers Matt

MattR78 said:

Thanks again, yeah I can get one for a reasonable price by the looks of it - though I am keen to try to diagnose the issue before I replace any more parts! Will check the link, cheers Matt

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One thing to be aware of is that the battery terminal connections on a D2 are ffing stoopid. When fitting them you need to undo them to the max, then bang them down the terminals with a hammer and a socket or somesuch, then tighten them.
Only way to get good constant contact. These vehicles are SOOO sensitive to voltage.

Now see my earlier post, now corrected because I have only just checked your profile to see yours is petrol.
dooper that I am.
Still much of what I posted still holds, I think!
I'd best go to bed now!!!

Stanleysteamer said:

Now see my earlier post, now corrected because I have only just checked your profile to see yours is petrol.
dooper that I am.
Still much of what I posted still holds, I think!
I'd best go to bed now!!!

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Cheers mate! Yeah I think the connections are ok as getting same volt reading from terminals and cable harnesses (or whatever they are called)

DefenderPilot said:

I'd rule out the XY switch. The car won't crank if this is playing up.

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Thanks mate, will keep working on the growing list of other possibilities!

Definitely invest in a Land Rover specific diagnostic tester.
To me it sounds like a bad crank position sensor is going bad (left hand rear corner side of V8). Check by cranking over engine and if no RPMs showing then it’s bad or going bad. Replace with a Bosch part # ERR-735.
As previously mentioned Inspect all of you battery and cable connections for corrosion and/or just being loose.

JUKE179r said:

Definitely invest in a Land Rover specific diagnostic tester.
To me it sounds like a bad crank position sensor is going bad (left hand rear corner side of V8). Check by cranking over engine and if no RPMs showing then it’s bad or going bad. Replace with a Bosch part # ERR-735.
As previously mentioned Inspect all of you battery and cable connections for corrosion and/or just being loose.

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Thanks mate. Just tried and RPMs only show after engine starts (of course it started this time) but not during ignition. Is that what you mean?

Yes. Sometimes it’s easier with a diagnostic tool to digitally see your rpms when starting the engine.
If your Disco started fine and then dies later after the engine heats up it sounds like a bad CPS.

JUKE179r said:

Yes. Sometimes it’s easier with a diagnostic tool to digitally see your rpms when starting the engine.
If your Disco started fine and then dies later after the engine heats up it sounds like a bad CPS.

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Awesome, thanks again

Update: Early days, but I replaced the crank sensor yesterday and have not experienced any issues yet - though have only taken her for a couple of spins. Note: Out of all the guides I read about changing the sensor, not one mentioned what a PITA the harness would be... If anyone reads this it is best accessed from above, and you need to push it back towards the firewall to get it out of the bracket first before disconnecting. I would recommend attaching the sensor itself before trying to reconnect harness, and pushing sensor end of plug against the bracket when reconnecting as the cable wants to twist away the whole time (unless there is a way better method I missed in my reading!). Thanks again for all your help, Matt

Well done!

Glad to hear it is sorted now.
I guess I should have mentioned it was a PITA to remove and replace the CPS on the V8 as I did it from the bottom and reaching upward.
Some people have wrapped aluminum foil around the wiring to keep down the exhaust heat attacking the CPS.