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Discovery 2 V8 weird faults - help please


plasticbadger
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Hi all, I'm hoping for suggestions on a weird fault on Mrs PB's Disco V8. It's a late Series 2 with the 4.0L Thor V8 and auto box.

There's two faults that don't happen at the same time, but may be inter-linked.

Fault 1 is that a couple of times while driving the green 'M' and 'S' gearbox lights on the dash flash, along with the 'D' in the speedo and the red light on the gear stick. A warning 'bong' sounds. Turn it off and on and it's fine. It drives fine while the lights are on.

Fault 2 is more common, it has happened regularly for the last week. About 2-4 miles from cold the truck will suddenly just die. The engine revs fall and the engine cuts out. No coughing or missing, just falls to stall. It then won't re-start for between 1 and 5 minutes, it just spins and doesn't fire. No lights appear (the engine management light is on ALL the time due to a dead secondary air pump). Once re-started the fault doesn't happen again, or at least not within the 10-20 mile runs we've been on. It's only happening from stone cold.

I've checked some obvious things and the truck had a recent (300 miles ago) full engine service. I don't believe the gearbox oil has been changed and on these later trucks there's no way of checking it easily.

Any helpful thoughts?

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The most common M&S fault is the WXYZ switch on the side of the gearbox that sends gear lever/cable position to the ECU, either out of adjustment or kaput.

No idea on the other fault, my 13 years of Thor V8 motoring were trouble free in the engine department while Td5s died all around me :)

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Crank position sensor. Causes the M+S flash and the cut out.

Located near the starter motor on passenger side and can be a pain to get to.

Read the DTC and confirm it though.

I agree with the diagnosis, however, in my experience, it doesn't tend to throw up a fault code. I tend to use live data to look at the rpm signal after it's cut out, if the sensor has failed, you'll likely see 0/very few rpm when cranking.

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  • 9 months later...

I just thought I'd update this, as I hate threads like this that have no resolution!

The faults were all down to the Crank Position Sensor. I think the fault codes it was flashing up were incorrect speed input and no speed input on the gearbox ECU. It seemed that the CPS would drop out, the engine keeps running, but the gearbox kicks up a fault. I fitted a new CPS and instantly fixed, lovely. Then a couple of weeks ago it did it again! New Land Rover (Bosch) genuine CPS fitted this time and all fixed. Serves me right for buying the cheapest one off eBay :wacko:

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