cynic wrote:

My '03 Discovery has begun a sporadic fault. Symptom being the engine
management fault light comes on and the accelerator pedal has no effect
although the engine continues to run at tick over. This has happened
twice now at about two weeks apart. First time just before Christmas on
a busy dual carriageway during peak period. I managed to coast up onto
the grass right out of the way of the traffic fortunately or some loon
would no doubt have come to a sudden stop in my rear end. I called the
RAC out and on arrival the fault had disappeared. the engine started
and ran ok so we travelled to a nearby car park where the RAC guy
plugged his "universal" comms laptop into the link but the Land Rover
system would not talk to his set.
He theorised that the fault was transient but would be in the engine
management memory and a Land Rover agency could interrogate it.
Having tried and failed to make an appointment at a reasonable time
before Christmas the problem recurred on boxing day but I found simply
turning off then on again was sufficient to reset the unit again. I am
now due to take the vehicle into an agency next week but they were not
confident the memory would still hold the fault.
Have we anyone in our numbers who have knowledge of the engine
management system on a Discovery 2.5 Diesel and is it feasible to get
hold of the commes interrogation software to run on my own laptop?

A reasonable starting point would be the throttle potentiometer, assuming
the disco uses such a thing as its throttle position sensor.

Might be an intermittent wiring fault or a dodgey pot (or a million other
things, but you have to start somewhere). Try reseating the connectors. If
you can ascertain that it is a simple pot, disconnect it and use a
multimeter to see if it's giving sane and stable readings as you move the
throttle over the operating range.

As you mention, the ECU *should* record its last error at least and Land
Rover should be able to read this out. However, they might try to charge a
full hour's fee (like 80 pounds or whatever) so another approach is to try
a small garage or tuning specialist - such folk have offered to do a diag
dump for me for as little as 15 pounds, until they found out their kit
wasn't compatible with my mouldy old '98 Daewoo.

Don't know if that's of any help or not...

Cheers

Tim