Right here's the latest and it's a big post.
Friday
I got back in the van to take it to wheequick and the warning light had stopped flashing. (engine cold so as expected, this makes me believe that it's temp related rather than air intercooler blockage).
We changed the ECT sensor at wheelquick ( one in the block ) more as preventative than believing it was the the problem.We ran th van for ages trying to get it to fail and of course it wouldn't.
Saturday
I took it camping on Saturday morning, weather V.Hot and drove it over to the yorkshire dales hilly and single track 80 miles + with full kit for both of us, ababy and dog after about 50 miles the warning light came on again. it would bairly pull skin of custard. So we pulledover I messed around with the sensoron top of the van with the ignition on and the scavenger fan kicked in, ignition off and it ran for a good 5 -> 10 mins and the warning light stopped flashing and van back to normal.
I've a none standard cover over the top of the engine as sound profing put on by the previous owner so when at the campsite I took this off. Believing that this may be blocking airflow to the top sensor next to the handbrake.
Engine temp does not move passed 11 o'clock
Sunday
Packed up all the kit. Drove another 50 miles through some very hill country single track lanes (really stressing the van in hot weather, with air con on full) no warning light (feeling smug
)
Spent a couple of hours in yorkshire maybe did another 25 miles. then set off to come home 120 miles after an hour on the A1M (70 -75 mphish) heading to the M62 80miles to go flashing glow plug again
I stopped at the services did the disconnect on the sensor thing and cooled the van down. but 25 miles from home it came on again.
Monday
I've rang the mazda garage to see if they have a engine bay temp sensor in stock and waiting for the call back. had the call it's not a good part number.
The way I see it is it's either a faulty sensor, a pants connection or a dodge earth somewhere.
I've had a look at the loom across the top of the handbrake bit and traced it towards the dash and can see no damage.
where are the earth's for this circuit located on the car ?
does anybody have the circuits and are located in the northwich area ?
Anybody had the same issue ? and if so what fixed it ?
Thought it rang a bell as to being something to do with scavenger fan, couldn't remember what, so came inside to check the forum/factsheets, then had a silly thought, I'd disconnected the interior light feed from the leisure battery last night ( to see if it was causing a drain on my LB), so I tried plugging it back in - hey presto - problem solved 
Don't understand why & not going to try, don't really care, just glad it wasn't anything more complicated 
just thought I'd stick it on here in case it comes in useful to someone 
