Ok for the basics
2003 Discovery SE "was given by Brother in law that isn't mechanically inclined in any way"
149000 Miles
Engine rebuilt at 97k
Head Gaskets / Top end done last year 2015 at 148000.
Batt is a 550cca "Switching it tomorrow to 750 cca because one in car has reversed cell and won't hold a charge"
Check Engine light is on solid on start up "by being jumped"
Any rev's to motor check engine flashes
goes solid once back at idle
new fuel in tank
Vehicle drives ok just sluggy is all no real violent shaking at all.
Cant access the obd2 codes on my snap-on scanner but scanner does power up on the OBD2 plug "If was a gmc I would think it is a fuse" Is there a fuse in the Rovers that do the same thing?

Anyone with a heads up as to the code retrieval would be a big help

 

there have been some members whom had issues with the diagnostic plug. You may try cleaning with some electrical contact cleaner. These are very picky about having a good battery and nice clean connection especially on the ground. Report back after you get the battery replaced.

 

That was my idea. I am a Ex Master Tech and all I can remember is the bad about these things and their power issues. And the reverse Cell in the battery is a BIG no no for almost any car.

Now my debate is drive it the 40 miles home or trailer it....

 

Bro-in-law likely had driven further in past with light on? If trailer readily available not too inconvenient why not? If not roll the dice.
......

 

Well i did take it out onto a 50mph road to see what it did on Saturday and it was like nothing wrong. But coming out of a 06 Denali that's built up to me the thing was a slug bug. But i am getting good KV on all cylinders and Oil Pressure is normal. So I figure swap the battery out and see what that does first. Then side road it a bit to see if there is anything that comes up and if so Trailer queen it for the day. I will report exactly what I do find because it seems everyone has these issues but nobody really puts a final point on what fixed it other then a few Fuse Box issues "Normal Brit issue with any of their cars"

 

Guess we all need to weed through the read to find all the true resolutions. Looking forward to your Ex report on lack of code access.
......

 

If the check engine light is flashing then you've got a miss on a certain percentage of cylinder fires. Cant remember the exact amount, but it is enough to be considered damaging to the vehicle. Misfires will melt your catalytic converters in a heart beat. I wouldn't drive it if I were you.

 

My obdii connector started losing connection because it is always connected to a heavy cable and is no longer in its slot (for support). I did the caveman thing and mashed the wires in from the back the connector and it came back to life. The wires may just be a little stretched.

But I THINK (just bare recollection from my parts rover that is now long gone) that group of cables goes straight to a connector on the ecm. Seems like a replacement would be easy to find at a Boneyard and you could just run them to the glove compartment or back through the dash.