I parked my land rover about 5 weeks ago now. 2 weeks ago the alarm started going off for no reason. It went off and all seemed fine. Went to start it about 2 days later and it would not crank. Battery showed 52% but would not crank and when I turned the key the electric fan was going full blast. I charged the battery fully and then it would crank and not start. Tried starting fluid and nothing. Ran battery to 35% but it was still trying to crank with battery that low but put it back on the charger. I checked to see if plugs were firing using a timing light and nothing. I replaced the crankshaft position sensor and still would not start. When trying to start the "M" is flashing (a previous owner had blacked out the "S" and check engine light) and the high temp light stays on all through the crank. I checked the codes and it is reading P1842 and P1843. I reset the codes but the P1843 won't clear. And then I am having trouble connecting to ECM via the OBD reader. have checked fuse 14 and relay in passenger and fuse 2 under the hood and all are good. I have tried starting in neutral and no change

The battery is not the newest but seems ok. I am reading that maybe the XYZ might need replaced, but why? And why was the fan running full speed? I had replaced the alternator in January and I could not connect to the OBD2 then either when it was bad. Should I start with the battery? Why would it just sitting for a month cause the problem?

Note: it was sitting in the driveway and we got about 15" of rain in the time it has been sitting. The sunroofs do leak. It was running fine with no codes prior to parking it. Although it did seem to be having symptoms of the CPS needing replaced.

 

I just got an 1843, did anything come of this?