98 Dodge 1500 w/318 ECM/PCM problems
 

I have a 98 Dodge truck with the 318. Not long back I had a problem starting the truck. No spark. Took it to couple different garages and finally revealed that I needed a new computer. Bought a couple from a company online (3) before getting one that actually worked. Drove truck sparingly for couple months and battery kept going down. After using the boost mode on charger one time the same symptoms came back. Would crank but no start. Purchased another ECM from another company. Cranked up first lick. Worked fine for couple of months and noticed that lack of driving or whatever was causing battery to go down again. Used the battery charger a couple of times without problems on 2 amp trickle charge. Went to start yesterday and yep, you guessed it battery very low and had to attach charger. Moved the charger setting to 10 amps after letting sit a while on 2 amp trickle and the motor kept kicking trying to start until I let off the starter. Put the charger back on 2 amp trickle for 3 more hours and now I get the same old symptoms again. I have the sickening feeling I have fried another ECM some how. Any ideas? I am ready to put this truck or myself out of misery! Thanks for any help. Frustrated.

check for bad connections underneath your main fuse box in the engine compartment

You do know that the ecm has to be programmed with your VIN right?

Yes, ecm was programmed with VIN etc..... plus gave him the numbers off the original ecm that came with vehicle.

Do you mean the connections going to the fuse box? If so, will check them out this evening and attach OBD meter to see if any codes are showing.

I'd look into the charging system and battery (and of course grounds as mentioned).
But....
You said in your post that the battery was dead again after sitting a couple days,so something is drawing power that should not when the key is off, check and make sure your glove box light is off when the lid is shut. All this charging and draw on the battery constantly is not good for it, and can potentially kill a cell or two.

no, i meant underneath the fuse box.. you gotta take it out and look underneath it

Bad cell on battery would do that also. You can have your battery checked to rule that out.