I replaced the stock 5 pin to a 4 pin ECU orange box and when I try to start up it seems to start then die. I have a four pin ballast resistor. Should it be changed to a two pin type. What ohm reading should I get across the resistor to check it. Thanks.

http://www.moparaction.com/tech/quest/JOSHING.html go to this site it might help.BOB

I am sure the wiring is correct because all I did was replace the ECU. The ballast resistor is good and I have spark from the coil but it seems to loose spark when I crank it and release the key to stop the starter motor. How can I trouble shoot that.

The end of the 4 terminal ballast w the brown wire, connect the brown wire to the other wire on that end & retry it. EDIT I reread your post & you have continuity on both sides of the ballast? did you have this no start prob & that's why you got a new 4 pin ECU? If the ballast has continuity & there's no fire at the blue loop end in run (ign1) I'd trace back to the ign sw for the open & I'd start by seperating the bulkhead & checking the 2 brass terminals for that (run) circuit for corrosion