2001 Jeep Grand Cherokee 4.7 V8- Symptoms crank no start, no fuel no spark, no communication with engine computer - can communicate with tranny, abs, etc.. All fuses ck ok, ASD relay not coming on, relay checks ok and has battery power going to it. Computer is not grounding relay! 5 volt reference circuit was 2.5 volts. Checked & cleaned all known grounds. Unplugged all known sensors in 5 volt reference & still could not communicate with computer! Installed new computer & still no communication & now 5 volt reference is at about .5 volt. Reinstalled old computer still shows .5 volt on 5 volt reference circuit! Any ideas!!!

 

Cps? Maybe?