in september this year i posted a request refering to g\cherokee non start, no commuication with the ecm ,plus no engine check light no instruments, and no reference voltage from the ecm, but i did have perminant feeds and switched feeds and good grounds, i posted request on a couple of jeep sites but this one is the only one to reply, with i might add some very useful information and help.i am quite sure that the problem has been solved it looks like a cps internal fault closing down the ecm.
The way i found it out was by doing this .and without a wiring work sheet

1 disconnect the jeeps ground cable

2 connect a slave battery to the positive terminal( cable only)

3 connect a snapon probe to the slave battery

4 check for reference voltages( now have them)

5 reconnect the jeeps ground cable(remving the slave battery first)
( reference voltages have now disapeared)

6 disconnect the sensors one by one(map\idle control etc) until the voltage returned, and in my case happened to be the cps

7on doing the above the engine check light and the instruments were restored( new cps on order)

8 many thanks to dk sob 81 and to this brilliant site

cyril(from england)

How did you get the voltage? Did you use a DVOM? What are the parts cost in England?