cruiser54

And the voltage there was over .5 AC volts?

squeaky3

well after putting on a new mopar crank sensor i was only getting .2 ac volts at the ecm, so i drilled the holes a lil on the one that was on it..even though it is aftermarket, i drilled the holes a lil bit just enough so the screws had a lil play, then bolted it up and i have .6 ac volts at the ecm connector

but still dont have spark out of the coil....so im thinking either its the ecm it self...or the ignition control module under the coil

any way to test either of those?

cruiser54

Possibly is the ECM then. If you're going to the JY, get one out of a 1989 or 1990 with the part number ending in 428.

squeaky3

hmm guess i have 2 bad ecm then....sounds like ill have to go to the junkyard and see if there is any there

cruiser54

Well, it could be, or the wiring between the ECM and ICM/coil.

T85konrad

I had a similar problem with my XJ, but for me it was bad spark wires, but did remove the icm and slean the connections? When I removed mine they were dirty and spread too far. Idk if u tried this but that's what helped me.

squeaky3

both icm and coil are new along with wires and plugs

can anyone find exactly what voltage and such im supposed to have on the wires?

that way i can find out if it is wiring or a computer problem

squeaky3

heres the wiring diagrams if someone wants to save it and put the info on it then upload it again that would be great

squeaky3

anyone???

just need some insight on what voltages i should see where to tell if i have a real wiring problem or computer problem

DFlintstone

Your coil/ign has 8 sockets? 3 front, two in the middle three to the rear?

First front green (instrument/tack)
Next black, grounded
Next yellow, 12 volts from the key (Ign)

first middle yellow, about 5 volts, (with),the key (Timing input)(Ign Interference out-put)
no wire

no wire
no wire
no wire


So there's those 8 on my 90 Renix. It's just using the first 4 of the 8

squeaky3

ok thanks, i have all that at the ign module, i dont remember what kinda power i had on the first wire but i know i had 12v on the yellow and 5v on the single yellow one

DFlintstone

You got me. This won't tell you the coil is good, but might tell you if it's bad...
Seems you have absolutely verified your CPS signal is making it to the ECM. I'm trying to learn here....don't know if a bad "synk coil" in the dizy can cause a no spark. Maybe it can Faulty new coil or the ecm? You did try a known good wire right off the coil primary...Hopefully Cruiser OR SOMEBODY can chime in here.
I'll do some looken on no spark and that sync coil.

Suppose Cruiser would have brought that up it could cause your no spark.

cruiser54

Sync signal in the dizzy on a Renix has nothing to do with ignition. I'm thinking somewhere between the ECM and ICM. Wiring? Bad ICM?

squeaky3

pretty sure the coil is ok, i remember checking the resistance of it and pretty sure it checked out ok, tossed on the old coil just to make sure

im thinking it might be the icm too...even though it is new, but its lil over 100 for the one from autozone but it has a lifetime warrenty

DFlintstone

Oh..no big deal, just fyi..I put both the analog and the digital meter on that second yellow wire and cranked it. Just a tiny voltage drop. Wanted to see if the analog might dip,,or something..nothing.

Also "eco mike" on another forum has posted momentarily shorting his CPS wires would make his Jeep start. He had a long standing intermittent start problem. (I think he fixed it by getting his CPS voltage up around where yours is)