I have a dodge ram 2500 4x4 5.7 ltr that is frying PCM. On #4 PCM now. Has fried #3 coil two of the times. The last PCM lasted ONE DAY

Thinking it HAS TO BE in the wiring somewhere.....

You have a bad ground connection, my friend....grab a coarse wirebrush and undo the lug at the end of the black battery cable (other end from the clamp end) undo- the bolt and wirebrush 'till shiny, the lug as well....because they are dissimilar metals and are dealing with weld amperages....a thin layer of corrosion (the blue spark) leaves traces of carbon and does things to the flow of electricity...."brown out" a condition in which the ECU is unable and throws a check engine light for every last little item~

varying voltages and varying amperages are not a problem with an airplane...seems like we've devolved using inferior (cheap) materials and people will suffer as a result.

the ground connection will "save the day" with any computerized module....suffer from "eddy currents" {not a popular guitarist} and magnetic influence....anyways these are delicate electronics....not Drop Forged in Cleveland~

That would fry the PCM 4 times and #3 coil two times?

Varying times between blowouts

Has been to two mechanics (including Dodge, they installed last PCM yesterday) Ran on Dodge diagnostics computer several times now and all it reads back is coil

I would say the problem is in thewire that comes from pcm. ASD relay turns on coils by suppling 12 vts to them. the PCM triggers the coil on the groung/negative side of coil. Now lets just say that the wire comming from the PCM shorts out some where to ground. the coil would stay turned on and cause a coil melt down. Now that the windings in coil are all melted together, the spot where the wire is shorted to comes ungrounded. you will get a shot of 12 vt. back to the PCM, knocking out the coil driver. I would start by running a new wire to the coil from the PCM. cut wire at PCM to eliminate wire in harness. dont just splice into it. hope this all makes sense to ya. Ive seen this happen several times. Hope this helps......

cut wire at coil also

replacing the ASD is the mend here?~

the asd(auto shut down) powers up all the coils...all eight of them, all injectors, alternator field,fuel pump relay and other things. I really feel its wire between pcm and that one coil.

i have a smillar problem on a 2.7 but mine does not pulse i have steady power to # 3 cylindre need help it will not fire

It should have steady power as long as it's running. The pcm grounds the coil. So either the connection is loose at pcm, a connector, or coil. The wire between coil and pcm could have an (open) in it. Or pcm is bad or coil is bad. Use an ohm meter and ck continuity of the coil wire between pcm and coil.

Thanks Guys. It was a short in the wiring. The shop finally pulled the whole wiring harness and went over it inch by inch (after they ate the cost of a few PCM's) Since wiring replacement we haven't had any issues