Ecm part question M1078a1

[jmenende]

Howdy folks.

So it seems i have a bad ecm and im currently looking for a replacement. While taking the ecm out, I came across this module that was not connected. Anyone knows what it is?

 

[Keith Knight]

That is the EMP / electromagnetic pulse filter that caused problems so they bypassed it. Basically it caused problems without having an EMP.
It’s garbage remove and throw it in the trash.

 

[jmenende]

Got it. Just toss it then.

 

[Keith Knight]

Yep

 

[Ronmar]

Yea it was either for EMP or to suppress electronic noise. They installed filters on several of the circuits, anything with a motor(wiper, heater, windshield washer pump)…

 

[GeneralDisorder]

What tests have you performed to determine the ECM is at fault?

 

[jmenende]

What tests have you performed to determine the ECM is at fault?

I connected it to my cat et software and it would not read. Tried same process with another lmtv and that one read fine. Sent it off to ecm king.

 

[GeneralDisorder]

I connected it to my cat et software and it would not read. Tried same process with another lmtv and that one read fine. Sent it off to ecm king.

Did you check powers and grounds at the ECM 70 pin chassis connector? It won't communicate if it doesn't have power.

Chances are GOOD that the patch cable used to delete that EMI/RFI suppression box in your first post is trash and that kills both the battery power and chassis ground to the ECM causing them to go offline including no coms. That was disconnected by MWO while in service and a patch cable was installed to bypass the module. Unfortunately the patch cables themselves are hot garbage and are often the source of this exact problem and it is usually misdiagnosed initially because no one learns from history and digests all the service information and knowledge gained over 30 years of operating these platforms.

If they say it's bad - and they probably will since at least the onboard battery (inconsequential) will be dead - DO NOT buy a replacement from them or have them program another module without confirming that they KNOW what software is required for a military truck application and how to setup all the parameters - especially if it's truly dead and they can't recover a backup image. The vast majority of CAT ECM repair shops have no clue how to setup the ECM for an FMTV application. You should have asked here and just sent it to me. I program ECM's for specifically these trucks and these trucks only and it's often me doing it at additional cost to the customer after some other shop has F'd it all up.