2007.5 lmm no crank/no start

pkeith25

New member
Dec 2, 2025
3
2
3
Alabama
Let me preface this by saying I have searched the search bar and tried several solutions with no results yet**

I have a 2007.5 lmm i bought to use motor in something else,
When you turn key on engine light is slow to show up. It won't crank. Service board shows service 4x4, and some others, abs light is on
Gauges dont show anything at all, even when I crank motor on starter
Important codes are ecm doesnt communicate with bcm, tcm doesnt communication with bcm, ebcm doesnt communicate with ecm, ecu or bcm.

Motor will fire right up with key on and jumping starter

So I have read through the threads and here is what I have done so far.
New ignition switch
Cleaned grounds on driver side frame
New batteries
Cleaned main fuses wires the two 175s and 125. And replaced fuses.
I tried grounding ecm like I found in another thread** didnt do anything
Had a radio fault from vcim so I unplugged radio.
Checked all fuses for continuity
Checked gmlan it was at 60 ohms.
I have started tearing into the wiring loom but no broken wires yet just trying to figure out if its a bad bcm or not since ill be doing away with it at swap
Appreciate yalls thoughts
 

pkeith25

New member
Dec 2, 2025
3
2
3
Alabama
Welcome

Can you communicate with the ECM using a scan tool? Codes?
I assume im communicating with it motor will stay running, I have a u140 code no communication with bcm. Ecm tab on scanner pulls up information and vin so Im about 90% sure
 

pkeith25

New member
Dec 2, 2025
3
2
3
Alabama
Update to this i went through a bunch on the other forum verified everything was good from fusebox to starter. Checked all fuses couldnt find any broken wires. Scan tool showed communication fault from tcm to bcm, ecm to bcm, ebcm to bcm so after checking all grounds and everything. I noticed scan tool wasn't showing vin on bcm even though it showed good nothing on the scan tool was functional on bcm so I ordered one from Lincoln diesel specialties and installed today and fired right up on key