Hi I have trouble with diagnosing no comm between modules. The relays is clicking when I open or clôose door or when ignition is on. The network shows intermittent short (can low to can high and also to ground but only to ground pins on DLC not on physical metal.) When measured disconnected PCM the …

I would say you have damaged comm wiring. Start searching the wiring looms until you find the short. Likely a rubbed through wire touching ground.

yep, start following wire looms and inspecting for rub points. it’s there somewhere.

What are the actual ohm readings when everything is connected, when just the PCM is disconnected, just the BCM disconnected, and both PCM and BCM connected?

[image] dianiskatomas_191452: When measured disconnected PCM the short was on PCM but also on BCM so when disconnected both of them the network was finally not shorted This would seem to indicate there is nothing wrong with the interconnect wiring. [image] dianiskatomas_191452: Both of t…

I think there’s only two wires in the Can bus. It seems like the best debug method would be to disconnect all the nodes and bus terminators then use a DVM in resistance mode to probe the two wires at node number 1 to make sure each of them gets to all the other nodes , and no short circuits betwee…

[image] ECM not communicating Maintenance/Repairs RESOLVED: Finally after many many attempts I got it to work. The whole problem was 1 diesel injector internally shorted to ground. This injector was shorting also the ECM.

Multiple modules not communicating

Maintenance/Repairs

davesmopar May 11, 2026, 1:00pm 8

Topic		Replies	Views
No communication between modules/car wont start Maintenance/Repairs ford , electrical-wiring	13	390	May 11, 2026
ECM not communicating Maintenance/Repairs ford , electrical-wiring , diagnostics	8	147	May 11, 2026
Electrical short Maintenance/Repairs	2	247	August 13, 2008
CCD Bus system Maintenance/Repairs	14	9436	January 15, 2009
OBD2 scan help (shorts and BCM) Maintenance/Repairs ford , electrical-wiring , engines	6	3030	August 25, 2023

Multiple modules not communicating

Related topics