Chosen Solution
My background: Former Chrysler technician, 17 year employee @ Alldata.com as Senior Technical Editor, ASE certified Master Tech (plus numerous other certs) Vehicle: 1971 Plymouth Barracuda Engine: 2006 Chrysler 300 6.1 Hemi with original engine harness, ECM, & FCM Transmission: Tremec 6 speed manual 200 PSI compression pressure while cranking. The ECM has had the SKIM (security) option deleted by All Computer Resources, Inc. I have triple-checked powers, grounds, 5 volt references, and wiring to both modules. Also has 12 volts & 2 grounds at the OBD connector. The CAN high & low wires measure 60.8 ohms. Voltages on those lines measures 2.61 volts and 2.43 volts, respectively. Crankshaft Position Sensor and Camshaft Position Sensor are making their respective outputs, as measured by an external oscilloscope. The ASD Relay & Fuel Pump Relay do power up when the key is turned on, then the fuel pump relay waits for a cranking signal, then it re-energizes when the engine is cranking. Has power to the coils & fuel injectors through the ASD relay.
Problems: When I plug in the scan tool, it powers up but can’t communicate with the ECM.No spark output at the coilsNo fuel injector pulses. Any ideas for correcting the “No Communications” problem would be greatly appreciated. According to Chrysler, the Front Control Module (FCM) acts as global communicator for all of the other modules. Does anyone know of a way to bench test the FCM? Someone else suggested trying another ECM, in case this one is bad. Sure, it could be bad. I’m not sure if it was working before the SKIM delete was performed or maybe it went bad BECAUSE that was performed. I thought about plugging this ECM into another car, just to see if it would communicate, but according to Chrysler, doing that would reactivate the SKIM system, thus negating the $125 SKIM delete that I’ve already paid for.
Hi @HemiBill, Don’t know the answer but here’s a link to the Chrysler 300C 2004-2010 Complete Service Repair Manual + Wiring Diagrams. Click on the Electronic Control Modules link to get to the relevant section of the manual. Select fullscreen mode to make it easier to view and if it is useful, there is a download link in the top right corner of the page, so that you can access it easier later on. ON p.8E-11 (or p.11/304 top left corner), it details how to perform diagnostics on the FCM. I think ;-) This is not in my area of expertise but hopefully you should understand it.
To fix my no communications issue, I connected the 2 pairs of CAN wires at the Front Control Module. I don’t know where that second pair of wires is supposed to be connected, but jumping it to the first pair of CAN wires made the system communicate. But the engine still would not try to start. Fast forward to this weekend and I made some more progress . I had previously not connected the ECM C1 pin 30 (yellow wire, “FUSED IGNITION SWITCH OUTPUT (START)”) because I was not using the ECM to trigger the starter relay. Apparently the ECM needs this input to know when the engine is being started (as opposed to just providing fuel & spark based on cam & crank signal inputs). Now it starts (mostly) and I’ve got some drive-ability issues to sort out.
