Can't connect to ECM - Chevy and GMC Duramax Diesel Forum
11-16 LML Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

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post #1 of 5 (permalink) Old 05-25-2018, 09:19 AM Thread Starter
Join Date: May 2018
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Can't connect to ECM

ECM just died?
Hey guys. I flashed my brothers truck about two months ago with a tune from Motor Ops. Truck has been running good until Friday night. He was driving pulling a trailer and the truck just died on him. He was able to coast to the side of the road. We checked all the ecm fuses and they are all good.. The dash is currently saying "Service trailer brakes, service stabilitrak, parking sensors blocked". I can no longer communicate with the EMC. When i use EFI live I can see the A50 TCM but the ecm box comes up blank like it isn't there. Seems odd that the truck just shut off while driving and now won't restart. Tried jumping it incase it was the batteries with no luck. The truck wont even try to crank which i believe is do to the ecm being dead. So we purchased a used ECM from SoCal hoping that was the issue. Installed it and can't flash a tune. EFI live doesn't even show the ECM is there. However the TCM still shows up. Kind of at a loss with it. We will start tracing wiring but was hoping for some help on the issue. Is it possible to TCM took a dump and is making the ECM not connect even though I can still communicate with the TCM. Thanks for any help.
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post #2 of 5 (permalink) Old 05-26-2018, 12:16 AM
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Check the wiring harness, mine rubbed through and took out the ECM. Mine rubbed like 6 wires through and had wires showing on a few more right behind the A/C compressor bracket.
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post #3 of 5 (permalink) Old 05-26-2018, 12:18 AM
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There are a few other spots to check too that others have found bare wires.
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post #4 of 5 (permalink) Old 01-13-2020, 06:17 AM
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Join Date: Dec 2018
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Just wondering if the issue was resolved. I just replaced my ecm. And know I cant figure out how to load tunes
post #5 of 5 (permalink) Old 01-13-2020, 12:13 PM
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Join Date: Aug 2009
Location: Berryton, KS
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When you first turn your key to on, there are many lights on your dash that will light up momentarily, one of them being the CEL (check engine light), and that should go out after the truck starts. If you CEL lignt isn't on at key-on, it means that your truck has lost communication with the ECM. If you attach a code reader to your DLC (data link connector), it won't power up or read any computers. This may be because the cigarette lighter fuse has blown, or other shorts to ground in the circuit. If you can't communicate with the ECM, you can't load tunes.

Ron Nielson
2008 Silverado LT, CCLB, Edge Insight CTS
2009 Arctic Fox 29-5T, Silver Fox Edition, Onan 3600 LPG generator
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