96bulldogpower Posted 7 hours ago Share Posted 7 hours ago Hey guys I have an issue with our main problem child again. Truck is a 12’ granite mp7. A bit of history, we got the truck with a burned ecm when we bought it, we replaced the ecm with a used one and it ran for a while, we started having issues with emissions components so we had it deleted about 3 months ago. Then truck ran great for 2 months then the ecm failed again this time it still started but only ran on three cylinders. We replaced the ecm yet again with a used one and had it deleted again and the truck ran great for 2 weeks. Today, we started the truck in the morning and it ran for 10 seconds then shut off, now if you try to start it only the dash lights up like usual but the engine doesn’t crank or start. I did the preliminary things like checking fuses and battery connections (new batteries three days ago), but nothing seems out of order. I’m having someone bring me my laptop later today to hook up and see what’s going on, but I’m already suspecting bad ecm again. Do you guys have any insight? What can be causing this truck to repeatedly burn ecm’s? Any tips on dealing with the no start no crank if it isn’t the ecm? It did start initially for 10 seconds before going dead. Quote Link to comment https://www.bigmacktrucks.com/topic/76364-another-mp7-no-crank-no-start-with-history-of-burned-ecm%E2%80%99s/ Share on other sites More sharing options...
96bulldogpower Posted 6 hours ago Author Share Posted 6 hours ago Well guys I got it hooked up and it’s not looking good. No hours on the hour meter and it has communication codes. This is classic of yet another burned ecm. Does anyone know why this truck keeps burning out ECM’s? ill do some more diagnostic on it later today when I have time just to rule out other variables, but im pretty certain its got a bad module. Quote Link to comment https://www.bigmacktrucks.com/topic/76364-another-mp7-no-crank-no-start-with-history-of-burned-ecm%E2%80%99s/#findComment-590363 Share on other sites More sharing options...
880joe Posted 4 hours ago Share Posted 4 hours ago Any chance you might have antifreeze or oil wicking into the ECM? That was an issue on the E7'S some times 1 Quote Link to comment https://www.bigmacktrucks.com/topic/76364-another-mp7-no-crank-no-start-with-history-of-burned-ecm%E2%80%99s/#findComment-590378 Share on other sites More sharing options...
96bulldogpower Posted 3 hours ago Author Share Posted 3 hours ago 4 minutes ago, 880joe said: Any chance you might have antifreeze or oil wicking into the ECM? That was an issue on the E7'S some times Ecm plugs are completely dry, I did injectors on this truck not that long ago and I saw oil in the connectors for each injector so I figured it was on borrowed time for a new engine harness, but no there’s no oil or coolant that has made it yet to the ecm connectors. Quote Link to comment https://www.bigmacktrucks.com/topic/76364-another-mp7-no-crank-no-start-with-history-of-burned-ecm%E2%80%99s/#findComment-590379 Share on other sites More sharing options...
Geoff Weeks Posted 3 hours ago Share Posted 3 hours ago repeated bad ECM's with comm codes would have me looking at the wiring harness also. My guess is something is cross shorting and frying communication. Going to be hard to find. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/76364-another-mp7-no-crank-no-start-with-history-of-burned-ecm%E2%80%99s/#findComment-590380 Share on other sites More sharing options...
Joey Mack Posted 3 hours ago Share Posted 3 hours ago I guess he needs to unplug the E.C.U.'s and check for continuity on every pin to every other pin in each plug end. when he finds continuity, then he finds the 'short' This is tedious, but so is paying thousands to buy ECU's only to cook them. Im seein the Vehicle module and I think the injection control module are faulting. What is the ICM, again, I forgot. 2 Quote Link to comment https://www.bigmacktrucks.com/topic/76364-another-mp7-no-crank-no-start-with-history-of-burned-ecm%E2%80%99s/#findComment-590381 Share on other sites More sharing options...
fjh Posted 2 hours ago Share Posted 2 hours ago It’s not uncommon for bad wiring under the valve cover will shut down cylinders and werid stuff goes on! A place to look! just sayin 2 Quote Link to comment https://www.bigmacktrucks.com/topic/76364-another-mp7-no-crank-no-start-with-history-of-burned-ecm%E2%80%99s/#findComment-590384 Share on other sites More sharing options...
96bulldogpower Posted 1 hour ago Author Share Posted 1 hour ago I agree that it could be wiring related, I spent some more time with the truck trying to figure out what’s going on. The engine ecm is definitely offline, it won’t communicate with the laptop. Power and ground leading up to it seem fine from what I could test with what tools I had available to me. As much as I hate to “parts cannon” a truck, I think I’m going to try replacing the engine harness. It still needs an ecm though from what I can tell. I already took the ecm off, I’ll have it tested and repaired tomorrow if all goes well. Could someone please get the the correct part number for the engine harness for the truck? 2012 GU713 MP7 VIN: 1M2AX04C5CM011802 Quote Link to comment https://www.bigmacktrucks.com/topic/76364-another-mp7-no-crank-no-start-with-history-of-burned-ecm%E2%80%99s/#findComment-590388 Share on other sites More sharing options...
Geoff Weeks Posted 44 minutes ago Share Posted 44 minutes ago (edited) This is a little out of my experience, however I know someone who posts on a different board, He repairs "lightening strike" vehicles. One thing I picked up from him, that one bad module can pull the whole Canbus down giving the impression that everything is "dead". Once the one the one thing that is killing communication on the bus is disconnected the rest can come back to life. This requires locating where they are tied to the canbus wiring and removing one by one, until the bad one is found, re connecting one by one to make sure you don't have more than one. He also says to check the resistance between the hi and lo buss wires and look for a set resistance (150 ohm?) I'm not sure about the resistance I could check with him if you get that far. Higher is an open somewhere and lower is something on the buss is shorted. Edited 43 minutes ago by Geoff Weeks Quote Link to comment https://www.bigmacktrucks.com/topic/76364-another-mp7-no-crank-no-start-with-history-of-burned-ecm%E2%80%99s/#findComment-590392 Share on other sites More sharing options...
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