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FIXED BAD ECM ,Suzuki experts 2010 Suzuki equator 4.0 a crank no start
I have a crank no start issue on this Suzuki equator I have literally tested and have gone through almost everything 1st of all snapon modis edge will not connect to the ecm I can talk to the TCM and BCM
Computer is not reading that Ignition is on
Codes I receive are u1000 CAN Lost communication
Test I have done is check at the ECM CAN low /high I am getting a good wave form on the scope it is sending and receiving
Ran the same test on the TCM once again sending and receiving
Checked crank and Cam position sensors also I received a wave form So I know it's getting power from the ECM
Vehicle still not starting ECM is receiving switched Ignition 12 V so is TCM I have checked all the ground wires I Could find what else should I do next??
There are more computer powers than just ignition on. Do you have a diagram for this vehicle to check all power and ground? Are you load testing them or just continuity/volt testing? The signal on the can network doesn't mean the ECM is sending anything that just means that a module is sending information .do the high and low mirror each other? Did you check the resistance of the network to verify 60ohms?
No diagram , I load tested power on the ecm , ground I did was under 100 mv, I used one channel at a time good known ground and yellow scope wire to can high and tested low separately I can test both at the same time to see if they mirror each other i didn’t know that had to mirror one another , and you want me to ohm low to high can at ecm?
So guys any tips on how to confirm that my ECM is the culprit remember there is no communication to it I can communicate to the other computers just fine
That doesn't look like a good can signal to me? Others may have a different opinion I would guess we're dealing with a shorted 5v or a bad power or ground. Start by checking a 5v ref koeo at whatever sensor is easier to get too (there's a link to Bbb industries diagrams in the service information tab at the top of the forum .
As your looking at voltage you will see the same signal anywhere you connect your leads on the can network (this will not tell you if any 1 module is talking) your signal is all jacked up saying that a module is messing up signal I would bet if you unplug the ecm the signal will look better but we don't need to do that since that's the only module not communicating . the next step is to check for a shorted 5v ref pulling the computer down or missing power or high resistance in the ground circuit.
Aww Yes that makes sense this whole can network system is new to me I hear what your saying by disconnecting other modules I can isolate which one is causing the bad communication wave form, I checked my powers and grounds going to the ECM I will recheck again though , How would I find out if a 5 V reference is pulling my computer down by not unplugging every single sensor on the engine.
I isolated the CAN communication lines at the computer and retested got no readings at all didn't even get voltage on my pink and blue can wires, At this point I'm thinking the ECM is pulling itself down
I isolated the ECM by cutting the pink and blue can wires with everything plugged in and connected Tested communication wires coming out of the ECM (no signal)
The graph that I showed earlier was with everything intact, And communication wires running to all the other modules now I know I was reading the other modules
This is my new wave form with communication wires cut and tested at ECM looks way better Both voltages also add up to 5 V
2nd picture I am supposed to be getting 12 V at 119 And 120 I only get 12 V when harness is plugged into ECM coming out 119,120 when it is unplugged I am getting no voltage but with no diagram I'm not sure if 12v is supposed to come out or go into ecm might be normal
I am getting voltage on Switch Ignition voltage 109 and ecm memory 121 unplugged from ecm
Just a quick note, when your checking your computer grounds and you should be on the battery negative post, you said you went from a "known good ground" just a thought
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