Okay, you got 2.5volts on the E and F pins of the data link connector? And you are still getting the same codes, with the P0606 showing up first? I'm just going over your case folder again. So, it seems that under a heavy load or wide-open throttle the fault occurs. Under 2500rpm it seems fine.
Something to note, that if it's a wide open throttle run where this is occurring, is that the PCM will go back into open loop during a throttle input like that, it does this because in that situation you need all the power you can get (for example if you're trying to get out of the way of oncoming traffic or a Semi) the PCM will ignore the Oxygen sensors and other input sensors, not worrying about emissions at that point, but go back into closed loop when you return to normal lower rpm driving. I'm wondering if that has something to do with this. I am just going to look through some more service info and let me know if you're getting any other codes now, or any other odd things you notice.
Ok when we look at the Flow Chart here for the canbus diagnostics, out of the 8 pages, I only get to page 2. Where its states on step 2, Are any DTCs other than the following displayed? And there is, the P0606. So, I think that is going to possibly be the source of our issue here.
On the OEM diagrams PCM pin 1AY is the Drive by wire Relay control pin. And hopefully these diagrams are correct. So let me pull up these PCM diagrams and see if there's anything that could link these issues together, maybe there is a short somewhere in the throttle control motors or relay circuit that is spiking the power feed and knocking out the comms or sending a voltage spike into the PCM or other modules.
Also, can you look and tell me if your vehicle is California emissions or Federal Emissions? It will be on the tag under the hood, or in the driver's door frame.
In the meantime, I want you to pull the Ignition Coils and inspect them one by one, look very closely at the coils boot that goes down to the spark plug for any carbon tracking or marks on them, take pictures of each coil if you don't mind. Check the spark plugs as well for any carbon tracking on the sides where the boot attaches on. Also look for any cracks in the plugs. Ignition coil spikes can jump into the Ground side of the electrical system and cause all kinds of strange issues. And at a higher rpm the coils will be stressed more with a high Kv voltage. There could be a coil spiking into the ground causing issues like this. Normally I would use an oscilloscope to monitor all the ignition coils for any high voltage spikes but in this case, you will have to do a close inspection of them. If there are any cracks in any of the spark plugs, they will be very small, so look closely. Take pictures of the plugs too if you don't mind. So, we can get to the bottom of this somehow. And we'll go from there.
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Sunday, June 11th, 2023 AT 8:41 AM