any updates? Iím having the same problem with my 08 2.3L with same engine code. Iíve replaced all solenoids, changed fluid and it will randomly act up. I also had my TCM repaired. Today I removed the input speed sensor in attempt to test sensorís resistance. I got 29.2 from pin 1 and 2 and 7.9 from #1 and #3. I still have to check the wiring harness but not sure exactly how to test the large connector that plugs into the TCM. Any advice?
Posting the 2 PM messages I sent you so others can see my responses and get helped or chime in and add to or correct something I've said:
I assume you changed the solenoid pack in the pan and not the one on the side. Normally the issue with P0753 is the TCM, solenoid or wiring/connector.
If you changed the solenoid and still have an issue, then it is most likely something else. Looking on Mitchell prodemand at work, there are more fixes associated with the TCM than the solenoid. That said, it could be an intermittent electrical circuit issue with the wiring or the 3 related connection points of that circuit. I would verify that they are good. If they are good then it sounds like a TCM issue. I would definitely rule the circuit issue out first as $450 is a big price to throw parts at it.
As for the speed sensors, they wouldn't cause this specific issue. If they were bad then you would have a more broad symptom base as they effect the whole transmission and shouldn't cause a specific solenoid cause.
The only other thing not mentioned in the service manual is the possibility of a hydraulic issue in the valve body solenoid block that is intermittently not allowing proper ATF flow when the solenoid is energized (sticking valve, debris, etc...). Not usually common though. Just throwing it out as a possibility.
You might be able to find some youtube videos that demonstrate how to check the circuits and connectors and may have examples of what to look for.
The short of it: Most connector inspections are generally visual. Check for bent or deformed or corroded male and female pins and terminals. Make sure the terminals are tight enough to actually maintain contact on the inserted pins. If not, vibration and moving of harnesses under engine torque can cause loose connections.
To actually check the circuit, you would unplug the connectors at the TCM and transmission and check for continuity to ground and power to see if there is any kind of short to either. To check the circuit itself for resistance, I usually use a brake light bulb connected at one end of the circuit and a ground and apply battery voltage to the other end of the circuit with a jumper to the battery. This will complete the circuit and should light the bulb normally. Any resistance will cause a dim or no light based on the amount of resistance. I do this because a circuit that has no resistance on the meter may still not be able to carry a real world load. This is because a meter sends a vary small voltage through it. Most of the time it is a fair assessment, but I have been burned by it in the past therefore I like to verify with a real bulb. Hope this makes sense.
Also, there is no way to test a TCM or any module directly with the ohm part of the meter as that will fry it. You can check it with a the voltage part:
With the vehicle assembled normally, insert a backprobe into the transmission connector circuit for solenoid A. Have meter on DC volts and connect the positive lead to the probe and the negative lead to ground. Drive the vehicle and you should see 12 volts on the meter when the TCM energizes the solenoid. Driving like this when it acts up will tell you if the ECU is turning on the solenoid like it is supposed to. If it is and the circuit is good, then you should be OK with the TCM and it is probably a hydraulic issue. At this point though, you would want to pull the pan first and verify that it isn't the internal wiring between the trans connector and solenoid plug.
Hope this all makes sense.