Code p0758, solenoid location

This could be a couple of things so we need to run through the testing that is attached below to find out for sure.

The shift solenoid is on the valve body in the transmission so if that is the issue then I attached the process to replace this as well.

However, this could also be a wiring issue or ECM so we need to run through the testing to find out for sure what the issue is.

Let's run through this material and let me know if you have questions. Thanks

Were you able to find the cause? I’ve tested the wiring, replaced the solenoid, and replaced the computer. I can’t for the life of me figure out why I have this code and why the transmission is having a hard time with shifting

Yep, you can get this code if the fluid pressure is not correct, this can happen because something inside the transmission has let go. Is the transmission fluid clean and full?

The transmission is filled perfectly to the hot line when hot and the fluid is clean. I dropped the pan when I changed the solenoid, so I also replaced the filter. What else could cause the p0758? I’m not convinced that something mechanically wrong could be the issue since it’s an electrical fault code…

When you removed the solenoid did you test it with 12 volts and hear a click? Also, the solenoid "B" is the one that has the blu/blk wire going to it, can you confirm?

P0758 - Shift Solenoid B Electrical (Shift Solenoid 2)

Here is a guide to help check the wiring to the PCM.

https://www.2carpros.com/articles/how-to-check-wiring

Also, if you have a bidirectional scanner, you should be able to command the solenoid on and hear it click. Here are the wiring diagrams so you can check it out. Also, you might want to unplug the cruise control module as well in case it is blocking the signal. Check out the images (below). Please let us know what happens.

Ken, I greatly appreciate your help. When I removed the original solenoid, I tested it and it was perfectly fine (it clicked when 12 volts were applied and its resistance checked out according to my repair manual). I only swapped it out because I already had a new one and wanted to make absolutely sure that the solenoid wasn’t the culprit. I don’t remember if it was a blue and black wire going to the solenoid, but solenoid A and B have different brackets, so I know I ordered the right part and replaced the right solenoid.

I do not have a bidirectional scanner. Couldn’t I just apply 12v to the solenoid connector (only the B pin) outside the transmission and listen for a click? I don’t think the solenoid is the issue because sometimes my car shifts from 2-3 perfectly fine. It is very intermittent when it decides to slip down to 2nd or not go into 3rd gear at all. Usually only happens when accelerating.

I did try unplugging the cruise control module yesterday since I saw that it was part of the wiring diagram and I cleared the CEL. It did not fix the issue unfortunately. The cruise control module is under the hood, correct? On the left side of the battery?

It says the cruise control module is on the left side of the dash. Check the image below.

I just tried unplugging that as well - no dice. Code came back after 10 minutes of driving:(

Okay, you are back testing the wire, like I say the transmission can have an issue internally that causes this code. It is a circuit code which can be high or low which would be a fluid pressure error causing the currant error.

I’ve already tried testing all of the wiring… nothing was out of the ordinary. I’m about to give up on this car and sell it.

That leaves the transmission or the PCM, sorry.

I already tried replacing the PCM (ECM). The issue persisted. It can't be a mechanical issue, can it? It's an electrical code, so doesn't the issue need to be electrical? Could a clogged valve body cause this code?

I know the solenoid works sometimes, because there are times when the transmission shifts perfectly fine. I think it only has issues once the transmission gets hot, which is weird. does it make sense to tap the prong of the solenoid B connector with the 12V battery to listen for a click? Since the issue is intermittent, this test might be useless anyway.

Sure you can give it a try, it sounds like you have tried everything except the transmission. A hydraulic issue will cause an electrical code due to the resistance change because of the lack of pressure. I mechanical issue can come and go at times. Try probing the wire and listen for the click and if you hear one the transmission is bad.

Are you sure it could be a bad transmission? According to my repair manual, it says that the issue can only be in the wiring, solenoid, or ECM. You’re saying that transmission pressure affects the solenoid resistance? According to a quick google search I did, the resistance should remain constant across the solenoid regardless of fluid pressure.

Obviously, I’m not as experienced as you so pardon my skepticism- you can understand that I don’t want to believe that my transmission is completely toast :(

Good call, try activating the solenoid by giving it 12 volts to see if you can hear it. You tested the wiring, replace the PCM and shift solenoid so there is not much left, unless you changed the wrong part out, do remember the wiring color?

I do not remember the wiring color, but I’m 100% sure that I changed the right one. They have different brackets, and I double checked a million times before installing it. I hear a click when testing both solenoids A and B. This truly is a mystery to me but the issue is very intermittent. So, it’s possible the issue isn’t presenting itself when the car is cold.