I have a 2010 Toyota Corolla S automatic transmission with over 183,000 Miles. Transmission code P0974 (shift solenoid "A" control circuit high ) one mechanic told me the transmission has to be replaced. Haven't noticed any shifting issues.
replace the bad solenoid,
No. You should avoid entering the transmission if you don't need to.
The transmission should be diagnosed properly with the correct tools to find out if the problem lies in the wiring, TCM etc first.
https://www.youtube.com/watch?v=Sr7woeza8to
Tell the "one mechanic" to shove it and find someone competent.
https://www.autocodes.com/p0974_toyota.html
Drop the pan, replace the bad solenoid, replace the pan - done.
Hey. I had that same code once or twice or maybe for a month. I wanna say that has to do w the solenoid pack or similar. And not getting a good signal to the solenoid that controls the fluid pressures. I think. Sorry been over a year since dealing w it. I didnt replace anything in my 4r100 tranny when everyone told me it was doomed and to get a new one. I thought nah I got this. Came to find out mine had over 300k miles on it and was original equipment. That made me s my pants some. What I did was drop the pan. Cleaned everything inside that darn thing. Took the solenoid pack out. I cleaned off all the small bits of sludge or grime on the metal contacts. Cleaned all of it well. Then started cleaning every crevice and the dumb ball pressure holes things. Ball check valves. I cleaned any springs I came across as well. I basically laid under my truck for hours just wiping the gunk and thick fluid that accumulated in pockets. I then flushed the old fluid out by disconnecting the tranny return line and attached a hose that went to a Home Depot bucket instead of it returning to the transmission. Once I had the pan and the underside of the tranny that to me looks like one of those brain corals and then also cleaned the solenoid pack well. And made sure to put in a new filter and the magnet. Let the atv gasket silicone sit for the recommended 24 hours. And I adjusted the torque after the hour or so of whatever the atv sealant said to. I then bought high quality tranny fluid from red line the high temp stuff. And filled the transmission up. I filled it more then what the dip stick says to. W the return line in a Home Depot bucket and the Trannny filled not much past the full mark I started the truck. And what I had read was to put the transmission into each gear at least once before your done flushing to get any old fluid out of whatever crevice they in in the tranny I turned the truck off after 10sec. Maybe sooner. Then refilled the transmission fluid for the second time w the higher quality fluid or whatever that fits the specs for your tranny. And repeat. I think I did a different gear each time I refilled it. The vehicle I have fully filled w fluid is a lot. I forget. So it took me at least five or so times to flush what was in the torque converter, lines and radiator so i start the truck and flush and count the second and shift into a different gear. Turn it off. Refill. And continue until you see new fluid coming out the hose that you have going to that Home Depot bucket. Don't leave your vehicle on for very long. I may have just had it on for the gear shift. However many seconds that is. You don't want to go dry in the pan totally. You'll damage the tranny. It seems complicated but I had to do it for my situation. You might be able to get away w changing the filter and fluid. And wiping everything down real well, but the lines. And the torque converter and cooling radiator all have old fluid in it. And any debris that's accumulated in your transmission fluid. So you'll prob dirty up the solenoid again causing a less then needed electrical connection. Just make sure to put the right fluid cuz even a small difference will eventually brick your tranny. Or cause damage.
