Code P0780, Transmission whine?

JKAMPS

MEMBER
2003 HONDA CRV
2.4L
4 CYL
4WD
AUTOMATIC
216,000 MILES

We bought the car listed above used (EX) a couple of months ago. The mechanic we bought it from purchased it not running and replaced the transmission with a lower mileage unit; approximately 133,000 miles on it. My daughter drove it for a couple of months with no issue but then she was stranded when it stopped moving and the "D" was flashing. I noticed there was a pronounced whine coming from the transmission area that was not there when we bought it. I was able to limp it home, but it was having shifting issues. I pulled a P0780 code. I did the drain and filled it three times with Honda fluid and was not able to fix the problem. I checked the external solenoids and they all seemed to function when 12 volts were applied. I took it to a mechanic, and they diagnosed it with a transmission pump issue. They sent me a video of a pressure gauge bouncing all over the place and said the pump was cavitating. I limped it home and I am trying to decide whether to attempt to fix it or scrap it. My question is whether the internal solenoids could cause a pressure issue or if the transmission is gone? Thank you.

2 Replies

JKAMPS

MEMBER
2 POSTS

Another thing to note is that it is currently having trouble going into gear when it first started. It usually drops into reverse pretty easily but does not go into drive right away and then the D starts flashing again.

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Tuesday, September 13th, 2022 AT 12:36 PM

AL514

MECHANIC
4,688 POSTS

Hello, there is manufacture flow chart for this code, in which they have you replace the a/t clutch pressure control solenoid A, B, and C, then clear the memory, and test drive. If code comes back, they, have you replaced shift solenoids a, b, and c, clear the memory and test drive, if code returns, they want the transmission pulled and rebuilt the hydraulic system. So, in the long run, putting in another used transmission is obviously going to be a lot easier. These are decent vehicles if the engine is maintained. Oil changes and routine maintenance and they can go to 300k. With line pressures jumping all over the place it can be the pump or the control solenoids, but it's not worth the time or cost trying to replace all those parts. If you can find a decent used transmission, it can be worth it. It's a matter of what you want to spend. The used vehicle market right now is very high, so it depends if you think the rest of the vehicle is worth putting a used tranny in. One of the first things I noticed with these vehicles at that mileage was upper camshaft bearing noises. It sounds exactly like a squealing belt. If you don't hear any upper end noises, then it might be okay. Also, adjusting the valves in these is extremely easy and should be done every 30,000 to 60,000 miles. But by the sounds of that transmission, it will need to be replaced,
I would also have the entire system scanned for codes, not just the PCM, to see if there's anything else that would need to be addresses, i.e. airbag codes, ABS codes, etc. Hope this helps somewhat.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

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Tuesday, September 13th, 2022 AT 4:38 PM