usf97j4x41
TYF Newbie
- Joined
- Jul 5, 2023
- Posts
- 3
- Reaction score
- 3
Hey folks... I have a 2011 Denali with about 188k miles on it. Last week I was out of town on vacation and when I left the car was running just fine. When I got back from vacation I went for a drive and noticed a delay in engagement between first and second gear. It's about a half second delay, causing some RPM drop, then second gear engages and everything else is normal/smooth. No issues with it popping out of gear, no grinding, etc. If I baby the hell out of it I can get it fairly smooth, but it seems to be an issue whether the car is hot or cold (although cold does seem a bit better).
I checked the fluid levels and they were fine. I swung by a shop on a Friday afternoon and dropped it off only to get the keys back that afternoon with a "your transmission is toast you need to rebuild it for 5k" - I asked what exactly was wrong with it and he said there was a "pressure code." He didn't charge me, which was a bit suspect and makes me think he was just out to sell a new trans. I had been checking for codes on my code reader at multiple points and I never saw any transmission-related codes.
Fast forward, took it home, dropped the pan... fluid perfectly clean and no metal shavings on the magnet. I dropped the valve body down and separated the TEHCM. I immediately noticed that 2 of the 4 laminate diaphragms were cracked. I went ahead and replaced all 4 with the Sonnax replacement parts. Ran low pressure air through all 4 and they seemed to hold. I checked resistance on the pressure switch and they all read within the proper range. However, I realize now I didn't take a read on both open and close for each, only a tone check for open/close, nor did I check the readings on the solenoids. Anyway, I cleaned it back up, re-installed it, put in a new trans filter and gasket, and took it for a ride. I swear it seemed better at first (perhaps wishful thinking) but by the time I got back to the house I noticed it was doing the same exact thing again. I reset the computer just in case but still no change.
It's also worth noting that I have a P0523 oil pressure sensor code that's throwing (showing 3 times in the reader for some reason). It's been on the fritz about a month/month and a half and I went to replace it the other day the sneaky way but screwed up and nicked the wire harness which means I need to pull the damn intake manifold to replace it. At this point I probably won't bother until I know what's up with the trans... that said, I am assuming the oil pressure sensor has nothing to do with the transmission issue, because the sensor has been out a while and the trans issue is new, but again, worth noting.
At this point part of me wants to pull the TEHCM again just to make sure the diaphragms and gaskets I put in didn't shift around somehow, and I still might, but I am pretty stumped as I literally SAW the broken ones, fixed them, and thus I assumed something should have improved. I should also probably recheck just to check the readings on the solenoids as well. I'm not really sure where to go from here short of pulling the trans out of the car and breaking it apart, which isn't that much of a nightmare but I just don't have the tools/room to do it. Is there anything else I can look into short of doing that? The fact it was fine before I left it sitting a week and then it came back with this issue strikes me as really weird but I guess it could be a fluke. In any event, if I need a full rebuild I am likely just going to scrap the car, or just drive it until I can't anymore, which sucks because I was REALLY hoping to hit that 200k mark.
Thanks for any info/help ya'll can provide!
WW
I checked the fluid levels and they were fine. I swung by a shop on a Friday afternoon and dropped it off only to get the keys back that afternoon with a "your transmission is toast you need to rebuild it for 5k" - I asked what exactly was wrong with it and he said there was a "pressure code." He didn't charge me, which was a bit suspect and makes me think he was just out to sell a new trans. I had been checking for codes on my code reader at multiple points and I never saw any transmission-related codes.
Fast forward, took it home, dropped the pan... fluid perfectly clean and no metal shavings on the magnet. I dropped the valve body down and separated the TEHCM. I immediately noticed that 2 of the 4 laminate diaphragms were cracked. I went ahead and replaced all 4 with the Sonnax replacement parts. Ran low pressure air through all 4 and they seemed to hold. I checked resistance on the pressure switch and they all read within the proper range. However, I realize now I didn't take a read on both open and close for each, only a tone check for open/close, nor did I check the readings on the solenoids. Anyway, I cleaned it back up, re-installed it, put in a new trans filter and gasket, and took it for a ride. I swear it seemed better at first (perhaps wishful thinking) but by the time I got back to the house I noticed it was doing the same exact thing again. I reset the computer just in case but still no change.
It's also worth noting that I have a P0523 oil pressure sensor code that's throwing (showing 3 times in the reader for some reason). It's been on the fritz about a month/month and a half and I went to replace it the other day the sneaky way but screwed up and nicked the wire harness which means I need to pull the damn intake manifold to replace it. At this point I probably won't bother until I know what's up with the trans... that said, I am assuming the oil pressure sensor has nothing to do with the transmission issue, because the sensor has been out a while and the trans issue is new, but again, worth noting.
At this point part of me wants to pull the TEHCM again just to make sure the diaphragms and gaskets I put in didn't shift around somehow, and I still might, but I am pretty stumped as I literally SAW the broken ones, fixed them, and thus I assumed something should have improved. I should also probably recheck just to check the readings on the solenoids as well. I'm not really sure where to go from here short of pulling the trans out of the car and breaking it apart, which isn't that much of a nightmare but I just don't have the tools/room to do it. Is there anything else I can look into short of doing that? The fact it was fine before I left it sitting a week and then it came back with this issue strikes me as really weird but I guess it could be a fluke. In any event, if I need a full rebuild I am likely just going to scrap the car, or just drive it until I can't anymore, which sucks because I was REALLY hoping to hit that 200k mark.
Thanks for any info/help ya'll can provide!
WW
