Turbo Diesel Registry
Issue link: http://read.uberflip.com/i/594528
22 www.turbodieselregister.com TDR 90 TRANSMISSION JUMPS OUT OF GEAR The automatic transmission in my '10 Turbo Diesel jumps out of fifth gear or sixth gear with the slightest throttle increase. There is a diagnostic trouble code (DTC) P0735 present. The transmission fluid is clean. What is wrong? SRay DTC P0735 = Gear Ratio Error in 5th. The transmission is slipping in fifth gear and sixth gear and it is likely due to a burned overdrive clutch. You will need to remove the transmission, disassemble it at least partway, and inspect/replace the overdrive clutch pack. TransEngineer, Grass Lake, MI TRANSMISSION QUIT WORKING The 68RFE automatic transmission in my '08 Turbo Diesel 2500 has started to shift erratically between fifth and sixth gear. It would hunt for a gear and feel like it was slipping a little and then would go into limp home mode. It would then start in first gear and shift directly to fourth gear. It recorded diagnostic trouble code (DTC) P0868 = Low Line Pressure. Suspecting a cracked or loose spin- on transmission filter, I had the fluid changed, the filter replaced, and the code cleared. Unfortunately, it did not fix the problem. I discovered that if I manually selected the fourth gear position which prevented the transmission from attempting to shift to fifth or sixth gear, it worked fine. It never recorded another DTC. When the transmission shop was on a test drive with the scanner plugged in, the transmission quit pulling completely. The truck would not go forward or backward and it had to be towed back to the shop. Input from TDR members please. TSandner, Gurley, AL When the transmission shop was on a test drive with the scanner plugged in, the transmission quit pulling completely. Have the shop reconnect their scanner and check the line pressure and the desired line pressure with the transmission in Park at around 1,200rpm. The line pressure should match desired line pressure within a couple of psi. If not, then it is likely either a loose, dislodged, cracked, split open, etc. filter or, if filters are okay, a stuck main regulator valve in the pump, which requires removing the transmission to inspect and repair. If line pressure is okay, then check engine speed, turbine speed, and output speed, while idling at a stop with the transmission shifted in drive or reverse. If all three are greater than zero, the problem is not in the transmission. Either the transfer case is in neutral, or rear driveshaft or rear axle has failed. If the turbine speed is greater than zero, but output speed is zero, the transmission is slipping which requires removing the transmission, disassembly to inspect the clutches, and repair as needed. If turbine speed and output speed are both zero, then remove the transmission and check for a broken input shaft, failed torque converter, broken flex-plate, or missing torque converter bolts. TransEngineer, Grass Lake, MI When the shop removed the transmission pan, they found the pressure had built up to the point where it blew the spin-on filter off at the threads, stripping the threads in the process. There was also significant clutch material in the pan. I guess that when the filter blew it let the clutches slip and wear off the material. With the amount of material in the pan, I would no longer have confidence in the transmission, so they replaced the transmission with a Jasper rebuilt unit. The good part is the 3yr/100,000mi warranty, the bad part is the expense just under a $4,000. I suspect that the main regulator valve TransEngineer suggested was a high probability. I'm sure if we could have gone that far with troubleshooting it would have been a much less expensive fix. TSandner, Gurley, AL The spin-on filter is not subject to line pressure. It is only subject to the pressure in the cooler return line. The filter was the problem. It sounds like either it was tightened too much when originally installed, it was not tightened enough causing it to loosen and fall off, or you got your torque converter fluid so hot that even after passing through the cooler, it was hot enough to weaken or melt the plastic snout. TransEngineer, Grass Lake, MI Engine Coverage of the '07.5 to '15 Model Trucks. Web Site Correspondence Edited by Bill Stockard.