2007 5.7 HEMI Ram 1500 4wd
Hello, I am coming to this site because I have had zero luck on another site. My 2007 Ram 1500 5.7 has had a weird issue..
160k... 545rfe trans
So I will give a chronological timeline of how a drive will go..
Park to drive 2.5 sec delay till engage..
drives fine, upshifts very smooth and quick
once 45 mph hits, OD seems to engage and all is good. The problem is when I accelerate from that point, or even if I slow down ANY decent acceleration will result in a harsh downshift (more throttle more flare)
IF I turn overdrive off it downshifts totally fine.
SO I hooked my scanner up to it and noticed that there was erratic behavior with the UD pressure switch and LR pressure switch. LR would turn on and off a few times when Park to Drive was selected. Once engaged, switch was normal.
Same thing when the flare would happen upon downshift from OD. When OD was disabled, all was normal.
I changed the solenoid pack and both filters with OEM dealer parts, upshifts seemed to improve but nothing else changed.
Scanner also shows ECT sensor WAYYYY high .. so the coolant temp was 240 degrees on a 60 degree day before starting overnight. When driving, the first sensor reading is over 600 degrees Coolant Temp! The second display (gauge) is reading 201 degrees usually. The gauge shows normal reading and the second sensor reading was normal as well. I changed the ECT twice and it still is showing the same issue. Seems to be a short in the two wires, I understand that colder equals more resistance and hotter will decrease resistance. It seems that the wiring is shorted and the PCM thinks there is no resistance period. Would this affect the shifting, schematic shows that ECT is in sync with OD operation.
Also, the trans will shift hard from 3rd to 1st when slowing down around 10 mph or so.. that is when underdrive switches also underdrive is erratic when the downshift from overdrive occurred.. on off on off.. when it finally engages, behavior stops.
When I dropped the pan, magnet had almost no clutch material on it, no shavings and no metal chunks. Fluid was still red and smelled like regualr trans fluid.
I am thinking there is an electrical issue that is causing OD and UD to interfere or stick.
Please help, I have tried trans shops and of course they said Rebuild without even looking at it and that is all good and I know it will fix it (maybe) but lets be honest, I am a firm believer of DIY and the most satisfying thing is when you fix the issue without doing a blanket rebuild to fix a small issue.
so ultimately, all upshift is fine, downshift is hard and delays from OD only, OD off equals no problem.
SIDE NOTES, the low oil pressure code is showing as well, been that way with two new sensors installed. Idle PSI is 30 or so and acceleration usually is over 50. no knocks or noise. Been that way for a while. Seems to be weird electrical issues throughout the vehicle, I have inspected the harness and did not see any smashed or grounded wires yet. Maybe a bad ground?? I tried jumping ground and it did not do anything.
Could the PCM be faulty or needing flashed? Anyone ever see this issue?
Please Help!!!! and Thank you in advance!
I know that I can check ground and continuity for the ECT I just have not had time yet.. Ill get there!
Last edited by ruggeri5054; 09-23-2018 at 07:31 PM.