48RE Trans Issue

S

Streetstock89

New member
Hello everyone new to this site. I have a 2007 Dodge Ram 2500 SLT with the 5.9 and having issue with my 48RE. Same issue as posted by D45 under the same title only I am getting a check engine light. The code is P8660 (Low Pressure). I checked fluid level - good, changed the governor solenoid and pressure sensor twice no luck. First time worked for 7 months the second time all of 15 minutes. The check engine light with the low pressure code is making me wonder if my problem might be an internal one and not the solenoid or pressure sensor. I have not replaced the lock up harness though. And am wondering if it is the upgraded solenoid that is causing the problem and if I replaced it with the original one that came with the truck if that would solve this problem as well.

Symptoms: Check engine light Code P8660

Truck is in limp mode after fluid warms up.
Took to a shop and they verified that when the fluid warms up voltage pegs out at 5 volts and stays there.
Have guys saying that it is the ECU
Have guys saying it is the valve body
Have guys saying rebuild the trans
I can get the truck to work fine if I shift truck into neutral then manually put it into first and work my way up the gears.


Do not want to just throw parts at it as the ECU is 699, can get a valve body for 185.00 and a rebuild for 1400.00 but I have to pull the trans and bring it to him then put it back in.
Hate to do that and find out it is the ECU and don't want to go the ECU route if it is the Trans. Only have money for one or the other not both.

then I came across D45 post and if that is the problem that would save me big bucks.

any ideas or suggestions?
 
Check main line pressure at the transmission. Plenty of information here or google on the transmission ports and locations. Make sure you have at pressure gauge good to 100 psi minimum. Main line pressure port is behind the front servo port. If you have a stock VB you should see 55 psi give or take a bit. It should be 90 psi at WOT. If you have a modded VB then call the builder of the VB.

If you are not seeing that and as you mentioned; solenoid and transducer have been changed. You may have a bad VB. The lube pressure regulator valve may be sticking. This happens mostly from the bore wearing which I have seen before.

Check this first before you spend any more money.
 
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raychem said:
Check main line pressure at the transmission. Plenty of information here or google on the transmission ports and locations. Make sure you have at pressure gauge good to 100 psi minimum. Main line pressure port is behind the front servo port. If you have a stock VB you should see 55 psi give or take a bit. It should be 90 psi at WOT. If you have a modded VB then call the builder of the VB.

If you are not seeing that and as you mentioned; solenoid and transducer have been changed. You may have a bad VB. The lube pressure regulator valve may be sticking. This happens mostly from the bore wearing which I have seen before.

Check this first before you spend any more money.
Click to expand...
Thanks I shall do that over the holidays.

Sent from my XT1650 using Tapatalk
 
Pressures are good and I found out that the P0868 Code is high voltage which is the indications I was getting. Looks like an electrical issue somewhere. P0868 is low pressure for the 6.7 only. The 5.9 the code is high voltage.
 
Unplug the connector on the outside of the case to see if there is transmission fluid in it. The VB harness connectors are prone to cracking and leaking up through the pins causing all “shorts” of issues. It Put mine into limp mode and it would do exactly what you described above. Use to be like a 50/50 fail rate new out of the box a few years back I guess on the VB harnesses.
 
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