48re lockup troubleshooting

M

megastang

New member
The other day I got on the highway and after was already up to speed I went to accelerate and noticed that RPM increased before any speed increase. There was a Code 1740 present. I replaced the OD and TCC solenoids, No change. I decided to do a little more testing which confirmed my suspicion that it was the TCC. I found a couple of really good articles (links at the bottom) which led me to drill my cooler line check valve, no change, then to bypass the coolers all together, no change.

I have an ATSG book but the troubleshooting it has focuses on the gov pressure issues. I checked line pressure at idle, it is 90 PSI which is high according to the ATSG book. This trans had been gone through 8 or so years ago so I'm guessing line pressure was adjusted at that time. I don't see anyplace to check TCC pressure which would be the next thing I would like to see. I would like to check everything possible before I pull the trans. I do see that the 48re has the TCC circuit connected to the forward clutch circuit which is interesting but not sure if that is of any significance.


740/1740 Codes and Chrysler Converter Flow - Transmission Digest

46-47RH/RE Cooler and Converter Flow - Transmission Digest
 
The only thing I can add is that you should see a jump in line pressure when the valve body attempts to apply the tcc. Mine jumps from 160 to 200 psi for instance.


Sent from my motorola one 5G using Tapatalk
 
I checked that after my post. Had to make a longer line to get the gauge into the cab. I turned overdrive off, at light throttle on level ground I notice a jump from 80 to 120 when the TCC is supposed to lock. I added some throttle and it dropped back to 80. I thought it was probably because of the light load situation that it was unlocking with just a little bit of throttle but now I'm wondering if that's the case. I'd like to do some more testing and see if it stays "locked" in different situations.
I have EFI live with a flashscan v2. I wanted to watch the TCC status but couldn't find it. I hope I was missing it somehow because it would be pretty silly not to be able to watch that.
 
I can see tcc status on my v2, you should be able to find it. I'm not much help on this one but brake pedal switch comes to mind as a possibility
 
Yep. Mine acted goofy for about two years before it went out completely and I realized it had been that the whole time.
 
Negative. The brake light switch. I had threads on here for my pot mod not working, TPS not working, etc. It was always rare and sporadic but never failed to happen on a big road trip.

I’ll keep it short and just say it started acting up consistently enough to test the switch last month. No problems since replacing the switch.

I’m not really educated on the 48’s, but wanted to echo thatguy69 In case it was a possibility.
 
You must log in or register to reply here.
Back
Top