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transmission solenoid pack problems

36K views 75 replies 4 participants last post by  Frango100 
#1 ·
ok i a 2000 jeep grand cherokee 4.7 with the 45fre. i have recently had transmission troubles that lead to me having to change out the transmissionn solenoid pack and it worked great for a about a day and now it goes in and out of limp mode at random times. sometimes i start it and it will go fine and others just limp mode. i did use the white plug pack on replace ment and a new bracket that should work said it worked for 45fre or 545fre. i got my pack form quality transmission parts in tampa florida. it is a used one though it was going to be a refurb. so does anyone know what i should do?
 
#4 ·
The transmission system holds 13 qts in total, but when you lower the pan you will only get around 6 qts out of it, the rest is inside the torque converter and lines.
When the transmission goes into limp mode, you should have a "check engine" light with the P0700 general transmission code. You need to get the TCM scanned to know what failure it has stored.
Best is to check the fluid level with the transmission at operating temperature. A too low level can indeed give strange behaviour.
 
#5 ·
The transmission system holds 13 qts in total, but when you lower the pan you will only get around 6 qts out of it, the rest is inside the torque converter and lines.
When the transmission goes into limp mode, you should have a "check engine" light with the P0700 general transmission code. You need to get the TCM scanned to know what failure it has stored.
Best is to check the fluid level with the transmission at operating temperature. A too low level can indeed give strange behaviour.
Yea its not in limp mode any more but check light is on and when I tried getting it read last time it was just like this it didn't throw any codes. And I live on a pretty rough road and after hitting a lot of potholes it went into limp mode or after I was parked on a hill for awhile that's why I think it may be the fluid level.
 
#6 · (Edited)
Yeah, top off the fluid at the max level and try again. Let us know if it solved the problem, or otherwise we see where we go from there. Did you have any failure codes before, that made you decide to change the solenoid pack?
 
#10 · (Edited)
Did you fill the transmission already and it still goes into limp mode?
The P0750 code was indeed pointing towards the solenoid block, since this code is for the L/R solenoid (low/reverse). The P1786 is the pressure switch for the L/R clutch, which probably was caused by the failing L/R solenoid.
The P1768 is a " Transmission control relay off" code. This is a normal code when the TCM switches the transmission in limp mode. The TCM just removes the power to the relay.
If you still have the problem, then you should start with checking the fault codes again, before changing any more parts.
 
#13 ·
Just to rule out the Transmission Control relay to be the fault, you could swap it with the auto shutdown relay. Both are sitting in the PDC under the hood. Disadvantage is that if the relay IS the problem, that your engine will shutdown. So you should only try this as a test, knowing that the engine could shutt down at any moment.
 
#18 ·
The P0750 and P1768 you had before already, the P0755 and P1733 are new.
The P0755 is shift solenoid B malfunction and P1733 is 4C pressure switch sense circuit, indeed both have to do with the solenoid block.
But it seems that the solenoid block change didn´t do any good for the L/R solenoid (P0750). Eventhough the new (remanufactured) block can have a problem(s), it would be a coincidence that it has a problem with the same L/R solenoid.
The new problems could be from the new block. I would recheck the large connector on the block to be sure that its completely inserted and the lock lever is in its locking position.
Also remove the large connector on the TCM in the engine bay (the one with the bolt in the center) and check for moisture and/or corrosion on the pins. Use some electrical contact cleaner to clean the pins well and some shop air when available to blow it completely dry (check both sides, connector and receptacle).
I would also check the cable bundle as far as possible, also under the jeep, for eventual chaving or sharp bends.
Then clear the faults and testdrive to see if the faults come back.
Do you have guarantee on the remanufactured block? A new block cost around USD 280 (www.electricaladvantage.net), but your problem could also be caused by a bad TCM.
 
#19 ·
I thought I was receiving a reman pack but it was obviously a used one When I got it. (Was supposed to even be black plug but wasn't) the guy that owns the place won't even ansew his phone. I got under there and made sure it was connected well yesterday. I'll look at the TCM might take me a bit to locate it.
 
#24 ·
The problem is that you can never rule out any possibility and start with the simple (free) solutions first. You can ofcourse just change parts, but that can become an expensive excercise. It would be a sad story to discover, after changing several parts, that the solution was something simple.
If you would decide to change the solenoid pack again, the address i gave you before is a thrusted one. I bought my solenoid pack there some time ago and they only work with OEM parts for a good price.
 
#26 ·
Yeah, i know. The new fault codes you have now indeed point toward a problem with the solenoid pack, i´m only not completely convinced about the P0750, which is still there.
If you have a multimeter, you could check for continuity and short to ground of the wires between TCM and solenoid pack connectors.
I will attach the schematic in case you want to do so.
 

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#28 ·
Could the TCM possibly need a flash upgrade?
Would not expect so. There is something wrong (could be the TCM as well), but even it the latest flash upgrade was not downloaded, it should not come up with the faults you have now.
 
#32 · (Edited)
You probably refer to the attached TSB. Performing this TSB will add the 5th gear ratio to the 99-00 models (this is just a flash of the TCM, nothing changes to the transmission itself. The 45RFE becomes a 5-45RFE)
 

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