rlpeterson2013

I am the proud owner of a 2008 Dodge 3500 4x4 6.7 Cummins (Blutec) with the 68rfe 6 spd transmission. For the last few months it will not shift past 4th gear when towing a load....or if you load it by accelleration. If I stop the truck and turn off the ignition the transmission will begin shifting correctly again until I load it up. After doing some research I thought that replacing the solenoid block might correct the problem but it did not. Also ... I should mention that I did a delete about 3 years ago and have a smarty tuner. It has always been set in the economy mode and has seemed to work great. I used the tuner to pull the DTC codes and it show P0700 (MIL Request) Transmission Control Malfunction. Also.... The electronic shift switch on the shift lever quit working about the same time. Does anyone have any ideas? Where is the transmission control module located ...is it internal? Could it be as simple as the that switch being bad and somehow affecting the TCM? Would reprogramming the ECM back to stock affect the TCM?

mega-engr

The TCM is separate from the main computer but they communicate. The TCM found an issue and reported it to the ECM, and that is all (in addition to the switch issue which may contribute or be separate) so I would take it in and get the TCM scanned to see what the issue is with the TCM.

rlpeterson2013

I went to the Auto supply and they helped me pull these addition codes:


P0218
P0706 - Transmission range sensor rationality
P0740- TCC out of range
P0871 - OD pressure switch rationallity


I already replace the solenoid block.... I'm guessing that replacing the valve body might be the answer to my problems. Does anyone have experience with this?

mechkev69

Rlpeterson2013 did you ever get your problem fixed and if so what was it my truck seem to be doing something along those lines aswell

RICKYWA

Have your over drive pressure switch checked out by someone who knows what they're doing.

XLR8ER

Not sure why this post fell dead, I'm having the same issues with the same truck. Can anyone suggest a retailer to purchase a new style OR performance valve body. It looks to me like there are no modified/performance valve bodies out there.

mechkev69

I just replaced my solenoid pack on top of my valve body last weekend put a new maghytech oil pan to help keep it cooler and a sonnax line pressure booster. my trans shifts ALOT better and is definitely running a little cooler but I will be doing some moderate towing this weekend so I guess we will see. The line pressure booster definitely decreased the amount of time between shifts and made the ***** a lot more firm. I like what I'm seeing from my trans so far...

XLR8ER

Can I assume that the solenoid pack where the high pressure solenoid (thats seems to be causing issues for the 68rfe's) is located? I see BD has kit to increase pressure and Ive seen some solenoids around like this one.

Transmission Solenoid Block Pack Updated Design New 45RFE 545RFE 68RFE | eBay

XLR8ER

I just now found Sonnax, It looks like they have all my answers for sure. I'll give em a call.

Thanks for pointing them out to me.

JimC

The below info is from another Forum and Transengineer is a dodge tech with some good info. His recommendation on all of the early 68RFE's is to replace the VB before you hit 100K he says they tend to fail after that.


Originally Posted by jimc3165
Quote:
Originally Posted by TransEngineer
Quote:
Originally Posted by jimc3165
TE, I have a 2007.5 RAM and have been reading about things to do to make my tranny last longer. I have had only 1 thing happen to make me think mine is getting weak. Last year I was towing my 5th wheel and when going up hill and accelerating to maintain speed. It sounded like I was run over rumble strips.I quickly let off the gas and remembered that I forgot to program the computer for heavy tow. I pulled into a rest area and reprogrammed the computer and no more problems. However I have been reading your post about the 68RFE and am thinking my valve body and solenoid pack needs to be replaced. My truck is a DD and I tow my RV occasionally but it has never been raced (aside from the occasional hard acceleration) and I try not to be rough on it. Is the VB change pretty straight forward? I have never been a trans guy but do have a mechanical background so I'm thinking it is something I could tackle. What is your take on all of this. Truck has 125K on the OD and has had the fluid and filters changed by the dealership once.
Jim,

I would not be too concerned about the "rumble strips". You were probably slipping the Torque Converter Clutch (TCC), due to operating at high torque but low engine speed. This is fairly common, and although it feels bad, the slippage is not normally enough to do any significant damage (especially if you immediately back off it). If it happens again, just downshift the trans manually and that should eliminate it. Running in a Tow mode shift schedule will likely keep you in a lower gear anyway, so that will also avoid the TCC shudder.

Nevertheless, I think replacing (or at least, checking) the valve body would be a good idea. Worn Solenoid Switch Valve (SSV) bores are very common at high mileage. So if I were you, I would drop the pan, drop the valve body (which is very easy, only 6 bolts; getting the wiring harness disconnected is the hardest part!), and check the SSV bore. You will need a bore gauge to check the bore size (or just see if the plugs are "loose" in the bore). You can change the fluid and filters again while you're in there.

On top of the valve body is a sliding code plate (that moves when you run the shift lever back and forth). Inside the center “chunk” of the valve body, underneath this sliding plate, are two valves - the manual valve (which has a pin that engages the slot in the code plate - this is the valve that moves when you move the shift lever) and the SSV. The SSV is retained by a rectangular plastic retainer, and it has three (3) barrel-shaped plugs at the outer end of its bore. You want to check the size of the four (4) outer lands in this bore (where the plugs slide). The diameter should be 11.544 mm (0.454 inch) max. The plugs should slide THROUGH the bore easily, but they should not WOBBLE or TILT in the bore AT ALL. Clearance between the plugs and the bore should be about .001 inch. The very outer bore should be OK; it is the ones inside that get worn. If any of the lands are worn oversize, replace the entire VB assy with a new Mopar VB.

Make SURE when you reinstall the VB that the slot on the code plate's vertical arm lines up with the pin on the manual lever (the one inside the case, that rotates when you move the shift lever). Leave the shift lever in Park when you pull the VB, and then make sure the code plate is slid to the Park position (fully rearward, with detent roller up against the code plate's vertical arm) before you bolt it in. If it's not lined up correctly, you will break off the pin on the lever, and then you have to pull the trans and tear it down completely in order to replace the lever!

Good luck!

Mark
aka TransEngineer
Mark, thanks for the input, I will probably just replace the VB and be done with it.My plan is to keep this truck for a very long time. Can you provide the correct Mopar part# ?
Thanks again
Jim
Mopar VB is RL033980AC. That is a brand new VB assy (and includes a new solenoid). List price is $675. You can also get a reman VB assy (R8033980AC), which is $577 list, but they are out of stock at the moment.

Another option (especially if you find it hard to get the 68RFE VB) is to buy a VB assy for a 545RFE trans. That is RL166834AD (also brand new) and lists for $605. If you get that one, remove the accumulator cover plate (on the side of the VB) and swap in the springs from your old VB into the new one. The only difference between the 68RFE and 545RFE VBs is these accumulator springs. Easy swap and you save $70 to boot!

mechkev69

Well I towed my trailer for the first time this weekend after doing the solenoid pack change and fluid and filters and a sonnax line pressure booster and wouldn't you know it as soon as the fluid reached around 200 degrees the truck would not stay out of limp mode and gave me the good old p0871 trans code and the p0700 and p0868 soooo...... Looks like a valve body is in my future👎🏻👎🏻👎🏻👎🏻

Busboy

Towing my 13,700lb 5ver Rv with my 2011 68RFE the hottest temps I see are 73C or about 164F and I can read it any time on the mini max.

mechkev69

Well just changed out my valve body assembly... Luckily I found the last one in southern Cali ... So after a fluid and filter change the first time then a fluid, filter, solenoid pack, maghytec trans pan, sonnax pressure booster the second time and now a valve body assembly, solenoid pack and filter change again I think we got it right just towed my trailer up the biggest grade in San Diego county with NO problems and I wasn't goin easy on it at all !!!!! No limp mode, good solid shifts, no over heating I think we are in the clear... Only got a p0868 code which is the low line pressure code but it's kind of a weird one to get cause I put one of those line pressure booster connectors on it sooo... Idk what's up with that... I jut want to thank every body who posts on these forums every bodies insights and conversations were helpful

mega-engr

I would look into that code so as to not toast the tranny down the road...