I have a 2002 7.3 ltd X with the 4r100 transmission. The trans shifts fine until it get over 160 deg (glow shift gauge in test port) Then the OD stops working and get no engine braking until I turn off the OD. when od is turned off, appears to shift OK. When the trans temp gets below 150, I get the OD back. The OD light did flash on 2 occasions but no code while engine on and light flashing but OD was working at the time. after shutting off engine and restarting light stopped. New fluid and filter, torque convert was flushed also and X has larger 6.0 trans cooler. Tran did get hot once while towing 4 ton trailer 240 f, thus bigger cooler. what would cause the OD to go out when above 160 f but come back when cool?

tmr

 

@Mark Kovalsky might have some ideas.

Stewart

 

I think we will need the codes. I know you said there were none, but there are. I suspect you didn't use the right tool to read transmission codes. Some can read them, and some cannot. I don't have a list of those that will work.

The only thing I can think of is that the OD clutch seals are leaking. They will leak more the hotter the trans gets. But that seems like a very narrow temperature band to stop working and start working again.

How was the torque converter flushed? I don't think it caused this problem, but I'm really curious.

 

Thanks for the response

I first drained the pan and changed the filter then added 6 quarts of mercon fluid. Disconnected the cooler line to the transmission and attached a clear tube to a bucket and started the engine till I began to see air bubbles and shut it down. repeated it until i added 18 quarts reattached the cooler lines then filled to normal hot level.

I have an Actron reader but it probably doesn't display the codes although it indicates that it provides the transmission error codes. I will research which readers will work and get one.

Thanks
Tom

 

Thanks, Mark!

Stewart

 

Mark,

I finally got a BAFX Bluetooth OBDII scan tool and the ForScan app to read the error codes. The transmission code was P0783, the 3-4 gear malfunction, which is what I had experienced. I also had the P0478 and P0470 codes from the EBPV. The tube was plugged and I cleaned it and the sensor. I cleared the codes but still get a P0470 EBP electrical fault. The EBP is 31.5 psi KOEOF, and 33 psi with KOEO. MAP is 14 PSI so I assume the EBP sensor is at fault and will re-clean or replace.

It has been above 90 f so I have been driving the excursion to see i can reproduce the problem. I drove 200 miles mostly interstate with some city driving and no problems. Tran temp got up to 175 f on the hills but no slip.

Today the ambient temp was 95 and I drove about 70 miles tran temp up to 170 and no problems until I stopped for fuel. When getting back on the highway, I sped up faster than normal to merge with traffic and it was fine and it went into OD. With in a couple miles it dropped out of OD and into 3rd and would not go into OD but no flashing light. I drove about 5 miles at 55 mph and pulled into a rest stop and checked the codes. No transmission code but P0478 along with the P0470. Tran temp was 185. I tried to back up and it was like the brake was on. Tran fluid was good. I turned off the engine and sat for 20 min until the tran temp was down to 165. Started up and every thing was back to normal and it shifted fine the rest of the 60 miles home. Any idea what would cause the intermittent transmission problems.

 

This makes me think that the forward clutch won't release.

 

Not too important this time because your actions weren't due to a very high trans temp, but if you ever want to let the transmission cool down, don't shut the engine off, especially if your trans temp is extremely high, because it will just sit there at that same temp and cook the innards of the trans.

Let the engine run so the fluid circulates through the rad cooler and the trans cooler, cooling the trans fluid.

Stewart

 

I have a 2001 F250 7.3 with similar problems. I checked the codes with the Snap On solus edge and found P0476 (exhaust pressure control valve perform), P0783 (3-4 shift error) and P0732 (gear 2 incorrect ratio). the truck also seems to have a torque converter that"s not locking up. I have also experienced problems when trying to use reverse. the problem was it would back up a few feet then the truck acts like the e-brake is on. The next day the reverse problem seems to go away. I have changed the filter and a partial fluid change(only whats in the pan). I used the truck a couple days and everything seemed good till a trailer with a load was pulled then the torque converter problem started again. any ideas? TMR did you solve your transmission/torque converter problem?

 

My guess is that your truck has the original transmission. That trans would most likely have a mechanical diode one way clutch, and I suspect it's failed. That will put small bits of metal throughout the transmission that can cause all sorts of issues. A rebuild is the only fix.

 

Thanks for the quick reply Mark! The transmission has been replaced a few years ago. I bought it from Jasper with the upgraded torque converter. The swap was greater than 100K miles ago. When I bought the transmission, I was told it had many upgrades(whatever that includes). The reverse problem has only happened a couple times. When this happens, the transmission is completely up to temp (maybe even warmer than that). When I pulled the pan to change the filter, the magnet had very little fuzz on it. I'm wondering if the converter is headed south. The truck seems to do good until its pulling a loaded trailer or on longer drives with a unloaded trailer. I was told the P0476 (exhaust pressure control valve perform) code could have something to do with it because of a shared ground. Have you ever heard of this? Thanks again.

 

There is NOTHING electrical that can cause your reverse problem. It has to be something mechanical inside the transmission, or possibly a brake problem.

 

 

That isn't caused by a slipping torque converter. Something mechancial is locking up the transmission.