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Discussion Starter · #1 ·
Hi everyone, I’m new to this site and I was hoping maybe someone can offer some advise. I apologize for the long post but I wanted to include as much detail as possible.

My son recently purchased an early 99 (4/1998) F350 DRW 7.3l 4R100 4x4 with 236K miles. The problem is it will not shift beyond 2nd gear. At 233K miles the original owner lost all forward gears with only reverse left. He took the truck to a repair shop that works on his company vehicles and they installed a Jasper Reman transmission. He picked up the truck (this is his personal truck) and drove it for around 1500 miles and then started having problems with it not shifting beyond 2nd gear. He took it back to the shop where they installed another Jasper Reman transmission under warranty and it still did not shift beyond 2nd gear. Supposedly they reflashed the ECM and it started shifting fine again for another 1500 or so miles and the same problem came back. He took the truck back and they could not find the culprit. At this point he needed a dependable truck and purchased a new one. My son had been looking for a nice 7.3 truck and he took a chance with this one.

I’m a mechanic and have been trying to help my son work out this issue. First off the truck has 1st, 2nd, and reverse. The trans fluid is clean and full. There are no codes stored and the O.D. Light is not flashing. I have checked both the input and output speed sensors and they are a steady 1.8K ohms. The ABS sensor is a steady 1.5K ohms. The truck runs well and shifts well from first to second and into reverse too.

My sons friend is a transmission mechanic at a local shop. He could not find any codes stored with his scanner. On the test drive he could see the ECM commanding 1st gear , 2nd gear, and then 3rd gear but it obviously was not shifting into 3rd. His scanner was showing that the ECM thought it was in 3rd then it commanded a 4th gear shift but it still was in 2nd gear. The friend is stumped too

My son and I have researched the solenoid shift strategy and we know both valves are working since we have 1st and 2nd gear. We found some information that instructed to unplug the solenoid harness on the right rear of the transmission to simulate a 4th gear shift, so we unplugged the harness and drove the truck around the neighborhood block in 4th gear confirming that we have a 4th gear in this Jasper Reman transmission. We understand the shift strategy to be as follows

1st. SS1 on SS2 off
2nd SS2 on SS2 on
3rd SS1 off SS2 on
4th SS1 off SS2 off (what we were able to mimic with an unplugged solenoid harness)

Any help that you could provide would be greatly appreciated.

Thank you
 

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Discussion Starter · #6 ·
Your TSS divided by OSS shows a ratio of 1.54:1. That's second gear. So it's commanding third, but not shifting out of second.

Does reverse work correctly? If so, that shows that the direct clutch is working. The direct is used for third gear and reverse. If reverse works I would suspect a stuck 2-3 shift valve in the valve body. If reverse doesn't work, the direct clutch is hosed. Not commanding fourth gear is because it won't shift to third gear.
Hi Mark, yes reverse works correctly and seems to be strong. I forgot to mention in my previous post that after the P0782 code was thrown the OD light did begin to blink on the shifter. I cleared the code but it sounds like it is all related to what you are saying about the 2-3 shift valve being stuck. I will look into replacing this valve and getting back with you on the results. Thank you
 

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Discussion Starter · #7 ·
Hi Mark, yes reverse works correctly and seems to be strong. I forgot to mention in my previous post that after the P0782 code was thrown the OD light did begin to blink on the shifter. I cleared the code but it sounds like it is all related to what you are saying about the 2-3 shift valve being stuck. I will look into replacing this valve and getting back with you on the results. Thank you
Your TSS divided by OSS shows a ratio of 1.54:1. That's second gear. So it's commanding third, but not shifting out of second.

Does reverse work correctly? If so, that shows that the direct clutch is working. The direct is used for third gear and reverse. If reverse works I would suspect a stuck 2-3 shift valve in the valve body. If reverse doesn't work, the direct clutch is hosed. Not commanding fourth gear is because it won't shift to third gear.
Hi Mark, yes reverse does work correctly. This weekend I was able to check the valve body. I unfortunately did not find a stuck 2-3 shift valve. All of the other valves seem to be moving freely in the valve body and the spring action feels equal between all of them. I had ordered the updated 2-3 shift valve from transgo so I did install it with the new supplied spring.

I pulled the Accumulator body and found that the modulating valve was sticking so I polished the bore and valve with 2000 grit wet sandpaper and it moves freely now. All of the other valves move freely and they all have equal spring pressure in the valve body.

When I drained the fluid I found very small fiber and some small metallic particles in the fluid. I did find a few larger pieces of metal in the fluid but it was not much at all. The one thing that stood out was the bottom of the solenoid pack did not have the protective cover that goes over the soldered connections.

We put it all back together and torqued to spec. Filled it with fluid and unfortunately we still do not have 3rd gear. Is there any way that we could have something wrong with the solenoid pack?

Thank you for your help Mark
 

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Discussion Starter · #9 ·
A problem with the solenoids should set a code. I can't rule out the solenoids, but it sure doesn't seem likely.

This is a puzzler. Since reverse works, we know the direct clutch works. When the trans makes a 2-3 shift all it does is apply the direct clutch. Maybe there is a leak in the solenoids or the gasket for the solenoid body. The direct clutch is applied by the solenoid for a 2-3 shift, but is applied by a hydraulic circuit without the solenoid in reverse.
Hi Mark, Yes it is a puzzler!! I have obviously been thinking about this problem for a while now and how the transmission was shifting fine and then all of a sudden it just stopped all within 400 miles of being installed. After we have been exchanging info back and forth and seeing the data log on the scanner while driving it is starting to make sense as to why the ecm will command a 3rd gear shift and then a 4th gear shift (it has commanded a 4th gear shift 2 times in my data log recording sessions)but it is not happening because of a pressure lose after the Solenoid Pack going to the direct clutch. I’m grabbing at straws but what you are describing in your last post is making sense to what I have been pondering. Do you have any recommendations on any particular Solenoid packs?
 

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Discussion Starter · #12 ·
No, I don't. But I suspect it is a gasket, not the solenoids.
Hi Mark, I wanted to thank you for all of your help. I joined this site hoping that you would read our post and offer your valuable advice to help solve our issue. Well this afternoon i drained the fluid, removed the pan and the solenoid pack to examine the condition of the gasket underneath it. Upon closer examination I could not find any damage or deformation to the gasket or the solenoid pack gasket surface. Last night I did purchase a new solenoid pack made by Standard Automotive parts and performed a continuity check on both units to compare the readings. Both of them are for PWM TC Solenoids and they tested fine. What I did notice was how bad the soldered connections looked on the suspect pack from Jasper. Some of the pieces felt loose including the connection socket that passes through the transmission body. After finding that my son and I agreed to install the new solenoid pack. So we torqued everything to spec as we put it back together then refiledl it with fluid and went for a drive. We jumped for joy when she shifted into 3rd gear at around 30mph and then 4th at around 45 mph!! We took the truck on a 10 mile test drive just to make sure everything was operating properly and she shifted great!! Thank you again for all of your help Mark!! We would still be scratching our heads without your guidance.
 
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