In a previous newsletter called “Similar But Not Identical” the problem of not having line pressure rise was identified by installing solenoids in their wrong location. A no move forward could also accompany this complaint.
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Similarly, after servicing the valve body the vehicle exhibits a slipping in Reverse on throttle up as well but this complaint is accompanied with forward movement having sliding shifts. A line pressure gauge reveals that there is no line pressure rise with throttle opening.
One cause may be that the wrong boost sleeve was used which connects SLT pressure to an exhaust. The U140/240 boost valve sleeve (Figure 1) is configured differently than the U150/250 (Figure 2). Dimensionally the U140/240 boost valve will fit into a U150/250 valve body but due to modest differences, boost pressure will dump to an exhaust preventing any line pressure boost with throttle opening (Figure 3).
This means that even if you unplug the solenoid case connector, line pressure will not rise. This is another case of things that look similar that are mistaken as identical.