Pressure Sensor??
If he has no thermal bypass, I would suspect that sucker!
here is cut and paste...
Common Problems with the 545RFE
Delayed and/or harsh 3-4 or 4-5 shifts
Problem – Owners may experience an unusually delayed or harsh 3-4 or 4-5 gear change, where the transmission doesn’t seem to want to go into that particular gear.
Solution – This issue is related to valve body problems where the material used to make one of the checkballs has broken down to the point that fluid is able to get past and engage the underdrive clutch during those shifts. An upgraded #2 checkball will be needed to solve the issue.
Solenoid Pack: With no transmission bands, the electronically controlled 545RFE relies on a solenoid switch pack to direct fluid to the correct clutch pack for gear engagement. If the solenoid pack goes bad, you’ll experience no gear engagement, engine stalling, ‘limp mode’, or failure to engage overdrive.
Slipping and Delayed Gear Engagement: The transmission pump has a little valve mechanism inside it, which controls the fluid pressure being transferred from the torque converter. If it goes bad, you’ll have delayed gear engagement, transmission/torque converter overheating, stalling, slipping, and reduced fuel economy.
Another common problem is overheating. This happens when the moving parts inside the transmission are creating more friction heat than the ATF can remove. The most common cause of this condition is towing heavy loads, driving in stop/go traffic, or on mountain roads where the transmission has to shift a lot.
Updates to Remanufactured 545RFE Transmissions
- Fully remanufactured valve body includes updated solenoid switch valves for improved shifting, lubrication, and performance.
- Fully remanufactured torque converter is tested for leaks, lockup, concentricity, and balance. Upgrades exceed OE requirements and eliminate the possibility of front seal leaks, premature bushing wear, and vibration.
- Completely remanufactured pump, complete with updated TCC limit valve and TCC accumulator to ensure proper TCC control and cooler flow, provides consistent internal pressures, eliminating slippage and delayed engagement.
- New line pressure sensor maintains consistent shift quality.
- Secured accumulator cover bolts prevent loss of 3rd or 4th gear.
- Fully remanufactured solenoid packs are tested separately from the transmission before dyno testing to verify shift quality and pressure control.
- All-new custom-spec bushings improve internal fluid flow control and pressures.
- Bushings and machined surfaces polished to a mirror-like OE finish of 16 RA or less.
- Complete system correction and recalibration kit installed to address several OE flaws. Modifications include updates to servos, the PR system, and valve body accumulators.
- Heavy-duty recalibration kit installed to reduce slippage and increase durability.
- Complete road simulation using a dynamometer testing program called C.A.R.S. (Computer Aided Road Simulation). Every transmission is cold and hot tested before shipment.