Tom

Dear    Tom,

Q I own a 2002 Jeep Grand Cherokee. The transmission doesn’t shift to

higher gears unless I rev it up to 4,000 rpm. Why is that?

Kelly—Detroit,  Michigan

Kelly,

A You need to get the vehicle to a shop and have the system scanned for

codes for transmission malfunction. These vehicles are noted for pressure
solenoid failures, causing the symptoms you described. The fluid pressure
solenoid controls oil flow based on electrical commands it receives from the
ECM. If it malfunctions, erratic shift patterns occur. Good luck.