I keep getting a blinking d4 and code p1758. If I erase code the car works perfectly for 5-15 miles. Then CEL comes on and d4 starts blinking. Sometimes transmission still works perfect, and sometimes will not hit overdrive. Lockup solenoids have 14.7 ohms in each, and both click when energised. I am assuming there is a sensor not giving it the signal to open or close. Any ideas?