问：700R4传输泵问题是否容易解决？

Hello there, many faults will cause the transmission in your 1990 C2500 to lose forward and reverse gears. The most common causes of transmission issues are low oil level, fluid leaks, shifter linkage faults, or shift solenoids. You stated the need to add transmission fluid, if the oil pump is leaking and fluid was added for that reason the leak will have to be repaired. The best solution is to contact a professional Technician to aide in repair and not driving the vehicle until repairs have been completed to avoid damaging the transmission. A qualified Technician such as one from YourMechanic will be able to diagnose your变速箱故障并进行任何维修。