Signs of transmission trouble include gear malfunctions, a burning smell, leaking fluid, clutch difficulty, unusual noises, slow response and an activated "Check Engine" light, according to HowStuffWorks. Vehicles with transmission problems commonly show multiple symptoms
Gear glitches point to transmission trouble. In a car with a manual transmission, the driver is sometimes unable to shift from one gear to another, HowStuffWorks explains. With either type of transmission, it is a bad sign if a car does not stay in gear but pops into another one spontaneously. Also, vehicles that shake or jolt during shifting need to be checked.
A burning smell sometimes indicates that the transmission is overheating, states HowStuffWorks. Normal fluid is a clear bright red with a sweet smell. Red or brownish spots on the driveway indicate a leaking transmission. In a vehicle with automatic transmission, leaks are confirmed by checking the fluid level with a dipstick. A mechanic is typically needed to check the fluid on a car with a standard shift.
On a manual transmission vehicle, a "dragging clutch" does not disengage during gear shifts, notes HowStuffWorks. It is accompanied by a grinding noise. Other warning sounds include loud noises while in neutral gear and whining, clunking or humming.