According to automotive website Samarins.com, the automatic transmission in a vehicle is one of the most difficult and expensive fixes on a car. As a result, many problems associated with automatic transmissions can only be fixed by a mechanic with experience in transmission work. However, on a Nissan (as is the case for most other cars with automatic transmissions), a few troubleshooting tricks that can be used to identify some of the easier fixes on a failing automatic transmissions.
Remove buildup and grime around your Nissan's engine and transmission using automotive solvent and engine cleaning degreaser so transmission leaks can be more easily detected. Some leaks can be fixed by the do-it-yourself mechanic, while others are more complex and may require professional service. According to the Haynes Repair Manual for the Nissan Maxima, common transmission leaks occur on the bottom half of the transmission pan, the dipstick tube, transaxle oil lines, speed sensor and the oil seals on the drive axle.
Warm up your Nissan's engine until the tachometer is idling between 400 and 800 rpm. Pull out the transmission dipstick and wipe it clean. Re-insert the dipstick into the transmission tube and pull it back out, inspecting the fluid level on the dipstick. Add more Dexron VI automatic transmission fluid using a funnel inserted into the dipstick tube until the fluid level is between the min and max lines on the dipstick.
Inspect the quality of the transmission fluid on the dipstick. If it is burnt or smells like burnt toast, it means the transmission has recently overheated. If the fluid has a black or dark brown appearance rather than a deep red color, it is old and needs to be drained and replaced. Bad or low transmission fluid may account for delayed, rough or erratic shifting and slipping or missing gears.
Turn on your engine to see if it will start in gears other than park or neutral. If your Nissan starts in drive or first, second or third gear, your neutral safety switch is either malfunctioning or needs adjustment. Replacing the neutral safety switch is often a job that can be done by the do-it-yourself mechanic.
