Transmission Related:
* Low Transmission Fluid: This is the most common and easiest to check. Low fluid leads to insufficient lubrication and pressure, causing harsh shifts. Check the fluid level while the engine is running and warmed up. Note the color and smell; burnt fluid indicates a more serious problem.
* Contaminated Transmission Fluid: Dirty or burnt transmission fluid can't lubricate properly and can clog valves and passages within the transmission. A fluid change with a filter replacement is often the solution, but severe contamination may require a rebuild or replacement.
* Worn Valve Body: The valve body controls fluid flow within the transmission. Worn or damaged valves can cause incorrect shifting. This usually requires a rebuild or replacement of the valve body.
* Worn Clutch Packs: The clutch packs are responsible for engaging the gears. Wear leads to slippage and harsh shifting. This is a more serious problem requiring a transmission rebuild or replacement.
* Low or Faulty Torque Converter: The torque converter transfers power from the engine to the transmission. Problems here can manifest as harsh shifting, especially in the lower gears.
* Internal Transmission Problems: More extensive internal damage, such as worn planetary gears or other internal components, can also cause hard shifts. This usually necessitates a major transmission repair or replacement.
Engine Related (Less Likely but Possible):
* Engine Mounts: Worn engine mounts can cause excessive vibration, which might be felt as harsher shifting. Check for excessive engine movement.
* Throttle Position Sensor (TPS): A faulty TPS can send incorrect signals to the transmission control module (TCM), leading to improper shifting.
Other Potential Causes:
* Transmission Control Module (TCM): Problems with the TCM can disrupt the signals controlling the transmission's operation. This is less common but possible.
Troubleshooting Steps:
1. Check the transmission fluid level and condition: This is the first and most important step.
2. Inspect for leaks: Look for any leaks around the transmission pan or elsewhere.
3. Have the transmission fluid and filter changed: This is a relatively inexpensive fix that can often resolve mild shifting problems.
4. Have a professional diagnose the problem: If the fluid level and condition are good, and a fluid change doesn't resolve the issue, you'll likely need a professional mechanic with experience in automatic transmissions to diagnose the problem. They may use a scanner to check for transmission codes.
Important Note: Ignoring hard shifting can lead to more significant and costly transmission damage. Address the problem promptly.
