* Low Transmission Fluid: This is the first and easiest thing to check. Low fluid can cause a variety of transmission problems, including stalling when under load (like shifting into gear). Check the fluid level with the engine running and warmed up. If it's low, you need to find out *why* it's low (leak, internal problem). Simply adding fluid might mask a more serious issue.
* Torque Converter Issues: The torque converter connects the engine to the transmission. Problems like a failing torque converter clutch or a damaged torque converter can cause stalling when engaging the transmission. This is a more serious issue usually requiring transmission repair or replacement.
* Transmission Solenoids or Sensors: These electrical components control various aspects of the transmission's operation. A faulty solenoid or sensor can prevent the transmission from engaging properly. Diagnosis usually requires a scan tool to check for trouble codes.
* Transmission Internal Problems: Worn-out clutches, bands, or other internal components within the transmission itself can lead to this symptom. This is often a costly repair.
* Engine Problems (Less Likely): While less likely given the specifics, a weak ignition system or a problem with the engine's ability to handle increased load could contribute. However, if it idles perfectly, this is lower on the list of possibilities.
* Vacuum Leaks (Less Likely): While less common, vacuum leaks can affect the transmission's shifting ability, especially in older vehicles. This would usually manifest in other symptoms as well.
What to do:
1. Check the Transmission Fluid: This is the most important first step. Check the level and condition (color, smell). Dirty, burnt-smelling fluid is a bad sign.
2. Get the Transmission Codes Read: A scan tool capable of reading transmission codes is crucial. Auto parts stores often offer free code scanning. This will give you clues about what might be malfunctioning.
3. Inspect for Leaks: Look carefully under the van for any signs of transmission fluid leaks.
4. Professional Diagnosis: If the fluid level is good, and you're getting codes, or you're unsure about the cause, take it to a qualified mechanic specializing in automatic transmissions. This is especially important given the age of the vehicle – further damage is likely if the underlying problem isn't addressed.
Ignoring the problem could lead to complete transmission failure. Getting it diagnosed and repaired promptly is recommended.
