Transmission-Related Issues:
* Low Transmission Fluid: This is the *first* thing to check. Low fluid can lead to insufficient lubrication, causing the transmission to struggle and stall the engine. Check the fluid level (with the engine running) and its condition (color, smell – burnt fluid is a bad sign). If low, add fluid of the correct type (check your owner's manual). However, *don't* just add fluid without checking for leaks first.
* Transmission Fluid Contamination: Besides low fluid, dirty or contaminated fluid can cause significant problems. The fluid should be reddish-pink; if it's dark brown or black, smells burnt, or has debris in it, a transmission fluid change (and potentially a filter replacement) is necessary.
* Worn Clutch Pack(s) or Bands: These are internal components that wear over time. Worn clutches can slip, causing the engine to stall or rev without power transfer. This requires a transmission overhaul or replacement.
* Torque Converter Issues: The torque converter transfers power from the engine to the transmission. Problems within the torque converter (e.g., damage or failure) can prevent the engine from smoothly engaging the transmission. This is a serious issue requiring professional repair.
* Valve Body Problems: The valve body controls fluid flow within the transmission. Malfunctioning valves can cause various shifting problems, including stalling on engagement. This is also a complex internal transmission issue.
Engine-Related Issues (though less likely given the symptoms):
* Low Engine Oil Pressure: While less probable, severely low engine oil pressure could affect the engine's ability to power the transmission, particularly if the engine is already weak. Check your oil level and pressure.
Other Possibilities:
* Broken or Worn Motor Mounts: Worn engine mounts can cause excessive vibration, potentially disrupting the engagement process. Inspect the motor mounts for damage.
* Electrical Issues: While less likely to cause a complete stall, a problem with the neutral safety switch (prevents starting in gear) or a related sensor could prevent proper transmission engagement.
Troubleshooting Steps:
1. Check Transmission Fluid: This is the absolute first step. Low or contaminated fluid is the easiest (and cheapest) fix.
2. Check Engine Oil Level and Pressure: Rule out low engine oil pressure.
3. Inspect Motor Mounts: Look for visible damage or excessive movement.
4. Listen Carefully: Does the engine crank but not start, or does it struggle to turn over when put into gear? This helps narrow down the problem area.
5. Professional Inspection: Given the age of the vehicle and the severity of the problem, a professional mechanic should diagnose the issue. They have the tools and expertise to determine if the problem is a simple fluid level issue, or a more complex internal transmission problem requiring a rebuild or replacement.
Don't attempt extensive DIY repairs unless you have significant experience working on transmissions. Transmission repair can be complex and expensive. If the transmission fluid is low or contaminated, addressing that first might provide a temporary solution to allow for transport to a repair shop.
