Possible Causes:
* Worn or Damaged Park/Neutral Safety Switch (PNSS): This is the most frequent cause. Over time, the switch can wear out, its internal components can fail, or it can become misaligned. This prevents the switch from reliably signaling the correct gear position to the vehicle's computer.
* Shift Cable Adjustment: The cables that connect the shifter to the transmission can become stretched, broken, or improperly adjusted. This can lead to inaccurate gear selection and the PNSS not registering "Park" correctly.
* Transmission Linkage Problems: Issues with the linkage connecting the shifter to the transmission itself can cause similar problems to the shift cable adjustment. This might involve bent or broken components.
* Low Transmission Fluid: While less likely to directly cause sticking in park, low transmission fluid can affect the smooth operation of the transmission and potentially contribute to the problem indirectly.
* Damaged Shift Lever: In rare cases, damage or wear to the shift lever itself can interfere with proper gear selection.
* Electrical Issues: Problems with the wiring harness connected to the PNSS can also cause intermittent failures. This may include corroded connectors or broken wires.
Repair Options:
1. Check Transmission Fluid: Start by checking the transmission fluid level. Low fluid can cause a multitude of transmission problems. Add fluid if needed, but if the level is significantly low, investigate the cause of the leak.
2. Inspect Shift Cables and Linkage: Visually inspect the shift cables and linkage for any signs of damage, stretching, or misalignment. Adjust the cables if they're loose or out of adjustment (refer to your repair manual for proper adjustment procedures). Replacement may be necessary if they're damaged.
3. Replace the Park/Neutral Safety Switch (PNSS): This is often the solution. The PNSS is relatively inexpensive and easy to replace for someone with basic mechanical skills. You'll likely need to consult a repair manual for your specific Tahoe model to locate the switch and follow the correct replacement procedure. Often, this involves removing the shift lever console to access it.
4. Address Electrical Issues: If the switch itself seems fine, check the wiring harness connected to it for corrosion or damage. Repair or replace as needed.
5. Transmission Repair (Last Resort): In rare cases, the problem may stem from internal transmission issues. This is the most expensive and complex repair option and should only be considered if the other solutions don't resolve the problem.
Important Notes:
* Safety First: Always disconnect the negative battery terminal before working on any electrical components.
* Repair Manual: A repair manual specific to your 1997 Chevy Tahoe is highly recommended. It will provide detailed diagrams, instructions, and torque specifications for all the repair procedures mentioned above.
* Professional Help: If you're not comfortable working on your vehicle yourself, take it to a qualified mechanic.
The PNSS is the most likely culprit, but a methodical approach, starting with the easiest and least expensive checks, is the best way to tackle this problem. Don't skip steps! Fixing a small issue early can prevent bigger (and more expensive) ones later.
