I. Simple Checks (Do these first):
* Battery: This is the most common culprit. Check the battery terminals for corrosion (clean them with a wire brush if necessary) and have the battery tested at an auto parts store to ensure it's holding a charge. A weak battery can crank slowly or not at all.
* Battery Cables: Check the cables for looseness, corrosion, or damage. Poor connections can prevent the starter from getting enough power.
* Starter Motor: A failing starter can result in a clicking sound when you turn the key, slow cranking, or no cranking at all. This requires more advanced diagnosis.
* Alternator: While this doesn't directly prevent starting, a bad alternator might have left the battery completely drained. Have it tested as well.
* Fuses and Relays: Check the fuses and relays related to the ignition system. A blown fuse or faulty relay will interrupt power to crucial components. Consult your owner's manual for fuse box locations and diagrams.
* Ignition Switch: A faulty ignition switch can prevent power from reaching the starter. This is often diagnosed by testing the switch itself or its circuits.
* Neutral Safety Switch (Automatic Transmission): This switch prevents starting unless the gear selector is in Park or Neutral. If your Tahoe has an automatic transmission, ensure the shifter is in the correct position.
* Fuel: Check the fuel gauge and make sure you have fuel in the tank. Sounds obvious, but easily overlooked!
II. More Complex Issues (Require more troubleshooting):
* Security System: If equipped with an aftermarket or factory alarm system, a malfunction could be preventing the vehicle from starting.
* Ignition Coil: This component provides the spark to ignite the fuel/air mixture. A faulty coil will prevent the engine from firing.
* Distributor (if equipped): Older vehicles may have distributors. Problems with the distributor cap, rotor, or ignition module can prevent starting.
* Crankshaft Position Sensor (CKP): This sensor tells the computer the position of the crankshaft, vital for proper ignition timing. A faulty sensor will prevent starting.
* Cam Position Sensor (CMP): Similar to the CKP, this sensor is also critical for ignition timing.
* Fuel Pump: A faulty fuel pump won't deliver fuel to the engine. You might hear a buzzing sound from the fuel pump when you turn the key (if it's trying to work).
* Fuel Injectors: Clogged or faulty fuel injectors will prevent fuel delivery.
* Computer (PCM/ECM): A faulty engine control module can cause a variety of starting problems. This is a more advanced diagnosis typically requiring a scan tool.
Troubleshooting Steps:
1. Start with the simple checks: Battery, cables, fuses, fuel level.
2. Listen carefully: Do you hear any clicking, buzzing, or grinding noises when you turn the key? This can provide clues.
3. Visual inspection: Look for any obvious signs of damage to wires, connectors, or components.
4. Use a multimeter: If you have one, you can test the battery voltage, check for power at various points in the ignition system, and test the continuity of circuits.
5. Consult a repair manual: A repair manual specific to your 1996 Chevy Tahoe will provide detailed diagrams and troubleshooting procedures.
6. Seek professional help: If you can't diagnose the problem yourself, take your Tahoe to a qualified mechanic.
Remember safety first! Work on your vehicle in a well-ventilated area and disconnect the negative battery terminal before performing any electrical work.
