Here's a systematic approach to troubleshooting, starting with the simplest and safest checks:
1. Battery Connections:
* Clean the terminals: Corrosion on the battery terminals is a VERY common cause of electrical problems. Use a wire brush or terminal cleaner to thoroughly clean both the battery posts and the cable clamps. Make sure the connections are tight.
2. Battery Voltage:
* Check battery voltage: Use a multimeter to measure the voltage directly at the battery terminals. It should read around 12.6 volts when the car is off. If it's significantly lower, the battery is likely dead or needs charging.
3. Main Power Wire:
* Trace the main power cable: This is the heavy-gauge cable running from the positive (+) battery terminal. Follow it to see where it connects to the starter solenoid and the rest of the car’s electrical system. Look for any breaks, corrosion, or loose connections. This cable is usually protected by a fusible link, which you should inspect carefully too. A fusible link looks like a short length of smaller-gauge wire that might be a different color than the main cable itself; it's designed to melt and break the circuit if there is excessive current draw.
4. Ignition Switch:
* Check the ignition switch: This is a common failure point. It's located under the steering column. You can test it by using a voltmeter to see if you're getting power to the switch in the "on" position and at the output when the key is turned. Caution: Disconnect the battery negative (-) terminal before working on the ignition switch.
5. Starter Solenoid:
* Inspect the starter solenoid: While you can crank the engine with a screwdriver, the solenoid might be failing to engage properly when the ignition key is turned, hence no power going to the rest of the system.
6. Fuses and Circuit Breakers:
* Check fuses and circuit breakers: There are several fuse boxes in the 78 Camaro. Locate them and inspect the fuses. Look for blown fuses (the fuse element will be broken). Replace any blown fuses with fuses of the correct amperage rating. Some circuits may be protected by circuit breakers instead of fuses.
7. Main Power Relay (if applicable):
* Some vehicles use a main power relay. This is a small electrical switch that controls the flow of power to the main circuits. Locate it and inspect it for functionality.
Safety Precautions:
* Disconnect the negative (-) battery terminal before doing any electrical work. This will prevent accidental shorts and protect you from electric shock.
* If you're not comfortable working with car electrical systems, it is highly recommended to consult a qualified mechanic. Incorrect repairs can cause further damage.
* Always use the correct amperage fuses when replacing them. Using an incorrect fuse can lead to fires.
If you've checked all of these and still have no power, the problem is likely more complex and may involve a wiring fault somewhere in the car's harness. A wiring diagram specific to your 1978 Camaro would be incredibly helpful at this point. You can often find these online (through forums or parts suppliers) or in a repair manual.
