Here's a breakdown of what to check and how to approach fixing it:
1. Understanding the EST System:
The EST system in your Camaro uses the ECM (Engine Control Module) to adjust the spark timing based on various engine sensors (like the crankshaft position sensor, MAP sensor, etc.). A low voltage condition can stem from multiple sources, preventing the ECM from properly controlling the ignition module.
2. Troubleshooting Steps (in order of likely culprits):
* A. Check for Obvious Wiring Problems:
* Visual Inspection: Carefully examine all wiring related to the EST system. Look for:
* Broken wires: Pay close attention to wires near the distributor, ECM, and any connectors.
* Corrosion: Check connectors for corrosion, especially those exposed to the elements. Clean them with electrical contact cleaner.
* Loose connections: Ensure all connectors are securely plugged in.
* Continuity Test: Use a multimeter to test the continuity of the wires in the EST circuit. You'll need a wiring diagram for your specific Camaro to trace these wires accurately. (A Haynes or Chilton manual will be invaluable here). Discontinuity indicates a broken wire.
* Voltage Drops: Check the voltage at the ECM connector for the EST circuit. You should see battery voltage (around 12V) when the ignition is on. A significant drop points to a wiring issue.
* B. Check the Ignition Control Module (ICM):
* Visual Inspection: Inspect the ICM for any signs of damage (burns, cracks, etc.). The ICM is often located near the distributor.
* Replacement: The ICM is a common failure point. If you find any damage or suspect it's faulty after checking wiring, replacement is the most likely solution. Ensure you get a replacement part that's specifically for your year and model.
* C. Check the Crankshaft Position Sensor (CKP Sensor):
* This sensor provides crucial timing information to the ECM. A faulty CKP sensor will lead to inaccurate timing and throw codes.
* Inspection & Testing: Check the sensor for damage and clean it if necessary. You might need a multimeter to test its output signal (consult a wiring diagram). A replacement might be needed if testing reveals a problem.
* D. Check the ECM (Engine Control Module):
* This is the brain of the operation. While less likely to be the direct cause of a low voltage code 43, a malfunctioning ECM can indirectly cause this code. It's the last resort after checking everything else.
* Diagnosis: ECM diagnosis usually requires specialized tools or professional assistance. You might need to take it to a shop for testing or replacement.
* E. Battery & Charging System: A weak battery or charging system can also cause low voltage conditions that manifest as code 43. Make sure your battery is fully charged and your alternator is working correctly.
Important Considerations:
* Wiring Diagram: You absolutely need a wiring diagram specific to your 1989 Camaro. This will show you the exact location of the components and the wiring paths of the EST circuit.
* Multimeter: A multimeter is essential for testing voltage and continuity.
* Safety: Disconnect the negative battery terminal before working on any electrical components to prevent short circuits or shocks.
If you're not comfortable working with automotive electrical systems, it's best to take your Camaro to a qualified mechanic. Incorrectly diagnosing or repairing this issue could lead to further damage.
