Many charging system complaints stem from easily repairable problems that reveal themselves during a visual inspection of the system. Remember to always look for the simple solution before performing more involved diagnostic procedures. Use the following inspection procedure when a problem is suspected.

  • Check for corroded or broken wire connections. Many automotive electrical systems contain fusible links to protect against overloads. Fusible links can blow like a fuse without being noticed. Also, look for a short circuit, an open ground, or high resistance in any of the circuits that could cause a problem that would appear to be in the charging system.
  • Wiggle wires while the engine is running. Have an assistant sit inside the car to see if an indicator light goes out or a gauge begins to read correctly.
  • Listen for noises as the engine runs. Be careful not to use a stethoscope close to alternator wiring.
  • Look for a loose or damaged alternator drive belt.
  • Inspect the battery. It might be necessary to charge the battery to restore it to a fully charged state. If the battery cannot be charged, it must be replaced. Also, make sure the posts and cable clamps are clean and tight, since a bad connection can cause reduced current flow.
  • Inspect the AC generator and regulator mountings for loose or missing bolts. Replace or tighten as needed. Remember that the circuit completes itself through the ground of the AC generator and regulator. Most AC generators and regulators complete their ground through their mountings. If the mountings are not clean and tight, a high resistance ground will result.

If the vehicle passes all preliminary visual checks, listen for noisy belts, bad bearings, or the whining sound of a bad diode. If no unusual sounds are heard, it is time to test the charging system.