My batt/alt. Light comes on at different intervals?

If you're experiencing intermittent battery/alternator light illumination and associated dimming of headlights and interior lights in your 1992 Ford Tempo, there are a few potential causes to consider:

Loose or Corroded Electrical Connections: Despite cleaning the terminals, there may still be loose or corroded connections elsewhere in the electrical system. Check the battery terminals, alternator connections, and grounding points for any signs of corrosion, looseness, or poor contact. Ensure all connections are secure and clean.

Belt Tension and Condition: Although you've replaced the tensioner and serpentine belt, it's worth double-checking the tension to ensure it's properly adjusted. Additionally, inspect the belt for any signs of wear or damage. A loose or worn belt can affect the charging system's operation, causing intermittent issues.

Voltage Regulator: The voltage regulator is responsible for regulating the output of the alternator and maintaining a steady charging voltage. A malfunctioning voltage regulator can cause inconsistent charging, leading to intermittent battery/alternator light illumination. Consider having the voltage regulator tested or replaced if necessary.

Grounding Issues: Poor grounding connections can result in erratic electrical behavior. Inspect the grounding points throughout the vehicle, including the battery ground, engine ground, and chassis ground. Ensure they are clean, tight, and free from corrosion.

Electrical Load: Pay attention to any specific circumstances or electrical loads that coincide with the light illumination and dimming. For example, if it happens predominantly at night or when certain accessories are in use, there may be an issue with those components, such as a faulty headlight relay or a short circuit.

If the issue persists, it may be beneficial to have a qualified mechanic perform a more in-depth inspection of the electrical system. They can utilize diagnostic tools to measure voltage and current at various points and pinpoint the source of the problem more precisely.

Remember, intermittent electrical issues can be challenging to diagnose, so it's best to consult with a professional who has the expertise and equipment to identify the underlying cause and provide an accurate solution.