Why is my battery light coming on and off when it's raining?

A car's battery light, also known as the dashboard battery indicator, indicates a charging problem with the battery. The light may come on for a number of reasons, including:

• A damaged or worn out battery
• A malfunctioning charging system
• A broken alternator belt
• Damaged battery cells
• A failed alternator
• A corroded battery terminal
• A faulty battery cable
• Wiring issues

You did mention this only happens when its "raining" This would indicate that perhaps some water is making its way to a loose connection and shorting the system.

To troubleshoot this yourself there are some steps to take before you take it to a professional. However in the PT Cruiser the engine has a pretty tight fit from my memory.

Step 1. Pop the hood and inspect the battery terminals. do they seem tight. are they extensively corroded or have broken wires?

Step 2. Put a voltage tester on the battery terminals and set it for DC voltage. What is the current reading? is it 12-12.5 volts?

Step 3. Start the vehicle and while it is running again place the tester on the battery terminals. What is the current reading now? 14-14.5 volts?

Shut Off Car -- Remove Keys, Lock the Door and if it has remote start disconnect the battery. You don't want it starting while your hands are near the belts.

Step 4. Locate the Alternator it will be on the left side when facing the engine from the front.

Step 5. Does the serpentine belt look ok? There should be a connector and a larger wire attached to the alternator are those tight?

If you have been through these steps and still haven't found a problem you can take your vehicle to an Autozone, Napa or advanced auto and one of their clerks will hook the battery to a tester independently and also maybe the alternator to see if either of those units are failing. They will usually do this free of charge and possibly place the car on a diagnostic scanner to see if any codes have registered with the vehicle.

Otherwise you will have to have a diagnostic visit to your local mechanic.

I hope this helps

Cheers!!

Monte