Q: I have a short that drains the battery overnight.

asked by on

I have tested from negative battery terminal to negative cable using a 12V test light, but the light doesn't go out when I pull the fuses. Also, I get a lot of static in the radio when I rev the engine. Wondered if it might be a diode in the alternator??

My car has 135000 miles.
My car has an automatic transmission.

There is a parasitic load applied to your battery with the ignition is off. Keep the test light on the battery and turn on one thing at a time and watch the light. If the light goes out, then that issue is the problem. Be sure to have your doors shut and open them to verify the door light switches. If nothing is turning off the light, then remove the power supply harness to the alternator and see if the light goes out. If it does, then the windings inside the alternator are bad and pulling the battery down. If you need further assistance with a parasitic load, then seek out a professional, such as one from Your Mechanic, to help you.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. I have a short that drains the battery overnight.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: My transmission seems to be slipping or something else...?

This may be a simple adjustment to the throttle kick down on the transmission. It may be out of adjustment or there may be a problem with the shift solenoids in the transmission. The kick down is a simple adjustment...

Q: Battery runs down in two days if the engine is not running. The alternator has 14 volts.

Hi there. It seems that there is a parasitic load on your vehicle's battery when the vehicle is sitting and not running. Check the battery for a voltage and see if the charge is 12.6 volts. If the battery is...

Q: I replaced the battery, alternator, did a tune up and changed the fuel filter. The truck still has trouble starting

A hard start or stall after starting is most likely caused by a fuel pump that is not holding pressure up to the fuel injectors after you shut off the engine. The fuel pressure should be tested to verify the...

Related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...