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What happens when you disconnect the negative battery cable?
Disconnecting your car battery will not cause any permanent damage to your computer or ECU (electronic control unit), but it can have some adverse effects. Those include canceling your preset radio stations, forgetting learned shift points, and your car’s ideal fuel/air mixture.
Can you disconnect only the negative terminal?
In order to disconnect the battery, all you have to do is remove the cable from the negative port. Do not let the negative and positive cable ends touch under any circumstances.
Can a battery drain with the negative cable disconnected?
Be safe: always disconnect negative first. Disconnected either terminal will prevent drain, as stated already. A battery tender is another safe way to maintain the battery.
Can a car battery drain with the negative cable disconnected?
That is true. If you were to leave both cables hooked up, your car would likely be dead after about 2 to 4 weeks due to “parasitic draw”. Parasitic draw is all of the computer systems on modern cars that will draw energy from your battery even though your car is turned off.
What causes a car to start after disconnecting the battery?
Click to expand… Weak battery and poor connection at the terminals (dirty, corroded). That ‘click’ is very telling. Take the clamps off, clean the posts and the clamps with a wire brush, snadpaper or whatever and put it all back together. Speaking of corrosion, that sh!t is like cancer in the way it spreads.
What’s the best way to disconnect a car battery?
Disconnect the negative battery cable and then the positive cable with a combination wrench. Clean the battery posts and terminals with the post and terminal cleaning tool, so you have a good connection when you’re done.
What happens to the PCM when the battery is disconnected?
The PCM is looking for the the “start/run” circuit to pulse which would be expected when the ignition key is turned on/off. But because of the switch fault this isn’t happening. When the battery is disconnected this provides the reset signal that the PATS system is looking for.