Things you need to know before disconnecting your car battery

Disconnecting a car battery for any reason, may cause unexpected things to happen. Among the things that you could expect includes: 

 1. Starting problems 
 2. Drivability issues 
 3. Loss of air conditioning 
 4. Power accessory functions (door windows, seats, sunroof) 
 5. False warning lights 
 6. Damage to electronic modules 

So, disconnecting the car battery to reset the (PCM) on late model vehicles; can do more than just erase the keep alive memory. It can also erase vital learned information that is; absolutely necessary for other modules to function normally. 

It all depends on; The Year, Make And Model Of Your Vehicle. 
 1. Battery voltage MUST be maintained to the (PCM) and other modules; while the battery is disconnected.
 2. NEVER: disconnect the car battery; while the engine is running or the ignition key is turned on. 
 3. Disconnecting the car battery can create a; high voltage spike in the electrical system. Consequently, damaging electronic modules. 

Learn What Can Go Wrong; Before You Disconnect Your Car Battery 

Disconnecting your car battery without proper monitoring of its voltage may cause the engine to run poorly. Firstly, high/low voltage could cause the air/fuel mixture to become either too rich or too lean; which could cause your transmission to feel slightly abnormal, at least until the PCM can relearn the shift adjustments. The affected module could potentially prevent the ABS or airbag systems from working. 

Secondly, your climate control module may also be affected. So, on some vehicles, that means the A/C will not work until the module is programmed with the correct settings. It also, resets the body control module (BCM). This can mess up the operation of power accessories including power windows, memory seats; power sunroof or electronic suspension settings. It may, reset or disable the anti-theft system too.  

A disabled anti-theft system may cause your car engine to crank but not necessarily to start. This is because, the anti-theft system thinks; somebody is trying to steal the vehicle. 

Thirdly, you might also loss power window and/or power sunroof position settings as well as steering angle sensor settings. The steering angle sensor will have to undergo a relearn procedure; following the disconnection of the battery. Replacing the car battery on some vehicles requires entering the new battery info into the (PCM) with a scan tool. This is necessary because; the vehicle’s charging system is programmed to gradually increase the charging rate, as the battery ages.  

Finally, the most common scenario following a disconnection to the battery causes a loss of channel settings on electronic radio and digital clock. 

We understand the urge to D.I.Y and experiment a lot of things particularly when we’re stuck at home during this extended Movement Control Order but at Bateriku.com, you’re just a few clicks away to get advice on all things related to your car batteries. Stay safe at home and be sure your car is safe and well too with Bateriku.com. 


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