* Resetting the PCM (Powertrain Control Module): This is the main computer that controls the engine, transmission, and other drivetrain systems. There's no "reset" button. Disconnecting the battery's negative terminal for about 30 minutes is the closest equivalent. This clears the short-term memory and can sometimes help with minor issues like erratic idle or trouble codes. Caution: This will erase the radio presets and possibly some other settings.
* Resetting the Electronic Control Unit (ECU) for other systems: The Cherokee has various other ECUs (like for the body control module, ABS, etc.). Disconnecting the battery negative terminal generally affects them all. However, some specialized tools may be needed for specific ECU resets.
* Clearing trouble codes: If you're dealing with a check engine light, you need to clear the diagnostic trouble codes (DTCs). This requires a scan tool (OBD-II scanner) that can communicate with the PCM. You cannot clear these simply by disconnecting the battery.
* Resetting the radio: If you're locked out of your radio, you might need to consult your owner's manual for the specific reset procedure. This typically involves a sequence of button presses.
To disconnect the battery (for PCM reset):
1. Locate the negative (-) battery terminal. It's usually marked with a "-" symbol.
2. Use a wrench to loosen the terminal clamp.
3. Remove the clamp.
4. Wait for at least 30 minutes. Longer won't hurt.
5. Reconnect the clamp.
6. Start the vehicle and see if the issue is resolved.
Important Note: If you're experiencing persistent problems, simply disconnecting the battery might not solve the underlying issue. A proper diagnosis using a scan tool is often necessary to identify and fix the root cause. A qualified mechanic can help you with this if you are not comfortable performing diagnostics yourself. Never work on your vehicle's electrical system without disconnecting the battery first as a safety precaution.
