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Introduction

In this guide, you will be learning how to replace the CMOS Battery in a Dell Latitude 7400. The CMOS battery powers the motherboard's Real-Time-Clock (RTC) and the CMOS chip. This stores the system's date and time information when the computer is powered off. If your computer starts to display the incorrect date/time, or if custom settings in your BIOS are lost when you turn it off, it may be time to replace the CMOS Battery. This guide will walk you through step by step on replacing this battery.

What you need

Step 1 Battery

Dell Latitude 7400 CMOS Battery Replacement, Battery: step 1, image 1 of 3

Dell Latitude 7400 CMOS Battery Replacement, Battery: step 1, image 2 of 3

Dell Latitude 7400 CMOS Battery Replacement, Battery: step 1, image 3 of 3

Lay the laptop on a flat hard surface facing downward.
Use a Phillips #0 screwdriver to remove the eight 3 mm screws that secure the lower case.
Lift the lower case off and set that aside.

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Step 2

Dell Latitude 7400 CMOS Battery Replacement: step 2, image 3 of 3

Use a Phillips #0 screwdriver to loosen the two 3 mm captive screws that secure the battery.
The screws will not remove completely, so just loosen them enough to lift battery.
Gently grip the battery connector loop and lift it to disconnect the battery connector.
Lift the battery up and out.

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Step 3 CMOS Battery

Dell Latitude 7400 CMOS Battery Replacement, CMOS Battery: step 3, image 1 of 2

Dell Latitude 7400 CMOS Battery Replacement, CMOS Battery: step 3, image 2 of 2

Lift the black locking flap that secures the I/O board ribbon cable.
Disconnect the ribbon cable.

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Step 4

Gently pull on the JST connector to disconnect it and remove the CMOS battery completely.

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Conclusion

To reassemble your device, follow the above steps in reverse order.
Take your e-waste to an R2 or e-Stewards certified recycler.
Repair didn’t go as planned? Try some basic troubleshooting or ask our Answers community for help.

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