remove the light assy from the car.
The instrument cluster can be replaced. The connectors on the back of the instrument clusters are the same for all versions of that generation of the Ford Focus. There are however problems when doing this: -The odometer will show the miles from the old cluster. The milage is built in to the cluster, not the car. -Some panel lights (like the ABS light) may light up depending on your vehicle's options. It is sometimes possible (although usually relatively expensive) to have the cluster reprogrammed at a Ford dealership to correct these problems.
You have to remove the instrument cluster to get access to the bulbs.
The alternator is over or under charging.
NO. The battery light as you call it is actually the charging system light. If it is staying on the charging system is not working properly. More than likely the alternator has failed. It really has very little to do with the battery.
Check engine light : Gauge cluster without tachometer ( under the engine oil pressure gauge ) Gauge cluster with tachometer ( just to the left of the battery voltage gauge )
Unhook your negative battery cable, turn your light switch on, then turn it off and reconnect the battery. That should reset the computer.
To change the rear light cluster, first gain access to the boot, then remove the three plastic covers located directly behind cluster in boot these give you access to three 10mm nuts. To remove these nuts you will need a 10mm socket and a medium reach extension bar, remove all three nuts being careful not to drop them and the rear cluster will come away from body work then remove the lampholders to remove cluster completely. This is also how you would change a bulb in the rear cluster if you need to.
The check engine light on a 2002 Ford Focus can be reset by disconnecting the battery for 1 to 2 minutes. This resets the vehicle's computer and clears the light.
There is no reset for the charging system light. If it is on then you have a problem. More than likely the alternator is defective.
RKE, remote keyless entry. That message in the cluster means that either a remote is failing, or the battery in it is weak.
pull entire cluster out..its behind the circuit board of odometer
Remove the dash cluster to gain access to the back of the cluster to change the bulbs.