1998 Malibu Instrument light not working

Make sure your ignition switch is working first (does everything light up and working with the key in "ON" position) then try ACC position, does the radio work? If all that checks out then it would be the stepper motors on the instrument cluster are bad, there are several repair kits available pretty cheap since they are a common problem

Replacing a fuel pump has nothing to do with instrument cluster lights or the clock staying on. Unless you shorted wires , did you disconnect the negative battery cable before hand ?
The body control module (BCM) performs the following functions:
• A/C compressor request
• A/C cooling fan
• Exterior and interior lighting control
- Daytime running lights (DRL)
- Automatic lighting control
- Fog lamps
- Interior lighting
• Battery rundown
• Chime
• Gauge control
• Instrument cluster indicator control
• Fuel gauge control
• Temperature gauge control
• Theft deterrent
Interpreting all of the driver warnings sent by the control modules on the class 2 serial data line
Sending the information to the instrument cluster in the form of a SPI serial data bus message
The following list of messages are sent by the BCM to the instrument cluster:
• Fuel gauge position
• Temperature gauge position
• Oil pressure
• Low engine coolant
• Check oil
• Volts
• ABS
• High beam
• Low fuel
• High temperature
• Washer fluid level low
• CRUISE
• BRAKE
• SERVICE VEHICLE SOON
• Door ajar
• Seat belt
• THEFT SYSTEM
• PRNDL
Check the fuel level sensor wires , the fuel level sensor is a input to the BCM .

There is a diagnostic procedure in the factory service repair manual for engine light lit ,no codes . Did you take it to ford dealer ? MIL - is referring to check engine , service engine soon etc...

• MIL always on when engine is running (no DTCs):
• MIL circuits

• For Focus, Mustang, Town Car, Continental, LS6/LS8, Escape, Windstar, F-150, Expedition and Navigator/Blackwood:
• Instrument Cluster, Section 413-01 of the Workshop Manual.
• All Others:
• GO to NB1

SERVICE ENGINE SOON indicator After the engine is started, the SERVICE ENGINE SOON indicator will prove out for a duration of three seconds. If the instrument cluster does not receive a message from the PCM within five seconds, the instrument cluster will illuminate the SERVICE ENGINE SOON indicator and log a diagnostic trouble code (DTC).

• An indicator is inoperative/always on - SERVICE ENGINE SOON

• Circuitry.
• Bulb.
• Instrument cluster.
• PCM.

• GO to Pinpoint Test P .

PINPOINT TEST P: AN INDICATOR IS INOPERATIVE/ALWAYS ON - SERVICE ENGINE SOON CONDITIONS DETAILS/RESULTS/ACTIONS P1 CARRY OUT THE INSTRUMENT CLUSTER SERVICE ENGINE SOON INDICATOR ACTIVE COMMAND Trigger the HEC active command MIL.

• Did the SERVICE ENGINE SOON indicator illuminate?

Yes REFER to Powertrain Control/Emissions Diagnosis (PC/ED) manual.

No INSTALL a new instrument cluster; REFER to Instrument Cluster . CLEAR the DTCs. REPEAT the self-test.

2007 Chevy Malibu Owner's Manual
Looks like it is in the fuse box by the instrument panel. You will find the diagram on page 448.

The Tail lights and Instrument lights are usually on the same circuit so both will go out if the fuse for the circuit blows. Check for a blown fuse for this circuit and replace if out. If fuse continues to fail, check the tail light or side globes for a faulty globe and replace if necessary. Also check for any chafed wires that could be shorting to the body causing the fuse to blow.

try the fuses and relay switches. get a chiltons manual if you dont have a diagram for the fuses and relays from an auto parts store

check grounds wires

see if you have power going to the break light. it may be bad bolb.or broken wires

The instrument cluster operates independantly of the lighting for them. You could possibly have a fuse somewhere that has blown causing all gauges to stop, or it could potentially be that the cluster itself is bad and needs replaced or this could be a sign of a wireing harness failure of the instrument cluster. I'm afraid your best bet is to take it in and have it looked at by someone trained in dealing with those parts of the system.