My mileage odometer reading does not display anymore for my pontiac aztec

Odometer
The IPC contains a season odometer and a trip odometer. Momentarily press the trip/reset switch on the IPC in order to toggle between the season odometer and the trip odometer. Press the trip/reset switch for greater than 2 seconds, while the trip odometer is displayed, in order to reset the trip odometer. The IPC displays the vehicle mileage and trip mileage as determined by the BCM. The BCM calculates the mileage based on the vehicle speed signal circuit from the PCM. The odometer will display 'error' if an internal IPC memory failure is detected or there is a loss of class 2 communication.

IPC - instrument panel cluster.

Replace the instrument panel cluster (IPC). Refer to Instrument Cluster Replacement .

Odometer
The odometer is an electronic digital display. Digits displayed are illuminated by the odometer backlight bulb. The odometer backlight bulb brightness is controlled by class 2 messages from the BCM to adjust the display for daylight and instrument panel dimming operation. The trip odometer and total odometer will show in this display area. The push button in the lower right side of the speedometer is used to toggle between the trip and total odometer readings. To reset the trip odometer, push and hold the button down for at least two seconds. The total odometer display has six digits with no decimal display. The trip odometer has four digits including a decimal point and indicates tenths of a mile or kilometer.
The body control module (BCM) stores the vehicle mileage. If the BCM fails, the cluster will display the last valid mileage that was sent before the BCM failed. For replacement of the BCM refer to the BCM section of this service manual. Replacement instrument clusters do not require odometer pre-setting before installation. If the instrument cluster is replaced, the mileage stored in the BCM will be sent to the new cluster via serial data, and shown in the odometer display.

Your best bet , take it to a qualified repair shop.

The IPC calculates the mileage based on the vehicle speed signal circuit from the powertrain control module (PCM). The odometer will display ERROR if an internal IPC memory malfunction is detected or there is a class 2 communication fault. The odometer displays either miles or kilometers as requested by the activation of the English/metric button on the driver information center (DIC). The associated indicator (km or MI) illuminates.
You probably have A class 2 serial data communication malfunction. All the Modules on your vehicle talk, share information on the data network an if something brings it down ,shorts it out, the vehicle will not start .
The data link connector (DLC) allows a scan tool to communicate with the class 2 serial data line. The DLC is a standardized 16 way connector located below the instrument panel and close to the steering column. Both the connector design and location are dictated by industry wide agreements. All DLCs are required to provide a power supply, hot at all times, to terminal 16. This circuit is used to power the scan tool. All DLCs supply a power ground at terminal 4 and a signal ground at terminal 5. The class 2 serial data circuit is provided at terminal 2 of the DLC.
You probably need to take this to a ASE certified repair shop or the a GM dealership ! Because if you are asking here you probably don't know about this stuff, an you sure don't have a factory scan tool to see which modules have DTC'S - diagnostic trouble codes stored .
You

The only way to rollback the odometer is to replace the cluster with lower miles. Unplugging would kill the whole cluster. The ECM keeps track of mileage also. You can have it read and see if it matches the odometer.

you cant its against the law to turn a odometer in any way shape or form sorry

just the odometer ? PRNDL ?
How To Fix PRNDL Odometer Display on GM Trucks

Your problem is not a fuse. The instrument illumination driver is dea in the cluster. Common with these vehicles. This type of repair can be done by automotive electrical specialty shops. We have repaired many of these units. if you need help with getting it repaired we are in Oshawa Ontario.

while you have the odometer reading current total mileage turn the key on while holding down the black button that switches from trip odometer to total mileage and you will see dashes where the odometer numbers are displayed. hold down the button until all the dashes disappear. then the display will read zeros when complete

try unplugging the battery for 15 minutes and that should reset the ecu, good chance this will fix it otherwise it sounds expensive and diagnostically not fun good luck let me know what you find

Erik
U.S. Army