Thank you for the added Info:
The SERVICE (Wrench) telltale is pulled to ground by the PCM. When the lamp is pulled to ground, current from the ignition circuit flows through the telltale lamp, allowing it to come On. The PCM will turn the SERVICE (Wrench) telltale On for all non-emission related diagnostic trouble codes (DTCs ) that require that a telltale be turned On (some DTCs do not turn on a telltale but are stored to aid in diagnosis).The SERVICE (Wrench) telltale will also be turned On if the ABS control module has detected a fault in its own warning indicator system. If the ABS system cannot turn on its own telltale, a message will be sent to the PCM through the class 2 data bus (circuit 1807) to turn on the SERVICE (Wrench) telltale.
Reset is done by Dealer Scan Tool, but will come back on if problem is not Repaired:
SERVICE (WRENCH) TELLTALE RESET PROCEDURE To reset the Service (Wrench) telltale all codes must be cleared including Powertrain Control Module (PCM) , Body Control Module (BCM) and Antilock Braking System (ABS) Codes.Clearing diagnostic trouble codes is accomplished by choosing the "Clearing Trouble Codes" option in the Scan tool DTC menu. Disconnecting the battery for 60 seconds (and in some cases longer) will clear DTCs, active and history from PCM memory. Failure Record information will also be cleared.