I hope they didn't do this:
NO: 18-28-97
SUBJECT: Premium Unleaded/Regular Unleaded Fuel Selection
DATE: Aug. 29, 1997
NOTE: THIS INFORMATION APPLIES TO 5.9L ENGINES.
DISCUSSION:
The 1998 5.9L Grand Cherokee was designed to use Premium Unleaded fuel. This selection was made to maximize the horsepower and torque from the engine. Some customers may prefer using Regular Unleaded fuel due to cost factors associated with using premium. If a customer prefers using regular fuel, the software of the powertrain control module will require flash programming to prevent driveability concerns. The regular fuel calibration will reduce engine horsepower and torque.
This flash program procedure will allow a technician to select either a premium fuel calibration or a regular fuel calibration. These calibrations can be re-flashed from one to the other at any time.
NOTE: THIS CALIBRATION SHOULD BE CHOSEN BY THE CUSTOMER.
EQUIPMENT/PARTS REQUIRED:
QuantityPart No.Description1CH6000Scan Tool (DRB III)1CH7035General Purpose Interface Bus Cable (GPIB)1CH7000/7001J1962 Cable104669020Label - Authorized Software Update104275086Label - Authorized Modification
NOTE: THE MDS AND DRB III ARE REQUIRED TO PERFORM THIS REPAIR AND THE SYSTEM MUST BE OPERATING WITH RELEASE 21 OR HIGHER AND TIL CD RELEASE 1140 OR HIGHER MUST BE INSTALLED.
PROCEDURE:
This procedure involves selectively erasing and reprogramming the Powertrain Control Module (PCM) with new software (calibration changes).
- Connect the MDS (Mopar Diagnostic System) and DRB III (Scan Tool) to the vehicle and power them up.
- Use the arrow keys and select #2 MDS DIAGNOSTICS on the DRB III MAIN MENU Screen.
- Use the arrow keys and select DIAGNOSTIC MENU on the MDS, then press NEXT MENU.
- Use the arrow keys and select VEHICLE CONTROLLER PROGRAMMING on the MDS, then press NEXT MENU.
- Use the arrow keys and select PROGRAMMING OF ALL OTHER CONTROLLERS USING MDS & DRB III on the MDS, then press NEXT MENU.
- Follow the steps presented on the MDS and DRB III which will allow the DRB III to obtain the current part number of the PCM.
- The MDS will display the part number of the PCM on the vehicle and the appropriate replacement part number(s). Select the appropriate calibration either for Regular fuel or Premium fuel, then press NEXT MENU to begin programming.
- The MDS and DRB III will prompt for any operator action needed during the remainder of the programming process. NOTE: THE FOLLOWING STEPS ARE REQUIRED BY LAW.
- Type the necessary information on the "Authorized Software Update Label" p/n 04669020. Attach the label to the PCM and cover the label with the clear plastic overlay.
- Type the necessary information on the "Authorized Modification Label" p/n 04275086. Attach the label near the VECI Label.
POLICY: Information Only