Light Spark Knock Timing Retard Feature (18-24-98)

WARNING: This page is about the Cherokee SE, 2D Utility, 2.5 P, 4WD, Automatic, which is a different variant/trim than selected.

Publication date: 1998-07-31
Reference number: 18-24-98

LIGHT SPARK KNOCK TIMING RETARD FEATURE

TECHNICAL SERVICE BULLETIN

Reference Number(s): 18-24-98, Date of Issue: July 31, 1998

LIGHT SPARK KNOCK TIMING RETARD FEATURE

Model(s): 1996-97 Dodge (AB) Ram Van

1996-97 Dodge (AN) Dakota

1996-97 Dodge (BR) Ram Truck, 1500, 2500, 3500

1996-97 Jeep (XJ) Cherokee

1996-97 Jeep (ZJ) Grand Cherokee

1996-97 Jeep (ZG) Grand Cherokee (International Markets)

Group: Vehicle Performance

Bulletin No.: 18-24-98

Date: July 31, 1998

NOTE: This information applies to vehicles equipped with a 2.5L, 4.0L, 3.9L, 5.2L and 5.9L light duty gasoline engines.

SYMPTOM/CONDITION

Some vehicles may exhibit LIGHT spark knock with a warm engine under load.

DISCUSSION

Determine when the customer exhibits this condition and verify it by driving the vehicle in similar conditions. If the vehicle exhibits high spark knock with a warm engine under load perform the flash update procedure. Once the flash procedure is completed, spark advance/retard may be adjusted.

NOTE: The DRB III MUST be operating at release 25.5 or higher.

Select DRB III stand alone, current model year diagnostics, engine, and miscellaneous. When in miscellaneous, spark advance will be available. Use the arrow keys to retard timing in 2° increments to a maximum of -4°. When the DRB III screen reads 0 the vehicle will be set at maximum advance and when at -4 it will be set at maximum retard.

NOTE: The ignition key MUST be cycled for the changes to take effect.

After performing the spark advance/retard feature, drive the vehicle to verify that the LIGHT spark knock is gone.

This feature will not compensate for heavy spark knock conditions. If heavy knock is experienced, further diagnosis and testing will be required.

NOTE: Whenever a Powertrain Control Module (PCM) is replaced due to failure, the software of the replacement controller should be verified for the latest revision level. Use the flash procedure to update replaced controllers as necessary.

PARTS INFORMATION

Part Number	Description	Qty.
CH6000	Scan Tool (DRB III)	1
CH7035	General Purpose Interface Bus Cable (GPIB)	1
CH7000/7001	J1962 Cable	1
04669020	Label - Authorized Software Update	1
04275086	Label - Authorized Modification	1

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 1165 or higher MUST be installed. The DRB III MUST be operating at Release 25.5 or higher.

REPAIR PROCEDURE

This bulletin involves selectively erasing and reprogramming the Powertrain Control Module (PCM) with new software.

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, then press NEXT MENU to begin programming.
If the PCM on the vehicle has already been updated or programmed, a NO UPDATES AVAILABLE message will be displayed. Check the part number of the PCM on the vehicle and compare it to the part number displayed. If the PCM has already been updated, then another condition exists that will require further diagnosis and repair.
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. See Fig 1 . 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 and attach the label near the VECI Label. See Fig 2 .

Fig 1: Authorized Software Update Label

Fig 2: Authorized Modification Label

WARRANTY INFORMATION

POLICY: Reimbursable within the provisions of the warranty.

Labor Operation No.: 08-19-41-96

Time Allowance: 0.5 hr.

Failure Code: FM - Flash Module