PCM - Engine Miss/Buck/Jerk/MIL ON
NO: 18-30-95GROUP: Vehicle Performance
DATE: Oct. 13, 1995
SUBJECT:
Rare Single Engine Miss, or
Diagnostic Trouble Code 25
66, or 70, or Minimum Air Flow
Test Failure
MODELS:
1996 (NS) Town & Country/Caravan/Voyager
SYMPTOM/CONDITION:
NOTE:
A VEHICLE MAY EXPERIENCE ANY ONE OR ALL OF THE FOLLOWING SYMPTOMS.
DRIVEABILITY
Some vehicles equipped with a 3.3L or 3.8L engine may experience a rare single engine miss, typically at highway speeds. The vehicle operator may describe it as a driveline buck or jerk and may think it is related to the transaxle. This condition is caused by a cam sensor unsync event and a Diagnostic Trouble Code (DTC) will not set.
ERRONEOUS ON BOARD DIAGNOSTIC (OBD) DTC'S
Some vehicles equipped with a 2.4L engine may experience an erroneous hex DTC 25, MAP Sensor Voltage Too High.
Some low mileage (less than 2000 miles) vehicles may experience an erroneous hex DTC 66, Upstream O2 Sensor Slow To Respond (2.4L/3.0L/3.3L/3.8L Engines).
Some higher mileage (approximately 70,000 miles plus) vehicles may experience an erroneous hex DTC 70, Catalytic Convertor Efficiency Failure, (2.4L/3.0L/3.3L/3.8L Engines).
SERVICE DIAGNOSTIC TESTS
The Minimum Airflow test will not fully close the Idle Air Control (IAC) motor and may be seen as a test failure by exceeding maximum allowable RPM specification (2.4L/3.0L/3.3L/3.8L Engines).
DIAGNOSIS:
Check the part number on the Powertrain Control Module (PCM), if it is not the same as the one specified below, perform the Repair Procedure.
Updated PCM Numbers:
4727166 PCM, 2.4L Engine 50 State
4727167 PCM, 3.0L Engine 50 State
4727168 PCM, 3.3L Engine 49 State
4727169 PCM, 3.3L Engine California
4727170 PCM, 3.8L Engine 50 State Front Wheel Drive
EQUIPMENT/PARTS REQUIRED:
1 CH6000 Scan Tool (DRB III)
1 CH7035 General Purpose Interface Bus Cable (GPIB)
1 CH7000 J1962 Cable
1 4669020 Label - Authorized Software Update
1 4275086 Label - Authorized Modification
NOTE:
THE MOPAR DIAGNOSTIC SYSTEM IS REQUIRED TO PERFORM THE FOLLOWING REPAIR AND THE SYSTEM MUST BE OPERATING WITH RELEASE 17 OR HIGHER AND TIL CD RELEASE 1091 OR HIGHER MUST BE INSTALLED.
REPAIR PROCEDURE:
This bulletin involves reprogramming (flashing) the PCM with new software (calibrations).
1. Connect the MDS (Mopar Diagnostic System) and DRB III (Scan Tool) to the vehicle and power them up.
2. Use the arrow keys and select # 2 MDS DIAGNOSTICS on the DRB III MAIN MENU Screen.
3. Use the arrow keys and select DIAGNOSTIC MENU on the MDS, then press NEXT MENU.
4. Use the arrow keys and select CONTROLLER PROGRAMMING on the MDS, then press NEXT MENU.
5. Use the arrow keys and select PROGRAM CONTROLLER PART on the MDS, then press NEXT MENU.
6. 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.
7. 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.
8. 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.
9. Type the necessary information on the "Authorized Software Update Label" and attach it to the PCM and cover the label with a clear plastic sticker.
10. Type the necessary information on the Authorized Modification Label and attach the label near the VECI Label.
POLICY: Reimbursable within the provisions of the warranty.
TIME ALLOWANCE:
Labor Operation No: 08-19-43-94 0.5 Hrs.
FAILURE CODE: FM - Flash Module