Engine Controls - Delayed Return to Idle/DTC P0320 Set
01-002/991998-99 B-SERIES DELAYED RETURN TO IDLE AND/OR MIL "ON" DTC P0320
APPLICABLE MODELS:
All 1998-99 B-2500 with manual transmission (3.73 axle ratio only).
DESCRIPTION
Some vehicles may exhibit a delay at 1300-2000 engine rpms before returning to normal idle. The condition occurs on closed throttle deceleration in neutral or with the clutch depressed. There may also be illumination of the Malfunction Indicator Lamp (MIL) and Diagnostic Trouble Code (DTC) P0320 may be stored in memory. These conditions may be caused by the Powertrain Control Module (PCM).
Customers having this concern should have their vehicle repaired using the following procedure.
NOTE:
This modification will only correct this specific condition.
WARNING:
This modification is authorized only for the listed engine(s). Performing this modification on other engine calibrations is unauthorized and could create liability under applicable federal or local laws.
REPAIR PROCEDURE
NOTE::
This modification should only be performed if all other components related to idle control have been verified to be working properly. (See diagnostic index in section 01 of Workshop Manual).
1. Verify customer complaint.
2. Select the appropriate card (SST part number 49G0-88-016) and reprogram the PCM using one of the following calibrations. Refer to the "IN-Car Flash Procedure".
^ 9B1M-AB (Federal)
^ 9B1M-BA (California)
PCM replacement is not authorized by this Service Bulletin. Refer to section (01) of the Workshop Manual for diagnostic procedures if PCM hardware concerns exist.
3. Verify repair.
WARRANTY INFORMATION
This information applies to verified customer complaints on vehicles covered under normal warranty. Refer to the SRT microfiche for warranty term information.
B-SERIES IN-CAR FLASH CABLE PROCEDURE
SET-UP PROCEDURE
1. Insert the In-Car Flash Cable (SST 49G0-88-0110) into the NGS tester and connect to the vehicle's data link connector.
CAUTION:
Be sure the NGS is unplugged before inserting or removing cards.
NOTE:
Although similar in appearance, this cable is not the same as the diagnostic cable supplied with the NGS tester.
REPROGRAMMING PROCEDURE
1. Select "PCM Reprogramming" on the NGS tester and press Trigger.
2. Follow the prompts on the NGS tester to complete reprogramming.
NOTE:
Ignore any DTCs displayed during reprogramming and press Trigger to continue.
If you receive the message, "VEHICLE CURRENTLY CONTAINS THIS CALIBRATION" it has already been reprogrammed.
^ If you receive the message,"VEHICLE CONTAINS CORRECT HARDWARE, SOFTWARE FOR DIFFERENT VEHICLE-VERIFY VIN/QUALIFIER IS CORRECT" press Trigger to continue.
3. KOEO (Key On Engine Off) test will run automatically after reprogramming is complete and will display any trouble codes found.
4. Start the engine and let it idle for 5 seconds and verify that the MIL is not on.
5. List the date, dealer number, calibration code and Service Bulletin number on an "Authorized Modification" label (P/N 9999-95-AMDC-97) and install it on the radiator support. Labels are available via M-NET.
NOTE:
This label will inform future technicians of the updated PCM calibration.
Disclaimer