Engine Controls - Rough Idle Following A Hot Soak: Overview
NUMBER: 18-039-03GROUP: Vehicle Performance
DATE: November 14, 2003
THIS BULLETIN is BEING PROVIDED IN ADVANCE. THE SOFTWARE WILL BE AVAILABLE ON TechCONNECT ON OR AFTER DECEMBER 09, 2003.
SUBJECT:
4.0L Rough Idle Due To High Ambient or Hot Soak Temperatures
OVERVIEW:
This bulletin involves selectively erasing and reprogramming the Powertrain Control Module (PCM) with new software.
MODELS:
2000 - 2001 (XJ) Cherokee (Domestic Market)
NOTE:
This bulletin applies to all 2001 model year XJ vehicles equipped with a 4.0L engine, automatic transmission, and a 50 state emissions package (sales code NAS) If the vehicle is a 2000 model year 4.0L XJ this bulletin applies only if the vehicle is equipped with an automatic transmission and has a California level emissions package (sales code NAE).
SYMPTOM/CONDITION:
The customer may describe a 20 to 30 second rough idle following the restart of a heat soaked engine. This condition may be most noticeable when the engine is restarted following a 10 to 20 minute heat soak in hot ambient conditions of approximately 32°C (90°F) or higher. This condition may be consistent with short city stop-and-go driving trips and can be aggravated by the use of fuel with high ethanol content.
The new software lowers the temperature threshold used to determine when the engine cooling fans are turned on. The cooling fans will cycle on more often.
DIAGNOSIS:
Using a Scan Tool (DRBIII(R)) with the appropriate Diagnostic Procedures Manual, verify all engine systems are functioning as designed. If DTCs are present record them on the repair order and repair as necessary before proceeding further with this bulletin.
Verify that Service Bulletin 18-031-03 has been performed.
If the customer describes the Symptom/Condition, perform the Repair Procedure.
PARTS REQUIRED:
SPECIAL TOOLS/EQUIPMENT REQUIRED:
NOTE:
An updated J1962 cable has been released. This cable has a red colored connector at the DRBIII(R) connection. Use this cable whenever a flash is being performed.
POLICY:
Reimbursable within the provisions of the warranty.
TIME ALLOWANCE:
FAILURE CODE: