OBD II - MIL ON With No DTC's Set During I/M Check
No.: TSB-02-13-005DATE: February, 2002
MODEL: See Below
SUBJECT:
1996 MODEL OBD-II MIL STATUS "ON" AND I/M PROGRAM TEST FAILURES
PURPOSE
During a check of the On-Board Diagnostic (OBD) system on some model year 1996 Mitsubishi vehicles, it was found that the malfunction indicator lamp (MIL) is commanded "ON" even though there may be no diagnostic trouble codes (DTC's) stored at that time. This error was discovered during OBD-II inspection maintenance (I/M) checks involving a small number of vehicles. Monitoring of the vehicle emissions control systems and all other man This error does not affect the effective operation of the OBD-II system during actual driving conditions. Monitoring of the vehicle emissions control systems and all other mandated functions (including triggering the MIL "ON" if a DTC is stored) remain fully operational. The foregoing issue only arises during I/M type checks of the system.
After investigating and confirming this error, Mitsubishi Motors notified appropriate state and federal officials of this issue. Please be advised that: (1) this programming scheme will not affect the OBD-II function to detect emission failures in the subject vehicle's emission system - all systems will continue to accurately monitor and detect any problems or faults in the emission control systems of affected vehicles; (2) the ECU's in the affected vehicles cannot be reprogrammed through reflashing; and (3) the number of affected vehicles continues to decline as the vehicle population is replaced.
This TECHNICAL SERVICE BULLETIN provides a procedure, shown on the flow chart, that confirms the OBD-II systems for model year 1996 vehicles are operating correctly.
AFFECTED VEHICLES
NOTE:
Most early model year 1996 models and some late model year 1996 3000GT models are affected.
1996 3000GT/Spyder 3.0L SOHC, 3.0L DOHC, 3.0L DOHC Turbo
1996 Diamante 3.0L SOHC
1996 Eclipse/Eclipse Spyder, 2.0L Turbo
1996 Expo/Expo LRV 1.8L & 2.4L
1996 Galant 2.4L
1996 Mirage 1.5L & 1.8L
1996 Montero 3.0L SOHC & 3.0L DOHC
1996 Mighty Max Pickup Truck 2.4L
PROCEDURE
OBD-II Systems for the model year 1996 vehicles were developed at an early stage of Mitsubishi's OBD development. The following early-production OBD-II systems issues have occurred, and countermeasures taken.
1. Difficulty in completing Readiness Codes for catalyst and evaporative leak monitors. To ensure that Readiness Codes are properly completed, strictly follow the drive cycle procedures detailed in TSB-00-13-005.
(Current EPA guidelines allow two incomplete Readiness Codes for 1996MY through 2000MY vehicles during a state I/M OBD-II inspection, so this would generally not result in an inspection failure.)
2. Readiness Codes being cleared on V6 models when all codes are set. followed by an ignition key off.
When checking for Readiness Codes (noted in TSB-00-13-005), connect OBD scan tool to the vehicle prior to turning the ignition off.
3. MIL status "commanded ON", regardless of DTC setting.
After confirming that all Readiness Codes are complete and there are no stored DTCs, it can be concluded that the vehicle's OBD-II system is functioning properly.
SUPPLEMENTAL INFORMATION
Refer to the attachment, "OBD-I/M Test Procedure" flow chart, for the OBD-II functional inspection procedure generally used by state I/M stations.
WARRANTY INFORMATION
Mitsubishi Motors will continue to honor warranty claims submitted for repairs related to this Technical Service Bulletin as long as the vehicle still has warranty coverage. For any questions regarding warranty coverage or reimbursement, contact the Warranty Hotline, 1-800-380-2324.