Engine Controls - Self-Diagnostics - Introduction: Diagnosis Mitsubishi Mirage V

SYSTEM DIAGNOSIS

Note. Some models may use an Engine Control Module (ECM) or a Powertrain Control Module (PCM). In testing procedures and illustrations, the terms may be used interchangeably. For correct application, see WIRING DIAGRAMS article. Engine Control Module/Powertrain Control Module (ECM/PCM) diagnostic memory is retained by direct power supply from battery. Memory is not erased by turning off ignition, but it will be erased if battery or ECM/PCM is disconnected.

Note. Some ECM/PCM data and tests are only accessible with manufacturer's MUT-II scan tool. Those tests are not covered in this article. All codes that turn on MIL can be retrieved with compatible generic scan tool. Those tests are covered in this article.

ECM/PCM includes On Board Diagnostics II (OBD-II) software designed to monitor emissions control system over the life of the vehicle. On OBD-II, the Malfunction Indicator Light (MIL) (Service Engine Soon light) will only illuminate for emissions system related faults. Most of these faults will not cause driveability problems and would go unnoticed by the driver were it not for the MIL. When MIL illuminates, a Diagnostic Trouble Code (DTC) will be stored. The ECM/PCM may also store DTCs that do not illuminate the MIL. These may be pending codes, or are not emissions system related. On all models, DTCs may be retrieved using a MUT-II or a compatible generic scan tool. On Eclipse 2.0L non-turbo, the MIL can also be used. See ENTERING ON-BOARD DIAGNOSTICS .

ECM/PCM monitors several different engine control system circuits. If an abnormal input signal occurs, a Diagnostic Trouble Code (DTC) is stored in ECM/PCM memory as either a pending or mature code. A specific DTC indicates a particular system failure, but does not indicate that cause of failure is necessarily within system. Most faults require that the malfunction be detected during 2 different trips before the MIL is illuminated. The first occurrence of the fault will store a pending DTC. The second occurrence of the fault will set a DTC and illuminate the MIL. Faults that will cause catalytic converter damage will turn on the MIL when the malfunction is first detected. In the case of severe misfire, MIL will flash on and off as long as misfire persists.

For certain system or component failures, ECM/PCM will enter fail-safe function (limp home mode). In fail-safe mode, ECM/PCM will substitute default values for the faulty component or system.

Each circuit or system monitored by ECM/PCM has particular engine and driving conditions that must be met before ECM/PCM will monitor it. These conditions are the code set criteria. Due to differences in code set criteria, some circuits or systems are monitored almost continuously while others may not be monitored at all during a particular drive cycle. After a repair, it is necessary to run the vehicle under conditions that meet code set criteria in order to verify the repair. To verify a misfire or fuel trim repair, it is also necessary to operate the vehicle in conditions similar (engine speed, engine load, engine temperature, etc.) to those when the misfire occurred. These conditions are recorded as freeze frame data. Check freeze frame data before erasing DTCs, as freeze frame data will also be erased.

Readiness Test Status

During different parameters of engine operation, the ECM/PCM monitors and runs tests on various inputs, outputs and system functions. There are 6 monitors. oNE MONITOR (Other Monitor) passively monitors for shorts, grounds and out of range parameters. It runs nearly continuously. The other 5 monitors actively test different systems and will only run when very specific engine operating conditions have been met. So those monitors may or may not run during any given drive cycle. These 5 monitors have a system readiness test to show whether the particular monitor has been run or not. Other Monitor does not show up in system readiness test list because it always runs.

When ECM/PCM DTCs are cleared, readiness test status is set to incomplete. To complete readiness test status, OBD-II drive cycle related to all on-board diagnostic items should be carried out. If vehicle is normal, readiness test status will complete by carrying out OBD-II drive cycle once. If ECM/PCM detects a malfunction, OBD-II drive cycle must be carried out again before readiness test status will complete. Once readiness test status is complete, ECM/PCM can be checked for DTCs.

VISUAL INSPECTION

Most driveability problems in the engine control system result from faulty wiring, poor electrical connections or leaking air and vacuum hose connections. To avoid unnecessary component testing, perform a visual inspection before beginning self-diagnostic tests.

ENTERING ON-BOARD DIAGNOSTICS

Note. DO NOT skip any steps in self-diagnostic tests or incorrect diagnosis may result. Ensure self-diagnostic test applies to vehicle being tested.

On Eclipse 2.0L non-turbo, DTCs may be retrieved using Malfunction Indicator Light (MIL) or a scan tool. On all other models, DTCs may be retrieved by using a scan tool only. Proceed to appropriate DTC retrieval method.

Using Scan Tool

1. Refer to manufacturer's operation manual for instructions in use of scan tool. Before entering on-board diagnostics, see «SERVICE PRECAUTIONS»(ref-91119-S33535881952001030200000) . Locate OBD-II Data Link Connector (OBD-II DLC) under instrument panel, near steering column.
2. Turn ignition switch to OFF position. Connect scan tool to DLC. Turn ignition switch to ON position. Read and record scan tool self-diagnostic output. Proceed to «TROUBLE CODE DEFINITIONS»(ref-91119-S31367277032001030200000) .

TROUBLE CODE DEFINITIONS

When DTC is obtained, refer to DTC index and appropriate test procedure in appropriate SELF-DIAGNOSTICS article.

SYSTEM READINESS TEST PROCEDURE

Note. This procedure applies to Eclipse 2.0L non-turbo only. This is an EVAP leak detection test. Use this procedure only if directed here from self-diagnostic tests.

1. Using scan tool, clear DTCs. Keep scan tool connected to Data Link Connector (DLC). Go to next step.
2. To run the test: Vehicle must be started cold. Battery temperature must be 40-89°F (4-31°C). Engine coolant temperature must be within 10°F (5.6°C) of battery temperature. Battery voltage must not drop below 10 volts during cranking or test will not run. Low fuel warning light must be off. MAP sensor reading is 11 psi (75 kPa). Engine must not stall during test. Following DTCs must not be set: DTCs P0107, P0108, P0117, P0118, P0121, P0340, P0443, P0605, P1296, P1492, P1493 and MIL 44.
3. Within 40 seconds of starting engine, a light cycling tapping should be felt in the Leak Detection Pump (LDP) as the LDP activates. If LDP activates, go to next step. If LDP does not activate, check for DTCs. If no DTCs are set, confirm all required monitor conditions are met. If so, disconnect PCM connector A-107 for about 2 minutes. Then reconnect PCM connector and start test over.
4. Using scan tool, observe system readiness test status for EVAP and go to next step.
5. Drive vehicle on a level surface at steady speed of 56-72 MPH. This can include slowing and stopping. It will take 10 minutes or less to complete readiness test. Test is complete when EVAP CMP is displayed on scan tool. Repair is verified. If test does not complete, either conditions for monitor to run were not met or repair was not complete.

Note. If system readiness test must be run again, let engine cool down, or trick PCM into thinking engine temperature is within 10°F (5.6°C) of battery temperature by substituting appropriate resistor between Engine Coolant Temperature (ECT) sensor connector terminals. If scan tool says battery temperature reading is 70-88°F (21-31°C), use 10 k/ohm (1/2 W) resistor. If battery temperature reading is 52-70°F (12-21°C), use 15 k/ohm (1/2 W) resistor. If battery temperature reading is 41-55°F (5-13°C), use 22 k/ohm (1/2 W) resistor.