VISUAL INSPECTION
Most driveability problems in 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.
DIAGNOSTIC FORMATS
QUICK TEST and SYSTEM TESTS are diagnostic formats used to test and service EEC-V system. QUICK TEST allows technician to identify problems and retrieve diagnostic trouble codes. SYSTEM TESTS are used to check circuits, sensors and actuators.
Before starting any SYSTEM TEST, follow all steps under QUICK TEST to determine appropriate system test to perform. If vehicle passes QUICK TEST and no driveability symptoms or intermittent faults exist, EEC-V system is okay.
RETRIEVING DIAGNOSTIC TROUBLE CODES
Note. Self-diagnostic test procedures are for use with New Generation Star (NGS) scan tool. If a generic scan tool is used, ensure scan tool is certified to OBD-II standard.
Fault codes are retrieved from EEC-V system through Data Link Connector (DLC), located below instrument panel, left of steering wheel. Connect scan tool to data link connector. (Scheme 31) Start engine. Select DIAGNOSTIC TEST MODE and press trigger. If NO CODES RECEIVED/SYSTEM PASSED is displayed, all monitored systems are okay. If DTCs are present, see DIAGNOSTIC TROUBLE CODE IDENTIFICATION. See applicable DIAGNOSTIC TEST in appropriate SELF-DIAGNOSTICS article. If LINK MONITOR ERROR is displayed, check scan tool connection. Once all repairs have been completed, go to CLEARING DIAGNOSTIC TROUBLE CODES.
Scheme 31
DIAGNOSTIC TROUBLE CODES
During QUICK TEST, 3 types of Diagnostic Trouble Codes (DTCs) are retrieved: KOEO, KOER and Continuous Memory DTCs. See QUICK TEST for self-test procedures. DTCs may be cleared from PCM memory after DTCs have been recorded or fault has been repaired. See CLEARING DIAGNOSTIC TROUBLE CODES . If fault is still present after clearing DTCs, fault will reset.
KOEO & KOER ON-DEMAND SELF-TEST DTCs
Record DTCs in order received. These DTCs indicate current faults in system and should be serviced in order of appearance.
Note. If self-test will not activate or TOOL COMMUNICATION ERROR is received, follow instructions in scan tool manufacturer's manual.
DIAGNOSTIC MONITORING TEST RESULTS
Diagnostic Monitoring Test Results is the intermittent monitor system's technical data which displays system's thresholds and diagnostic results. Intermittent monitor system monitors O2 sensor, evaporative purge system, catalytic converter and EGR system. Technical data and thresholds have initial values. (Scheme 32) If test is not completed, initial values are displayed on scan tool. Initial values are shown in parentheses in MEAS, Minimum Threshold and Maximum Threshold columns. Catalytic converter will sometimes indicate an initial value even if test is completed. O2 sensor will not switch during this condition.
Scheme 32
CLEARING DIAGNOSTIC TROUBLE CODES
| CAUTION | DO NOT disconnect vehicle battery to clear DTCs. This will erase operating information from Keep-Alive Memory (KAM). To clear KAM, see RESETTING KEEP-ALIVE MEMORY (KAM) . |
QUICK TEST
Note. If vehicle has an emission compliance failure symptom, go to SYMPTOMS in TROUBLE SHOOTING - NO CODES article.
Quick Test is divided into 3 specialized test procedures that are functional tests of EEC-V system. All self-tests are completely menu driven using the New Generation Star (NGS) scan tool. The following procedures must be followed in sequence to avoid misdiagnosis
- «VISUAL CHECK»(ref-2836-S25793297622000041300000)
- «VEHICLE PREPARATION & EQUIPMENT HOOKUP»(ref-2836-S13149109062000041300000)
- «KOEO (KEY ON ENGINE OFF) ON-DEMAND SELF-TEST»(ref-2836-S39768197312000041300000)
- «KOER (KEY ON ENGINE RUNNING) ON-DEMAND SELF-TEST»(ref-2836-S09885420272000041300000)
- «CONTINUOUS MEMORY SELF-TEST»(ref-2836-S18930398722000041300000)
Complete QUICK TEST before performing any system tests. Record any DTCs retrieved. Service DTCs in the following order: KOEO DTCs, KOER DTCs and then Continuous Memory DTCs. After each service or repair procedure has been completed, always repeat QUICK TEST procedures to ensure all EEC-V systems are working properly and DTCs are no longer present.
Generic Scan Tool
Ensure scan tool meets or exceeds OBD-II standard. Follow scan tool manufacturer's operating instructions to hook up equipment and record DTCs.
New Generation STAR (NGS) Scan Tool
Turn ignition off. Ensure proper memory (EPROM) card is inserted into NGS scan tool. Connect service connectors of adapter cable to vehicle Data Link Connector (DLC) and the NGS scan tool. (Scheme 33) Connect NGS scan tool power supply cable to power and go to KOEO ON-DEMAND SELF-TEST.
Scheme 33
Performing Self-Test
To perform self-test, turn ignition off. Ensure test equipment is properly attached. Program scan tool using the following steps
- Select VEHICLE & ENGINE SELECTION menu.
- Select NEW VEHICLE, YEAR & MODEL.
- Select DIAGNOSTIC DATA LINK.
- Select PCM-POWERTRAIN CONTROL MODULE.
- Select DIAGNOSTIC TEST MODE.
- Select KOEO ON-DEMAND SELF-TEST.
- Turn ignition on.
- Follow operating instructions from scan tool menu.
- Record DTCs and perform appropriate system test. After test is complete, cycle ignition switch before performing other self-tests or driving vehicle.
To perform self-test, turn ignition off. Ensure test equipment is properly attached. Program scan tool using the following steps
- Select VEHICLE & ENGINE SELECTION menu.
- Select NEW VEHICLE, YEAR & MODEL.
- Select DIAGNOSTIC DATA LINK.
- Select PCM-POWERTRAIN CONTROL MODULE.
- Select DIAGNOSTIC TEST MODE.
- Select KOER ON-DEMAND SELF-TEST.
- Start engine and allow to idle.
- Follow operating instructions from scan tool menu.
- Record DTCs and perform appropriate system test. After test is complete, cycle ignition switch before performing other self-tests or driving vehicle.
To perform self-test, turn ignition off. Ensure test equipment is properly attached. Program scan tool using the following steps
- Select VEHICLE & ENGINE SELECTION menu.
- Select NEW VEHICLE, YEAR & MODEL.
- Select DIAGNOSTIC DATA LINK.
- Select PCM-POWERTRAIN CONTROL MODULE.
- Select DIAGNOSTIC TEST MODE.
- Select RETRIEVE/CLEAR CONTINUOUS DTCs.
- Turn ignition on.
- Follow operating instructions from scan tool menu.
- Record and DTCs that are present.
After test is complete, cycle ignition switch before performing other self-tests or driving vehicle.
ON-BOARD SYSTEM READINESS (OSR) TEST MODE
All OBD-II scan tools should be able to display the OSR test. The OSR will display monitors on the vehicle and status of all monitors; complete or not complete. See appropriate DRIVE CYCLES under ADDITIONAL SYSTEM FUNCTIONS . If not complete, the scan tool will display which monitor has not completed.
To enter OSR, turn ignition off. Ensure test equipment is properly attached. Program scan tool using the following steps
- Select VEHICLE & ENGINE SELECTION menu.
- Select NEW VEHICLE, YEAR & MODEL.
- Follow operating instructions from scan tool menu.
- Select GENERIC OBD-II FUNCTIONS. Press TEST button if monitors are not complete.
- Start engine and allow to idle.
- Select ON-BOARD SYSTEM READINESS.
OUTPUT TEST MODE
This mode allows a technician to energize and de-energize most of the system output actuators on command. After accessing OUTPUT TEST MODE, outputs and cooling fans can be turned on and off separately.
To access OUTPUT TEST MODE, turn ignition off. Ensure test equipment is properly attached. Program scan tool using the following steps
- Select VEHICLE & ENGINE SELECTION menu.
- Select NEW VEHICLE, YEAR & MODEL.
- Follow operating instructions from scan tool menu.
- Select DIAGNOSTIC DATA LINK.
- Select PCM-POWERTRAIN CONTROL MODULE.
- Select DIAGNOSTIC TEST MODE.
- Select ACTIVE COMMAND MODE.
- Select OUTPUT TEST MODE.
- Turn ignition on.
- Follow operating instructions from scan tool menu.
- Select START to turn outputs on.
- Select STOP to turn outputs off.
- Select either LOW SPEED FAN, HIGH SPEED FAN or ALL ON mode.