The OBD System Check determines:
WARNING: This page does not describe the selected car, but rather 14 other vehicles, including the 1998 GMC Savana Special, 1998 GMC Savana Camper Special, 1998 GMC Savana, 1998 Chevrolet RV Cutaway, and 1998 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
- If Malfunction Indicator Light (MIL) works.
- If VCM is operating and can recognize a fault.
- If any codes are stored.
OBD system check is the starting point for utilizing the self-diagnostic system for determining computer-related problems. After performing necessary tests as described in diagnostic system check, if no codes are indicated and driveability problems still exist, see appropriate TESTS W/O CODES article in ENGINE PERFORMANCE:
- TESTS W/O CODES - (4.3L 1997).
- TESTS W/O CODES - (4.3L 1998).
- TESTS W/O CODES - (5.0L 1997).
- TESTS W/O CODES - (5.0L 1998).
- TESTS W/O CODES - (5.7L 1997).
- TESTS W/O CODES - (5.7L 1998).
- TESTS W/O CODES - (7.4L 1997).
- TESTS W/O CODES
- (7.4L 1998).NOTE: The following steps should be performed first to reduce diagnostic time and prevent replacement of good parts.
- Turn ignition off. Connect scan tool and follow scan tool manufacturer's instructions to proceed with test. Turn ignition on. If MIL is on, go to next step. If MIL is off, see MALFUNCTION INDICATOR LIGHT (MIL) under BASIC TESTING article in ENGINE PERFORMANCE:
- BASIC TESTING - (4.3L 1997).
- BASIC TESTING - (4.3L 1998).
- BASIC TESTING - (5.0L 1997).
- BASIC TESTING - (5.0L 1998).
- BASIC TESTING - (5.7L 1997).
- BASIC TESTING - (5.7L 1998).
- BASIC TESTING - (7.4L 1997).
- BASIC TESTING - (7.4L 1998).
- Turn ignition on, with engine off. If scan tool displays VCM data, go to next step. If scan tool does not display VCM data, go to DLC DIAGNOSIS OR NO SCAN TOOL DATA under BASIC TESTING article in ENGINE PERFORMANCE.
- Using scan tool, check for any DTCs stored in Last Test Failed, Failed This Ignition, MIL Request or History. If any DTC's are stored, using scan tool, save freeze frame and failure record information using "Capture Info" feature, then diagnose DTC. If DTC is not stored, go to next step.
- Attempt to start engine. If engine starts and runs, go to next step. If engine does not start or starts and dies, go to NO-START DIAGNOSIS under BASIC TESTING article in ENGINE PERFORMANCE.
- Compare scan tool data with specific component values. If values are not within specified range, check related circuit or component(s). See SYSTEM/COMPONENT TESTS article in ENGINE PERFORMANCE. If component is okay, see TESTS W/O CODES article in ENGINE PERFORMANCE:
- SYSTEM/COMPONENT TESTS - (4.3L 1997).
- SYSTEM/COMPONENT TESTS - (4.3L 1998).
- SYSTEM/COMPONENT TESTS - (5.0L 1997).
- SYSTEM/COMPONENT TESTS - (5.0L 1998).
- SYSTEM/COMPONENT TESTS - (5.7L 1997).
- SYSTEM/COMPONENT TESTS - (5.7L 1998).
- SYSTEM/COMPONENT TESTS - (7.4L 1997).
- SYSTEM/COMPONENT TESTS - (7.4L 1998).