Diagnostic Procedure
Refer to ENTERING ON-BOARD DIAGNOSTICS in this article to retrieve fault codes. If no fault codes are present and/or DRB-II (C-4805) is being used, but vehicle still displays one of the following conditions, go to appropriate test.
- No start condition or engine will not continue to run after start. Go to No Start Test 1 (NS-1) chart for your engine.
- Engine runs but has performance problems. Go to Driveability Test 1 (DR-1) chart for your engine.
NOTE:
When using trouble shooting charts for diagnosis, DO NOT
skip any steps in chart as incorrect diagnosis will result.
Before proceeding with diagnosis, the following precautions must be followed:
- Vehicle must have a fully charged battery and no charging system problems.
- When probing connectors, probe connector from pin side. DO NOT backprobe connector.
- When performing electrical tests, be careful not to cause any short circuits. This will set more fault codes, making diagnosis of original problem more difficult.
- DO NOT use a test light in place of a voltmeter.
- When checking for spark, ensure coil wire is no more than 1/4" from ground. If wire is farther away from ground, damage to vehicle electronics may result.
- DO NOT prolong testing of fuel injectors as engine may hydrostatically lock.
- Always repair lowest fault number (CHECK ENGINE light) or first fault displayed (DRB-II) first.