Diagnostic Procedure

Refer to ENTERING ON-BOARD DIAGNOSTICS to retrieve fault codes. If fault codes are NOT present and/or DRB-II (Diagnostic Readout Box-II) is used, proceed to one of the following tests:

• Go to NO START TEST 1 (NS-1) chart if a no-start condition exists or engine stalls after start-up. Perform indicated VERIFICATION PROCEDURE chart after repairs. Ensure charts apply to engine being tested.
• Go to DRIVEABILITY TEST 1 (DR-1) chart if engine runs but has performance problems. Perform indicated VERIFICATION PROCEDURE chart after repairs. Ensure charts apply to engine being tested.

Before proceeding with diagnosis, the following precautions must be followed:

• Vehicle must have a fully charged battery and functional charging system.
• Probe SBEC connector from pin side. DO NOT  backprobe SBEC connector.
• DO NOT  cause short circuits when performing electrical tests. This will set additional 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 coil wire is more than 1/4" from ground, damage to vehicle electronics and/or SBEC may result.
• DO NOT  prolong testing of fuel injectors or engine may hydrostatically (liquid) lock.
• Always repair lowest fault code number (check engine light) or first fault displayed (DRB-II) first.
• Always perform verification test after repairs are made.