Service Precautions

During diagnosis, following these precautions:

• Always relieve fuel pressure before disconnecting any fuel injection-related component. DO NOT  allow fuel to contact engine or electrical components. See FUEL PRESSURE RELEASE .
• When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in the GENERAL INFORMATION Section before disconnecting battery.
• Vehicle must have a fully charged battery and functional charging system.
• Probe PCM 60-pin connector from pin side. DO NOT  backprobe PCM connector.
• DO NOT  cause short circuits when performing electrical tests. This will set additional faults, making diagnosis of original problem more difficult.
• DO NOT  use a test light instead 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 PCM 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 procedure test after repairs are made.
• Always disconnect DRB-II after use.
• Always disconnect DRB-II before charging battery.