Initial Inspection and Diagnostic Overview

Note: Perform before beginning System Diagnosis

1. Check that G400 is clean and tight.
2. Check PWR ACCY Fuse and Courtesy Fuse for open. If either fuse is open, check for short to ground through CKTs 640 and/or 40.
3. For vehicles with Manual Transmissions, the "BRAKE" Indicator receives a ground through the Park Brake Switch. Applying the Park Brake and observing the "BRAKE" Indicator can be used as a quick check of the ground CKT below S228.

^ Check for a broken (or partially broken) wire inside of the insulation which could cause system failure but prove "GOOD" in a continuity/voltage check. Use Test Light J 34142 whenever possible. Test lights require more current than a high impedance DVM and are more useful for detecting abnormally high resistive circuits. Some test lights have high impedances and will not be as useful in detecting resistive circuits.
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of other systems.