Recommended Procedure

Connect scan tool to Data Link Connector (DLC). Using scan tool, access VPWR PID from PID/DATA MONITOR & RECORD menu. See ADDITIONAL SYSTEM FUNCTIONS in SELF-DIAGNOSTICS - 7.3L DIESEL article. Crank engine while monitoring VPWR PID reading. If VPWR PID reading indicates less than 8 volts, check charging circuit, power and ground circuits. See TEST A: VEHICLE BATTERY under SYSTEM TESTS in SELF-DIAGNOSTICS - 7.3L DIESEL article.