"Scan" Diagnostic Circuit Check - Testing: Notes
The "SCAN" diagnostic circuit check is an organized approach for identifying fuel injection problems using an assembly line communication link (ALCL). This communication link can provide diagnostic information for display on any scan device or tool designed for this purpose. The tool plugs into ALCL connector located below instrument panel. If a stored code is displayed, code definitions will aid in determining if fault is still present (hard failure) or result of an intermittent condition not normally diagnosed using code charts.
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- If scan tool is not operating, check on another vehicle. If okay, the cigar lighter socket should be checked for 12 volts and a good ground. If scan tool reads "no data" or "no ALCL" with ignition on, check serial data wire for an open or short to ground between ALCL terminal "E" and ECM. Also check for an open diagnostic test terminal for ALCL terminal "B" and ECM. With ignition on, serial data line (ALCL terminal "E") should have a varying 2-5 volts, and diagnostic line (ALCL terminal "B") about 5 volts.