How to Check for DTCs with the HDS When the ECM senses a malfunction in the system, the MIL (A) or the glow plug indicator (B) in the gauge assembly will come on. When the HDS is connected to the data link connector (DLC) (located under the driver's side of the dashboard), it will indicate the diagnostic trouble code (DTC) when the ignition switch is turned ON (II). If the MIL or the glow plug indicator has been reported on, or if a driveability problem is suspected, follow this procedure: |