The DTC Type Definitions contain the characteristics for all types of DTCs. Each DTC type may or may not be found in this section. The DTC type is based on the action that the ECM and TCM takes when storing DTC information, and whether or not the TCM requests the TCM to illuminate a service lamp or display a message on a driver information center (DIC). The DTC descriptions in the Diagnostic Trouble Code List/Type below are listed in numeric order and indicate the DTC types for domestic vehicle applications. Each DTC is categorized into one of the following types:

Type A

This DTC is emissions related. The ECM stores the DTC in Freeze Frame and Failure Records, while the TCM stores the DTC in History and Failrue Records during the first trip in which the conditions for setting the DTC are met. The TCM also requests the ECM to illuminate the malfunction indicator lamp (MIL) during the first trip in which the conditions for setting the DTC are met.

Type B

This DTC is emissions related. The TCM stores the DTC in Failure Records during the first trip in which the conditions for setting the DTC are met. During the second consecutive trip in which the conditions for setting the DTC are met, the TCM stores the DTC in History and the ECM stores the DTC in Freeze Frame. The TCM also requests the TCM to illuminate the MIL during the second consecutive trip in which the conditions for setting the DTC are met.

Type C

This DTC is non-emissions related. The TCM stores the DTC in History and Failure Records during the first trip in which the conditions for setting the DTC are met. The TCM does not store the DTC in Freeze Frame and does not request the TCM to illuminate the MIL. For some type C DTCs, a message may be displayed on a DIC, if equipped. For other type C DTCs, a separate service lamp, other than the MIL, may be illuminated. Type C DTCs that do not display a message on the DIC or illuminate a separate service lamp were formerly referred to as type D.