Without Scan Tool

ECM CODES

A scan tool must be used to retrieve DTCs from the ECM memory. DTCs can no longer be retrieved by grounding terminals "A" to "B" at the Data Link Connector (DLC). This also eliminates the ECM function of flashing Code 12. The use of a Tech 1 scan tool or equivalent will be needed to obtain both current and history DTCs.

Data Link Connector:

Duty Check Data Link Connector Pinout-typical:

TCM CODES (Flash Code Method)

Diagnostic Trouble Codes (DTCs) stored in the Transmission Control Module (TCM) memory can also be read by counting the flashes of the "OD/OFF" indicator lamp after grounding the diagnostic request terminal in the duty check DLC No. 2. When the terminal is grounded, the TCM enters into diagnostic mode and outputs DTCs to the "OD/OFF" indicator lamp.

The duty check DLC No. 2 is the right front side of the engine compartment, next to the wiper washer reservoir. It is a black, 6 cavity connector.

Reading Diagnostic Trouble Codes (DTCs) is accomplished by connecting a jumper wire from terminal "1" to terminal "4" (ground). The TCM will then cause the "OD/OFF" indicator lamp to flash a coded number sequence. The number of flashes will equal the first digit of the two digit DTC. A 1.5-second pause will follow, and the second set of flashes will equal the second digit of the two digit DTC. If several DTCs have been stored, a 2.5-second pause will separate each DTC beginning with the smallest number DTC first.

If no malfunctions in the electronic control system exist, the "OD/OFF" indicator will flash once. A 1.5-second pause will follow. Then, two more one-second flashes indicating a DTC 12. DTC 12 indicates that no malfunctions in the electronic control system exist at this time. DTCs other than 12 indicate a malfunction in the electronic control system.

Refer to the "Flash Code to Diagnostic Trouble Code (DTC) Conversion Table" to find corresponding DTC chart. - Flash Code to DTC Code Conversion Table