DDEC III/IV Single ECM Troubleshooting – Section 5.1 Reading the Diagnostic Codes – Flash Method

Section 5.1
Reading the Diagnostic Codes - Flash Method

The following steps describe the flash method to interpret diagnostic codes:‪

Note: If you are here to begin diagnosis of a problem and already know how to read codes, as well as understand active and inactive codes, refer to "9.1 First Step for Diagnosing a Fault Within the DDEC System" .

1. Active versus Inactive codes:
   1. Active codes are the codes which are currently keeping the "Check or Stop Engine" light on. Active codes are flashed via the Stop Engine Light (SEL).
   2. Inactive codes are all the codes previously logged in the ECM. These codes can be cleared by using the DDR. Inactive codes are flashed via the Check Engine Light (CEL).

   Note: The Diagnostic Request Switch reads codes on the CEL and SEL when an DDR is not available. The following steps will enable you to obtain codes.

2. Turn vehicle ignition switch ON.
3. Depress and hold the diagnostic request switch.
   1. As an example, observe Code 13 (active) and Code 21 (inactive) flashing out on the CEL and SEL; see Figure "Flash Code Method" .
   2. If input used is SEO/Diagnostic Request, press and release the switch.
   3. If input used is Diagnostic Request, press and hold switch.

   Note: Active codes are flashed in ascending numerical flash code order. Inactive codes are flashed in most recent to least recent order.

   

   Figure 1. Flash Code Method

Section 5.1.1
Clearing Codes

Fault codes can only be cleared using the DDR.‪

Note: Removing the battery cables will not clear codes.