DDEC III/IV Single ECM Troubleshooting – Section 9.1 First Step for Diagnosing a Fault Within the DDEC System

Section 9.1
First Step for Diagnosing a Fault Within the DDEC System

The following procedure is the starting point for diagnosing DDEC codes using the Diagnostic Data Reader (DDR).‪

Section 9.1.1
Check Engine Light

Perform the following steps to check the Check Engine Light (CEL):‪

1. Turn the ignition on while at the same time observing the Check/Stop Engine light (engine not running).
   1. If the CEL comes on and stays on, refer to "9.1.2 Read Active Codes" .
   2. If the CEL comes on for up to five seconds, and then turns off, refer to "9.1.3 Read Inactive Codes" .
   3. If the CEL does come on, but the condition of light is erratic or intermittent, refer to "10.4 Check Engine Light and Stop Engine Light Fault" .
   4. If the CEL does not come on, refer to "10 Intermittent Fault" and choose the appropriate symptom.

Section 9.1.2
Read Active Codes

Perform the following steps to read the active codes.‪

1. Turn ignition on. Plug DDR into DDL connector. See Figure "Diagnostic Connector" .
   

   Figure 1. Diagnostic Connector

2. Read active codes by selecting the DIAGNOSTIC CODE MENU (ACTIVE CODES) on the DDR.
   1. If active codes are displayed on the DDR, follow the appropriate diagnostic procedures for the codes received. Refer to the section number that is the same as the Flash Code number.
   2. If the DDR display is blank or random, refer to "10.5 No Data to Diagnostic Data Reader" .
   3. If DDR displays NO DATA or DDEC Info not available, refer to "10.5 No Data to Diagnostic Data Reader" .
   4. If the DDR display reads "No Active Codes", refer to "10.4 Check Engine Light and Stop Engine Light Fault" .

Section 9.1.3
Read Inactive Codes

Perform the following steps to read inactive codes.‪

1. Plug DDR into the DDL connector.
2. Read inactive codes. (Select inactive codes on the DDR.)
   1. If DDR displays no inactive codes, the problem may be intermittent. Refer to "10.1 Intermittent Code or a Symptom and No Codes" .
   2. If DDR display is blank or random, refer to "10.5 No Data to Diagnostic Data Reader" .
   3. If DDR displays NO DATA or DDEC Info not available, refer to "10.5 No Data to Diagnostic Data Reader" .
   4. If the DDR displays any inactive codes, clear the codes and refer to "9.1.4 Attempt to Make Codes Active" .

Section 9.1.4
Attempt to Make Codes Active

Perform the following steps to read the active codes.‪

1. Start and run the engine for eight minutes. Warm the engine. Coolant/oil temperature must be greater than 140°F (60°C).
2. If required, perform road test with an assistant.
   1. If CEL or SEL illuminate, read codes and refer to the section number that matches the flash code number logged.
   2. If CEL or SEL do not illuminate and no codes log, return to service.
   3. If CEL or SEL do not illuminate but symptom occurs, refer to "10.1 Intermittent Code or a Symptom and No Codes" , and Diagnosis by Symptom.