Basic Diagnostic Procedure

Diagnosis of the DEC system should be performed in the following order:

1. Make sure that all engine systems related to the DEC system are operating properly. Do not proceed with testing unless all other problems have been repaired.
2. Proceed to the DIAGNOSTIC CIRCUIT CHECK FLOW CHART in the DIAGNOSTIC CIRCUIT CHECK test. Follow all instructions given in that chart.
3. If no trouble was indicated, proceed to DIESEL DIAGNOSTIC CHECK - TESTER CHECK chart.
4. After any repairs are made, perform the DIAGNOSTIC CIRCUIT CHECK test and follow the DIAGNOSTIC CIRCUIT CHECK FLOW CHART again.