DDEC III/IV Single ECM Troubleshooting – Section 51.3 Troubleshooting Flash Code 51

Section 51.3
Troubleshooting Flash Code 51

Perform the following steps to troubleshoot code 51: ‪

Section 51.3.1
Check for Codes

Follow these steps to check for codes:‪

1. Unplug coding sensor.
2. Insert jumper wire; #1–#2 (404 code) or #4–#1 (351 code). See Figure "Turbo Compressor Inlet Sensor" .
3. Start and run engine for six minutes.
   1. If code 404 or 351 FMI 3 display, refer to "51.3.2 Check for Open" .
   2. If code 404 or 351 FMI 4 display, go to section "51.3.3 Check Connectors" .

Section 51.3.2
Check for Open

The steps that brought you to this procedure indicate either the signal wire or return is open. Follow these steps to check for open: ‪

1. If code 351 displays, check cavity 7 at the 10–pin connector.
2. Determine if repair was made.
   1. If the repair was made, refer to "51.3.4 Verify Procedure" .
   2. If the repair was not made, replace the sensor. For code 351, replace TCI; code 404, replace TCO. Then refer to "51.3.4 Verify Procedure" .
3. Test the repair.

Figure 1. Turbo Compressor Inlet Sensor

Section 51.3.3
Check Connectors

Follow this procedure to check the 30–pin and 10–pin connectors.‪

1. If code 351 displays, check the connectors for damaged, bent or broken pins.See Figure "Turbocharger Compressor Outlet Temperature Circuit" .
   

   Figure 2. Turbocharger Compressor Outlet Temperature Circuit

   1. If damaged pins are found, repair the connector and test. Refer to "51.3.4 Verify Procedure" .
   2. If no damaged pins are found, replace the sensor. For code 404, replace TCO, code 351, replace TCI. Then, refer to "51.3.4 Verify Procedure" .

Section 51.3.4
Verify Procedure

Follow these steps to verify the procedure.‪

1. Reconnect all connectors.
2. Start and run the engine.
3. Check for codes.
   1. If codes 351 or 404 display, try a test ECM programmed for EGR.
   2. If no codes display, the procedure is finished.
   3. If codes other than 351 or 404 display, troubleshoot those codes.