Diagnostic System Check - SCR System Controls

Diagnostic System Check - SCR System Controls

Description

The Diagnostic System Check - SCR System Controls is an organized approach to identifying a condition that is created by a malfunction in the electronic control system. The Diagnostic System Check must be the starting point for any SCR system concern. The Diagnostic System Check directs the service technician to the next logical step in order to diagnose the concern. Understanding and correctly using the diagnostic table reduces diagnostic time, and prevents the replacement of good parts.

Test Description

The numbers below refer to the step numbers on the diagnostic table.
2. Lack of communication may be because of a partial or a total malfunction of the CAN circuit. The specified procedure determines the particular condition.
4. The presence of DTCs which begin with U, indicate that some other module is not communicating.
8. If there are other modules with DTCs set, refer to the DTC list. The DTC list directs you to the appropriate diagnostic procedure. If the control module stores multiple DTCs, diagnose the DTCs in the following order:
- Component level DTCs, such as sensor DTCs, solenoid DTCs, actuator DTCs, and relay DTCs. Diagnose the multiple DTCs within this category in numerical order. Begin with the lowest numbered DTC, unless the diagnostic table directs you otherwise.
- DO NOT perform this diagnostic if there is not a SCR System concern, unless another procedure directs you to this diagnostic.
- Before you proceed with diagnosis, search for applicable service bulletins.
- Unless a diagnostic procedure instructs you, DO NOT clear the DTCs.
- Ensure the battery has a full charge.
- Ensure the battery cables (+) (-) are clean and tight.
- Ensure the DEF control module grounds are clean, tight, and in the correct location.
- Ensure the DEF control module harness connectors are clean and correctly connected.
- Ensure the DEF control module terminals are clean and correctly mating.
- Ensure the correct software/ calibration is programmed into the DEF control module.
- Ensure certified DEF is being used.

Diagnostic System Check - SCR System Controls