74726 Mercury WASHER, THROTTLE LEVER SCREW

Table 1
Diagnostic Trouble Codes
J1939 Code and Description CDL Code and Description Comments
411-15
High EGR Differential Pressure E1094 (1)
High EGR Differential Pressure The ECM detects an abnormally high reading from the NRS differential pressure sensor.
411-17
Low EGR Differential Pressure E1093 (1)
Low EGR Differential Pressure The ECM detects an abnormally low reading from the NRS differential pressure sensor.
2659-15
High EGR Mass Flow Rate E1096 (1)
High EGR Mass Flow Rate The ECM detects a higher than desired flow rate through the NRS
2659-17
Low EGR Mass Flow Rate E1095 (1)
Low EGR Mass Flow Rate The Electronic Control Module (ECM) detects a lower than desired flow rate through the NRS Note: EGR is an industry standard term used to describe the recirculation of exhaust gas through the engine as a means to reduce "NOx" emissions. Caterpillar has elected to refer to this system as the "NOx Reduction System" (NRS). Diagnostic codes are regulated by SAE, therefore, the diagnostic codes still reflect the EGR nomenclature.
Table 2
Associated Diagnostic Trouble Codes
E1154
E1092
3609-17
3609-18
412-15
412-16 Complete the procedure in the order in which the steps are listed.
Table 3
Troubleshooting Test Steps Values Results
1. Check for Diagnostic Trouble Codes
A. Establish communication between Cat® Electronic Technician (ET) and the ECM . Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Troubleshoot any active or logged diagnostic trouble codes before troubleshooting the event codes outlined in this procedure.
Determine if an associated code is active or logged. Table 2 lists associated diagnostic codes.
Associated Codes
Result: There are associated codes.
Repair: Refer to Troubleshooting, "Event Codes" to troubleshoot the associated diagnostic code.
Result: There are no associated codes. If the original diagnostic trouble code was a E1095, E1096, 2659-15 and/or a 2659-17.
Proceed to Test Step 2.
Result: There are no associated codes. If the original diagnostic trouble code was a E1093, E1094, 411-17 and/or 411-15.
Proceed to Test Step 5.
Result: There are no associated codes. If the original diagnostic trouble code was a E1095 or 2659-17.
Proceed to Test Step 3.
Illustration 1 g03768518
Inspection points for the left side of the engine
(1) NRS inlet valve
(2) NRS temperature sensor
(3) NRS outlet valve
Illustration 2 g03771076
Inspection points for the right side of the engine
(4) NRS cooler outlet
(5) NRS cooler inlet
(6) NRS bellows joint
Table 4
Troubleshooting Test Steps Values Results
2. Inspect the NRS for Leakage
A. Inspect the following components of the NRS for leakage:
1. Exhaust manifold
2. Connections for NRS cooler inlet and NRS cooler outlet
3. NRS venturi inlet and outlet connections
4. Port locations for NRS differential pressure sensor and NRS absolute pressure sensor
5. Connections for NRS inlet valve and NRS outlet valve
Common signs of a leak in the NRS are loose connections, damaged lines, or components and exhaust soot buildup around the area that is leaking.
Leakage
Result: Leaks were found in the system.
Repair: Repair the leaks.
Reset all active codes and clear all logged codes. Use Cat ET to perform an "EGR System Test" to verify that the problem is resolved.
Result: Leaks were not found in the system.
Proceed to Test Step 3.
3. Use Cat ET to Perform an "EGR System Test"
A. Start the engine.
B. Use Cat ET to perform an "EGR System Test".
Test Failed
Result: The "EGR System Test" fails due to "Delivered Fuel Volume Not Responding".
When the NRS gas flow is being commanded to change, no change in fuel delivery was measured. Increasing or decreasing the NRS gas flow will impact the amount of fuel needed to maintain the desired engine speed.
Proceed to Test Step 4.
Result: The "EGR System Test" fails due to "EGR Delta Pressure Not Responding".
The fault indicates that when the NRS valve moves from OPEN to CLOSED, no change in NRS delta pressure is measured.
Proceed to Test Step 5.
Result: The "EGR System Test" fails due to "EGR Absolute Pressure Not Responding".
The fault indicates that when the NRS valve moves from OPEN to CLOSED, no change in the NRS absolute pressure is measured.
Proceed to Test Step 6.
Result: The "EGR System Test" fails due to "EGR Mass Flow Rate Incorrect".
The fault indicates when the NRS valve moves from OPEN to CLOSED, the desired NRS mass flow is different from the actual mass flow rate.
Proceed to Test Step 4.
Illustration 3 g03771099
NRS valve
(7) NRS actuator assembly
(8) NRS valve body