18811T Mercruiser CONTROL UNIT

Table 1
Diagnostic Trouble Codes for the DEF Pump Pressure Sensor
J1939 Code CDL Code Code Description
(code descriptions may vary) Comments
4334-3 3090-3 Aftertreatment 1 Diesel Exhaust Fluid Doser 1 Absolute Pressure : Voltage Above Normal There is excessive voltage on the signal wire between the Electronic Control Module (ECM) and the DEF pump.
or
There is an open circuit on the supply, signal, or return wire.
The code is logged.
4334-4 3090-4 Aftertreatment 1 Diesel Exhaust Fluid Doser 1 Absolute Pressure : Voltage Below Normal There is low voltage on the signal wire between the ECM and the DEF pump pressure sensor.
The code is logged.
Follow the troubleshooting procedure to identify the root cause of the problem.
Illustration 1 g06208827
Illustration 2 g06208829
View of the pin locations for the DEF pump on the P1 ECM connector
(28) DEF pump pressure sensor signal
(46) DEF pump pressure sensor 5 VDC supply
(50) DEF pump pressure sensor return
Illustration 3 g03416460
Pin location on the DEF pump connector
(2) Pressure sensor supply
(3) Pressure sensor signal
(4) Pressure sensor return
Table 2
Required Tools
Tool Part Number Part Description Qty
A 372-5260 Test Kit 1 Complete the procedure in the order in which the steps are listed.
Table 3
Troubleshooting Test Steps Values Results
1. Determine the Diagnostic Code
A. Establish communication between the electronic service tool and the engine Electronic Control Module (ECM). Refer to Troubleshooting, "Electronic Service Tools"
B. Check for active or logged codes.
Diagnostic trouble codes
Result: There is an active or logged 4334-3 (3090-3) or 4334-4(3090-4) diagnostic code.
Proceed to Test Step 2.
2. Inspect Electrical Connectors and Wiring
A. Inspect the P1 ECM connector.
B. Inspect the connector for the DEF pump.
C. Perform a 45 N (10 lb) pull test on each of the wires in the P1 ECM connector and the connector for the DEF pump.
D. Check all the wiring associated with the DEF pump for abrasions and pinch points.
Damaged wire or connector
Result: A damaged wire or damaged connector was not found.
Proceed to Test Step 3.
Result: A damaged wire or damaged connector was found.
Repair: Repair the damaged wire or the damaged connector.
Use the electronic service tool to clear all logged diagnostic codes. Verify that the repair eliminates the fault.
3. Check for an Open Circuit in the Wiring Harness for the DEF Pump Pressure Sensor Circuit
A. Turn the keyswitch to the OFF position for 2 minutes. The keyswitch must be OFF for 2 minutes to allow the DEF pump to purge, reset the code, and reset the ECM.
B. Disconnect the wiring harness from the DEF pump and the P1 connector on the ECM.
C. Connect Tooling A to the DEF pump connector.
Note: The connector must be used to prevent damage to the DEF pump connector.
D. Measure the resistance between terminal 2 (SUPPLY) on the DEF pump connector and P1:46.
E. Measure the resistance between terminal 3 (SIGNAL) on the DEF pump connector and P1:28.
F. Measure the resistance between terminal 4 (RETURN) on the DEF pump connector and P1:50.
Less than 5.0 Ohms
Result: All resistance measurements are less than 5.0 Ohms.
Proceed to Test Step 4.
Result: At least one of the resistance measurements is greater than 5.0 Ohms. There is an open in the harness.
Repair: Repair the wiring or replace the harness.
Verify that the fault is resolved.
Proceed to Test Step 6.
4. Check for Short Circuits in the Wiring Harness for the DEF Pump Pressure Sensor Circuit
A. Turn the keyswitch to the "OFF" position.
B. Disconnect the wiring harness from the DEF pump and P1 on the ECM.
C. Connect Tooling A to the DEF pump connector.
Note: The connector must be used to prevent damage to the DEF pump connector.
D. Measure the resistance between terminal 2 (SUPPLY) on the DEF pump connector and a known good chassis ground.
E. Measure the resistance between terminal 3 (SIGNAL) on the DEF pump connector and a known good chassis ground.
F. Measure the resistance between terminal 4 (RETURN) on the DEF pump connector and a known good chassis ground.
Greater than 100k Ohms
Result: All resistance measurements are greater than 100k Ohms.
Proceed to Test Step 5.
Result: At least one of the resistance measurements is less than 100k Ohms. There is a short circuit in the harness.
Repair: Repair the wiring or replace the harness.
Verify that the fault is resolved.
Proceed to Test Step 6.
5. Check for Short Circuits Between the DEF Pump Pressure Sensor and the ECM
A. Turn the keyswitch to the "OFF" position.
B. Disconnect the wiring harness from the DEF pump and P1 on the ECM.
D. Measure the resistance between P1:46 and all other pins in the P1 connector.
E. Measure the resistance between P1:28 and all other pins in the P1 connector.
F. Measure the resistance between P1:50 and all other pins in the P1 connector.
Greater than 100k Ohms
Result: All the resistance measurements are greater than 100k Ohms. A failed DEF pump has been detected.
Repair: Replace the DEF pump.
Proceed to Test Step 6.
Result: At least one of the resistance measurements is less than 100k Ohms. There is a short circuit in the harness.
Repair: Repair the wiring or replace the harness.
Verify that the fault is resolved.
Proceed to Test Step 6.
6. Perform a DEF Dosing System Verification Test
A. Turn the keyswitch to the "ON" position. Do not start the engine.
B. Connect the electronic service tool to the diagnostic connector.
C. Perform the "DEF Dosing System Verification Test" .
Diagnostic codes
Result: The code did not return.
Return the unit to service.
Result: The code returned.
Contact the Dealer Solutions Network (DSN).