99391 Mercury RETAINER

Illustration 1 g06134990
Schematic for the DCU and DEF quality sensor electrical power supply circuit
Illustration 2 g03421149
Pin locations on the P1 connector for the power supply circuit
(2) DCU keyswitch
(3) DCU keyswitch
(5) DCU power relay signal
(15) DCU power relay return
Illustration 3 g03155919
Pin locations on the DCU C2 connector for the power supply circuit
(1) Battery -
(2) Battery -
(3) Battery -
(4) Battery -
(5) Battery -
(6) Battery +
(7) Battery +
(8) Battery +
(9) Battery +
(52) KeyswitchComplete the procedure in the order in which the steps are listed.
Table 2
Troubleshooting Test Steps Value Results
1. Inspect Electrical Connectors and Wiring
A. Ensure that the battery disconnect switch is in the OFF position.
B. Thoroughly inspect all connectors associated with the DEF control module power supply.
C. Check all fuses.
D. Perform a 45 N (10 lb) pull test on each of the wires in the connectors associated with the power supply.
E. Check all the wiring associated with the electrical power supplies for abrasions and pinch points.
Damaged wire or connector. Blown fuse.
Result: A damaged wire or damaged connector was not found. The fuses are OK.
Proceed to Test Step 2.
Result: A damaged wire or damaged connector was found. A blown fuse was found.
Repair: Repair the damaged wire or the damaged connector. Replace all blown fuses.
Use the electronic service tool to clear all logged diagnostic codes. Verify that the repair eliminates the fault.
2. Check for Active Diagnostic Codes
A. Establish communication between the electronic service tool and the ECM. Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Check the "Active Diagnostics" screen on the electronic service tool.
Diagnostic code
Result: A 3360-X or 3820-X diagnostic code is active.
Proceed to Table 3, "Troubleshooting Procedure for the DCU Power Supply".
Result: There is a problem with the power supply to the DEF quality sensor.
Proceed to Table 3, "Troubleshooting Procedure for the DCU Power Supply" - Test Step 7.
Result: A 5965-5 or 3838-5 diagnostic code is active.
Proceed to Table 4, "Troubleshooting for the Main DCU Power Relay" - Test Step 1.
Result: A 5965-6 or 3838-6 diagnostic code is active.
Proceed to Table 4, "Troubleshooting for the Main DCU Power Relay" - Test Step 4.
Result: A 5966-5, 3965-5, 6309-5 or 3966-5 diagnostic code is active.
Proceed to Table 5, "Troubleshooting Procedure for the DCU Keyswitch Signal" - Test Step 1.
Result: A 5966-6, 3965-6, 6309-6 or 3966-6 diagnostic code is active.
Proceed to Table 5, "Troubleshooting Procedure for the DCU Keyswitch Signal" - Test Step 4.
Table 3
Troubleshooting Procedure for the DCU Power Supply
Troubleshooting Test Steps Value Results
1. Check the Voltage at the PETU Power Connector
A. Disconnect the PETU power connector.
B. Use a suitable multimeter to take the following voltage measurements at the PETU power connector (application side).
Terminal 1 to terminal 3
Terminal 2 to terminal 4
Battery voltage
Result: The measured voltage is equal to battery voltage.
Reconnect the PETU power connector. Proceed to Test Step 2.
Result: The measured voltage is not equal to battery voltage.
Repair: Replace the wiring between the battery and the PETU power connector.
Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
2. Check the Voltage to the DCU Power Relay
A. Disconnect the main DCU power relay.
B. Measure the voltage between terminal 1 on the harness connector for the relay and a suitable ground.
Battery voltage
Result: The measured voltage is equal to battery voltage.
Reconnect the DCU power relay. Proceed to Test step 3.
Result: The measured voltage is not equal to battery voltage.
Repair: Replace the wiring between the PETU power connector and the DCU power relay.
Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
3. Check the Voltage to the VLPM
A. Disconnect the VLPM.
B. Turn the keyswitch to the ON position. Do not attempt to start the engine.
C. Measure the voltage between terminal 1 on the harness connector for the VLPM and suitable ground.
D. Turn the keyswitch to the OFF position.