16256 1 Mercury PIN

Table 1
J1939 Code and Description CDL Code and Description Comments
931-5
Engine Fuel Supply Pump Actuator : Current Below Normal 1627-5
Fuel Pump Relay : Current Below Normal The Electronic Control Module (ECM) detects an open circuit or a short to +Battery in the circuit for the fuel pump relay for 60 seconds.
The ECM can only detect this condition when the output driver is not activated.
The code is logged.
931-6
Engine Fuel Supply Pump Actuator : Current Above Normal 1627-6
Fuel Pump Relay : Current Above Normal The engine ECM detects a short to ground in the circuit for the fuel pump relay.
The ECM can only detect this condition when the output driver is activated.
The code is logged. The ECM is used to energize the fuel pump relay. The fuel pump relay controls battery power to the fuel priming pump. The circuit that is for battery power uses a 15 amp fuse for circuit protection.Automatically Priming the Fuel SystemWhen the keyswitch is turned to the ON position, the engine ECM uses an automatic fuel priming strategy to pressurize the low-pressure fuel system. The engine ECM also powers the fuel priming pump during engine cranking.An override parameter on Caterpillar Electronic Technician (ET) allows the technician to activate the fuel priming pump. The test is only functional when the engine speed is zero rpm. Access the test via the "Override Parameters" screen on Cat ET.
Illustration 1 g02301755
Typical schematic for the fuel priming pump
Table 2
Troubleshooting Test Steps Values Results
1. Inspect the Electrical Connectors and the Wiring
A. Turn the keyswitch to the OFF position.
B. Thoroughly inspect the connectors. Refer to Troubleshooting, "Electrical Connectors-Inspect" for additional information.
C. Perform a 45 N (10 lb) pull test on the connector wires.
D. Check the harness for abrasions and pinch points.
Connectors and Wiring
Result: The connectors and wiring appear to be OK.
Proceed to Test Step .
Result: There is a problem with the connectors and/or wiring.
Repair: Repair or replace the connectors or wiring. Ensure that all the seals are properly in place and ensure that the connectors are coupled.
If the problem is not resolved, proceed to Test Step 2.
2. Check for Codes
A. Connect Cat® Electronic Technician (ET) to the service tool connector.
B. Determine if a code is active or logged.
Codes
Result: No diagnostic codes are active, but a problem is suspected in the circuit for the fuel priming pump.
Proceed to Test Step 6.
Result: A -5 diagnostic code is active currently.
Proceed to Test Step 4.
Result: A -6 diagnostic code is active currently.
Proceed to Test Step 3.
3. Create an Open at the Connector for the Fuel Pump Relay
A. Remove power from the ECM.
B. Turn the keyswitch to the OFF position.
C. Disconnect the connector from the fuel pump relay.
D. Restore power to the ECM.
E. Turn the keyswitch to the ON position.
F. Select diagnostic tests from Cat ET.
G. Select the "Override Parameters" screen on Cat ET.
H. Activate the override for the fuel pump relay.
I. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.
J. Deactivate the override for the fuel pump relay.
K. Again, monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.
A -5 Code
Result: A -5 diagnostic code became active after disconnecting the connector for the fuel priming pump.
Repair: Temporarily install a new fuel pump relay. Verify that there are no active diagnostic codes for the fuel pump relay. Clear any logged diagnostic codes.
If the problem is not resolved, proceed to Test Step 4.
Result: A -6 diagnostic code remains active. There is a short between the connector for the fuel pump relay and the ECM.
Proceed to Test Step 5.
4. Create a Short at the Connector for the Fuel Pump Relay
A. Remove power from the ECM.
B. Turn the keyswitch to the OFF position.
C. Disconnect the connector for the fuel pump relay. Install a jumper wire between terminal 2 and terminal 3 at the connector for the fuel pump relay.
D. Restore power to the ECM.
E. Turn the keyswitch to the ON position.
F. Select diagnostic tests from Cat ET.
G. Select the "Override Parameters" screen on Cat ET.
H. Activate the override for the fuel pump relay.
I. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.
J. Deactivate the override for the fuel pump relay.
K. Again, monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.
A -6 Code
Result: A -6 is active with the jumper in place. The engine harness and the ECM are OK.
Repair: Temporarily install a new fuel pump relay. Verify that there are no active diagnostic codes for the fuel pump relay. Clear any logged diagnostic codes.
If the problem is not resolved, proceed to Test Step 5.
Result: The -5 diagnostic code remains active with the jumper in place. Verify that the wire at terminal 5 (return) between the fuel pump relay and the ECM has continuity. If the return circuit is OK, there may be an open circuit between the ECM and the connector for the relay.
Proceed to Test Step 5.
5. Check for Proper Operation of the ECM
A. Remove power from the ECM.
B. Turn the keyswitch to the OFF position.
C. Check the operation of the ECM by creating an open at the ECM connector.
D. Check the operation of the ECM by creating a short circuit at the ECM connector.
E. Remove power from the ECM. Restore all wiring to the original configuration.
-5 and -6 Codes
Result: The ECM is operating properly. The problem is in the wiring between the ECM and the connector for the fuel pump relay.
Repair: Repair the connectors or wiring and/or replace the connectors or wiring.
If the problem is not resolved, proceed to Test Step 6.
Result: One of the following conditions exists: The -5 diagnostic code is not active when the jumper wire is open. The -6 diagnostic code is not active when the jumper wire is grounded.
Repair: There may be a problem with the ECM. Before you consider replacing the ECM, consult with the Dealer Solutions Network (DSN).
If the problem is not resolved, proceed to Test Step 6.
6. Check the Battery Circuit to the Relay
A. Disconnect