812820 1 Mercury NUT

Table 1
Diagnostic Codes Table
Code and Description Conditions which Generate this Code System Response
1627-5 Fuel Pump Relay current below normal The engine Electronic Control Module (ECM) detects an open circuit at the fuel pump relay for 60 seconds.
The ECM detects a short to battery voltage 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.
1627-6 Fuel Pump Relay current above normal The engine ECM detects a short circuit for the fuel pump relay.
The ECM can only detect this condition when the output driver is activated. The ECM has the ability to energize the fuel pump relay. The fuel pump relay controls battery power to the fuel priming pump.A test on Caterpillar Electronic Technician (ET) allows the technician to energize the fuel pump relay. The test is functional when engine speed is 0 rpm. The ECM will energize the output for the fuel pump relay for 120 seconds. The test is accessed by selecting the following menus on Cat ET:
"Diagnostics"
"Diagnostic Tests"
"Override Parameters"
Illustration 1 g01302442
Typical schematic
Illustration 2 g01141049
Typical location of the P1 ECM connectors
Illustration 3 g01302446
P1 ECM connector
(P1-19) Fuel pump relay
Illustration 4 g01149844
Terminal locations of the fuel pump relay
Recommended Actions
Table 2
Troubleshooting Test Steps Values Results
1. Check for Active Diagnostic Codes
A. Connect Cat ET to the service tool connector.
B. Turn the keyswitch to the ON position.
C. Select diagnostic tests from Cat ET.
D. Select the "Override Parameters" screen on Cat ET.
E. Activate the override for the fuel pump relay.
F. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.
Note: Wait at least 30 seconds in order for the diagnostic code to become active.
G. Deactivate the override for the fuel pump relay.
H. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.
Note: Wait at least 70 seconds in order for the diagnostic codes to become active.
Codes
Result: No diagnostic codes are active, but a problem is suspected in the circuit for the fuel priming
Proceed to Test Step 5
Result: A -6 diagnostic code is active now.
Proceed to Test Step 2.
Result: A -5 diagnostic code is active now.
Proceed to Test Step 3.
2. 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 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.
Note:Wait at least 30 seconds in order for the diagnostic code to become active.
J. Deactivate the override for the fuel pump relay.
K. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.
Note:Wait at least 70 seconds in order for the diagnostic codes to become active.
-5 Code
Result:A -5 diagnostic code became active after disconnecting the connector.
Repair: Temporarily connect a new fuel pump relay to the harness, but do not install the new fuel pump relay. Verify that there are no active diagnostic codes for the fuel pump relay. If there are no active diagnostic codes for the fuel pump relay, permanently install the new fuel pump relay. Clear any logged diagnostic codes.
STOP
Result: A -6 diagnostic code remains active. There is a short between the connector for the fuelpump relay and the ECM.
Proceed to Test Step 4.
3. 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 5 and terminal 2 at the connector for the fuel pump relay. Refer to Illustration 1 for the schematic of the circuit.
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.
Note:Wait at least 30 seconds in order for the diagnostic code to become active.
J. Deactivate the override for the fuel pump relay.
K. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.
Note:Wait at least 70 seconds in order for the diagnostic codes to become active.
-6 Code
Result: The engine harness and the ECM are OK.
Repair: Temporarily connect a new fuel pump relay to the harness, but do not install the new fuel pump relay. Verify that there are no active diagnostic codes for the fuel pump relay. If there are no active diagnostic codes for the fuel pump relay, permanently install the new fuel pump relay. Clear any logged diagnostic codes.
STOP
Result: The -5 diagnostic code remains active with the jumper in place. Verify that wire 229-BK on terminal 2 of the connector for the fuel pump relay has continuity to engine ground. If wire 229-BK is OK, the open circuit is between the ECM and the connector for the fuel pump relay.
Proceed to Test Step 4.
4. Check the 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:
a. Disconnect the J1/P1 ECM connector.
b. Remove the wire for the fuel pump relay from P1-19.
c. Install a wire jumper into the socket for P1-19. Ensure that the wire jumper is not in contact with any other wire in the harness or in contact with engine ground.
d. Reconne