5004742 JOHNSON NUT & CLIP LANYARD Assy

Table 1
Diagnostic Codes for the Fuel Priming Pump
CDL Code and Description Conditions which Generate the Code Comments
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.
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
Illustration 2 g01210818
Terminal locations at the fuel priming pump relay
(Terminal 1) Keyswitch Power
(Terminal 2) Return
(Terminal 3) Control circuit from the ECM
(Terminal 5) Power to the fuel priming pump
Illustration 3 g01155187
Terminal locations at the connector for the fuel priming pump
(Terminal 1) Power to the fuel priming pump
(Terminal 2) Return
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