0123234 JOHNSON HOUSING,Lower

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's 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's 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.ECM Activation of the Fuel Priming PumpThis strategy improves the capability of the fuel system at low engine speeds.The ECM will automatically activate the fuel priming pump while the engine state is CRANKING, RUNNING, or POSTRUN. The ECM deactivates the fuel pump when the engine speed is greater than 200 rpm. Manual Override of the Fuel Priming PumpA "Fuel Priming Pump Command Override" that is in Caterpillar Electronic Technician (ET) can be used to diagnose the circuit that is for the electric fuel priming pump. A "Fuel Priming Pump Command" parameter is also available in Cat ET that can be used to view the status of the ECM output.When the override is activated, the ECM powers the electric fuel priming pump. The ECM will command the throttle position to 25 percent. This provides a path for air to escape from the low pressure fuel system. To use this feature, the ECM and the keyswitch relay must be powered. Also, the engine speed must be 0 rpm.
Illustration 1 g01534755
Schematic for the electric fuel priming pump
Test Step 1. Inspect the Electrical Connectors and the Wiring
Turn the battery disconnect switch to the OFF position.
Illustration 2 g01535534
Location of the connectors at the control box that are for the electric fuel priming pump (typical top front engine view)
(1) Right rail connector
(2) J1/P1 ECM connector
(3) J2/P2 ECM connector
(4) Fuel pump relay
(5) Control Box
Illustration 3 g01535554
Location of the low current power distribution panel (front left side engine view)
(6) Harness for the low current power distribution panel
(7) Low current power distribution panel
Illustration 4 g01535555
Location of the connectors and the fuses at the low current power distribution panel
(8) Gray connector
(9) Fuse for the electric fuel priming pump
(10) −Battery
(11) +Battery
Illustration 5 g01535535
Location of the connectors for the fuel priming pump (typical front right engine view)
(12) Connector for the electric fuel priming pump
Thoroughly inspect connectors (1), (2), (3), (4), and (5). Refer to Troubleshooting, "Electrical Connectors - Inspect".
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Terminal locations for the high pressure fuel pump at the P1 ECM connectors
(P1-10) Fuel priming pump
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Terminal locations for the high pressure fuel pump at the P2 ECM connectors
(P2-14) Digital return
Illustration 8 g01535537
Terminal locations at the right rail connector for the electric fuel priming pump
(Terminal 18) Return
(Terminal 19) Relay signal circuit to the pump
Illustration 9 g01535553
Terminal locations at the control box connector for the low current power distribution panel that are for the electric fuel priming pump
(Terminal 59) Relay signal circuit to the pump
(Terminal 60) Return
Illustration 10 g01535556
Terminal locations at the low current power distribution panel for the fuel priming pump