STRIP 9M6744 - Caterpillar

Use this procedure to troubleshoot a problem with the fuel priming pump. Also, use this procedure if one of the following diagnostic codes is active or easily repeated.
Table 1
J1939 Codes and Description CDL Codes and Description Comments
931-5
Engine Fuel Supply Pump Actuator : Current Below Normal 1627-5
Fuel Pump Relay : Current Below Normal This code indicates that there is a problem with the engine fuel priming pump relay and /or electrical circuit.
931-6
Engine Fuel Supply Pump Actuator : Current Above Normal 1627-6
Fuel Pump Relay : Current Above Normal This code indicates that there is a problem with the engine fuel priming pump relay and /or electrical circuit.
7102-5
Engine Fuel Filter Circulating Pump : Current Below Normal 4550-5
Electric Fuel Transfer Pump Relay : Current Below Normal The code indicates that there is a problem with the Clean Fuel Module (CFM) fuel priming pump relay and/or electrical circuit.
7102–6
Engine Fuel Filter Circulating Pump : Current Above Normal 4550-6
Electric Fuel Transfer Pump Relay : Current Above Normal The code indicates that there is a problem with the CFM fuel priming pump relay and/or electrical circuit. The engine is equipped with a Clean Fuel Module (CFM) which provides extra fuel filtration along with an extra fuel lift pump to pull fuel from the fuel tank. If equipped with the CFM module, the fuel will flow from the fuel tank, to the CFM priming pump, then through the CFM filters. Once the fuel leaves the CFM primary filters, the fuel flows into the engine fuel priming pump then flows into the fuel transfer pump. The fuel is pressurized and flows through the last fuel filter block secondary filter block before entering the high-pressure pump. The fuel is sent from the high-pressure pump, to the fuel rail, then flows through the injectors into the cylinders. Refer to Systems Operation, "Fuel System Operation" for more detail.
Illustration 1 g03812829
Schematic of the low-pressure fuel system with Clean Fuel Module (CFM).
(1) CFM
(2) Fuel Transfer Pump
(3) High-Pressure Fuel Pump
(4) Tank
Table 2
Component Electrical Checkout
Engine Fuel Supply Pump Actuator Fuel Pump Relay Command Override
Engine Fuel Filter Circulating Pump (CFM) Electric Fuel Transfer Pump Relay Override
Illustration 2 g06081953Probable Causes
Codes
Open circuit
Short circuitRecommended Actions
Table 3
Troubleshooting Test Steps Values Results
1. 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: A 931-5or 1627-5code is active or logged.
Proceed to Test Step 2.
Result: A 931-6or 1627-6 code is active or logged.
Proceed to Test Step 3.
Result: A 7102-5 or 4550-5 code is active or logged.
Proceed to Test Step 4.
Result: A 7102-6 or 4550-6 code is active or logged.
Proceed to Test Step 5.
2. Check the Wiring for an Open Circuit
A. Verify that the wiring harness connector is free of debris, free of corrosion, and securely connected.
B. Disconnect the solenoid from the engine harness.
C. Connect a jumper wire between the terminals of the harness connector for the suspect coil. The coil is replaced with a short circuit.
D. Perform the appropriate electrical checkout.
Open Circuit
Results: A -5 code became active during the electrical checkout.
The Electronic Control Module