C9.3 Tier 4 Final Engines Caterpillar

The high-pressure fuel pump contains two "pressurizing assemblies". Each assembly contains a solenoid. The Engine Electronic Control Module (ECM) sends 105 v pulses to each solenoid. The pulses are sent at the proper time and for the correct duration for a given engine load and speed.

The ECM monitors the current flow through the circuit for each solenoid. If the current flow is too high or too low, the ECM activates one of the following diagnostic codes:

Table 1

Diagnostic Trouble Codes
J1939 Code	CDL Code	Code Description	Comments
1347-5	1779-5	Fuel Rail #1 Pressure Valve Solenoid : Current Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
1347-6	1779-6	Fuel Rail #1 Pressure Valve Solenoid : Current Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
1348-5	1780-5	Fuel Rail #2 Pressure Valve Solenoid : Current Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
1348-6	1780-6	Fuel Rail #2 Pressure Valve Solenoid : Current Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.

Note: The automatic cylinder cutout test is disabled while any of these codes are active.

Automatic Configuration of the Solenoid Drivers

The connectors for the solenoids are interchangeable. The ECM determines the connector that is connected to each solenoid during each engine start cycle. For this reason, either pump solenoid can be driven by either ECM driver.

Illustration 1	g03343251

Illustration 2	g01959043
Typical left side view

Illustration 3	g01959046
Harness connectors for the solenoids

Complete the procedure in the order in which the steps are listed.

Table 2

Troubleshooting Test Steps	Values	Results
1. Determine the Diagnostic Code A. Establish communication between Cat® Electronic Technician (ET) and the applicable Electronic Control Module (ECM) . Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Download the "Warranty Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes. C. Look for an active or logged -5 code or -6 code.	Diagnostic Trouble Codes	Result: There is an active or there is a logged -5 code Proceed to Test Step 2. Result: There is an active or there is a logged -6 code. Proceed to Test Step 3.

Illustration 4	g03343300

Table 3

Troubleshooting Test Steps	Values	Results
2. Check the Wiring for an Open Circuit A. Turn the keyswitch to the OFF position. B. Verify that the harness connector is free of debris, free of corrosion and securely connected. C. Disconnect both solenoids from the harness. D. Connect a jumper wire between terminals 1 and 2 of the harness connector for each coil. Each coil is replaced with a short circuit. E. Turn the keyswitch to the ON position. Do not start the engine. F. Connect to Cat ET. Select the Diagnostics tab and perform the "Fuel Rail Pump Solenoid Test".	Short Circuit	Result: The test results indicate "Not OK (*Open)" for one or both solenoids. There is an open circuit in the wiring between a solenoid and the Engine Electronic Control Module (ECM) connector. Check both solenoid wiring circuits. There may be a problem with a connector. Repair: Repair the connectors and/or the wiring. Replace parts, if necessary. Verify that the original problem is resolved. Perform the "Fuel Rail Pump Solenoid Test" again to verify that the problem is resolved. Result: The test results indicate "Not OK (*Short)" for both solenoids. The Engine Electronic Control Module (ECM) detected the jumper wires. There is a problem with a solenoid. Repair: Replace the pump. Perform the "Fuel Rail Pump Solenoid Test" again to verify that the problem is resolved.

Illustration 5	g03343302

Table 4

Troubleshooting Test Steps	Values	Results
3. Check the Wiring for a Short Circuit A. Verify that the harness connector is free of debris, free of corrosion and securely connected. B. Connect to Cat ET, Select the Diagnostics tab, and perform the "Fuel Rail Pump Solenoid Test" C. Record the driver which has the "Not OK (*Short)" result. D. Remove the driver return wire from the ECM connector that has the "Not OK (*Short)" result. E. Disconnect the solenoid from the driver circuit that has the "Not OK (*Short)" result. F. Install a jumper wire between pins 1 and 2 on the solenoid connector. G. Connect to Cat ET. Select the Diagnostics tab and perform the "Fuel Rail Pump Solenoid Test".	Short Circuit	Result: The test results indicate "Not OK (*Short)". There is a short circuit in the wiring. There may be a problem with a connector. Repair: Repair the wiring. Replace parts, if necessary. Reconnect both solenoids and all wiring. Perform the "Fuel Rail Pump Solenoid Test" again. The test results will indicate "OK " if the short circuit is corrected. Result: The test results indicate "Not OK (*Open)" for the suspect driver wiring circuit. The ECM detected the open circuit. There is a problem with the solenoid. Repair: Replace the pump. Perform the "Fuel Rail Pump Solenoid Test" again to verify that the problem is resolved.