C15 and C18 – Exhaust System Contains Fuel | Caterpillar Engines Troubleshooting

Probable Causes

Short circuit in the ARD fuel pump relay wiring
Corrosion in the wiring harness connectors for the ARD fuel pump relay
Failed ARD fuel pump relay

Recommended Actions

Illustration 1 g03689122
Tier 4 Interim Schematic

Illustration 2 g03689125
Tier 4 Final Schematic

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

Carefully following this procedure is a good way to identify wiring problems.

Table 1
Troubleshooting Test Steps	Values	Results
1. Inspect the Components A. Visually inspect the components for the ARD fuel pump system. Look for the following problems: 1. Loose connections or damaged connectors 2. Moisture on the connectors or the wiring 3. Damage that is caused by excessive heat 4. Damage that is caused by chafing 5. Improper routing of wiring 6. Damaged insulation	Damaged Wiring or Connectors	Result: There is a problem with the wiring or a connector. Repair: Repair the wiring or connector. Replace parts, if necessary. Proceed to Test Step 4. Result: The wiring is OK. Proceed to Test Step 2.
2. Check for Voltage at the Coil for the ARD Fuel Pump Relay A. Turn the keyswitch to the OFF position. B. Measure voltage between the relay coil and a good ground source. There should not be voltage on the relay coil when the keyswitch is in the OFF position. Low amounts of voltage can keep the relay pulled in after the keyswitch has been turned to the OFF position.	Voltage	Result: There is voltage between the relay coil and a good ground source. There is a short from a power source in the wiring harness or there is moisture or corrosion in a connector between the ECM and ARD fuel pump relay coil. Make the necessary repairs. Proceed to Test Step 4. Result: There is not voltage between the relay coil and a good ground source. Proceed to Test Step 3.
3. Check for Voltage at the Load Side of the ARD Fuel Pump Relay A. Turn the keyswitch to the OFF position. B. Measure voltage between the load side of the ARD fuel pump relay and a good ground source.	Voltage	Result: There is voltage between the load side of the ARD fuel pump relay and a good ground source. Remove the relay. Check for voltage between the load side of the ARD fuel pump relay and a good ground source. If voltage is present, there is a short in the wiring between the relay and the ARD fuel pump. Repair or replace the wiring. If voltage is not present, the relay has failed. Repair: Replace the relay. Proceed to Test Step 4. Result: There is not voltage between the load side of the ARD fuel pump relay and a good ground source. Contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).
4. Clean Fuel from the Exhaust System A. Remove excess fuel from the piping with a clean cloth. B. Inhibit regeneration with the inhibit switch. C. Operate the engine at elevated idle (1500 RPM) for 20 minutes.	Excess Fuel	Result: The excess fuel and white smoke did not return after operating the engine for 20 minutes. Repair: Perform a Manual DPF Regeneration using Cat ET. Return the unit to service. Result: The excess fuel and white smoke returned after operating the engine for 20 minutes. Contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).

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