C175-20 Locomotive Engine Caterpillar

Use this procedure to troubleshoot a problem with a solenoid valve. Also, use this procedure if one of the following diagnostic codes is active or easily repeated.

Table 1

J1939 Code and Description	CDL Code and Description	Comments
854-5 Heater Circuit #01 : Current Below Normal	4279-5 Ground Fault Switch #1 : Current Below Normal	This code indicates that there is a problem with the Diesel Exhaust Fluid (DEF) tank heater circuit breaker position circuit.
854-6 Heater Circuit #01 : Current Above Normal	4279-6 Ground Fault Switch #1 : Current Above Normal	This code indicates that there is a problem with the DEF tank heater circuit breaker position circuit.
4336-5 Aftertreatment #1 SCR Dosing Air Assist Valve : Current Below Normal	3094-5 Aftertreatment #1 SCR Dosing Air Assist Signal : Current Below Normal	This code indicates that there is a problem with the Dosing Air Assist Valve and/or the electrical circuit for the Dosing Air Assist Valve.
4336-6 Aftertreatment #1 SCR Dosing Air Assist Valve : Current Above Normal	3094-6 Aftertreatment #1 SCR Dosing Air Assist Signal : Current Above Normal	This code indicates that there is a problem with the Dosing Air Assist Valve and/or the electrical circuit for the Dosing Air Assist Valve.
4356-5 Aftertreatment #1 DEF Line Heater #3 : Current Below Normal	3112-5 Aftertreatment #1 DEF Line Heater #3 : Current Below Normal	This code indicates that there is a problem with the DEF line heater electrical circuit.
4356-6 Aftertreatment #1 DEF Line Heater #3 : Current Above Normal	3112-6 Aftertreatment #1 DEF Line Heater #3 : Current Above Normal	This code indicates that there is a problem with the DEF line heater electrical circuit.
4357-5 Aftertreatment #1 DEF Line Heater #4 : Current Below Normal	3113-5 Aftertreatment #1 DEF Line Heater #4 : Current Below Normal	This code indicates that there is a problem with the DEF line heater electrical circuit.
4357-6 Aftertreatment #1 DEF Line Heater #4 : Current Above Normal	3113-6 Aftertreatment #1 DEF Line Heater #4 : Current Above Normal	This code indicates that there is a problem with the DEF line heater electrical circuit.
4372-5 Aftertreatment #1 DEF Quick Thaw Heater : Current Below Normal	3606-5 Aftertreatment #1 DEF Tank Heater Relay : Current Below Normal	This code indicates that there is a problem with the DEF Quick Thaw Heater Relay and/or the electrical circuit for the DEF Quick Thaw Heater Relay.
4372-6 Aftertreatment #1 DEF Quick Thaw Heater : Current Above Normal	3606-6 Aftertreatment #1 DEF Tank Heater Relay : Current Above Normal	This code indicates that there is a problem with the DEF Quick Thaw Heater Relay and/or the electrical circuit for the DEF Quick Thaw Heater Relay.
4376-5 Aftertreatment #1 DEF Return Valve : Current Below Normal	3862-5 Aftertreatment #1 Diesel Exhaust Fluid Return Valve Solenoid : Current Below Normal	This code indicates that there is a problem with the Diesel Exhaust Fluid (DEF) Return Valve and/or the electrical circuit for the DEF Return Valve.
4376-6 Aftertreatment #1 DEF Return Valve : Current Above Normal	3862-6 Aftertreatment #1 Diesel Exhaust Fluid Return Valve Solenoid : Current Above Normal	This code indicates that there is a problem with the DEF Return Valve and/or the electrical circuit for the DEF Return Valve.
5434-5 Tank Fill Valve : Current Below Normal	N/A	This code indicates that there is a problem with the DEF Tank Fill Valve and/or the electrical circuit for the DEF Tank Fill Valve.
5434-6 Tank Fill Valve : Current Above Normal	N/A	This code indicates that there is a problem with the DEF Tank Fill Valve and/or the electrical circuit for the DEF Tank Fill Valve.
5706-5 Aftertreatment #1 DEF Pump Heater : Current Below Normal	4578-5 Aftertreatment #1 DEF Pump Heater : Current Below Normal	This code indicates that there is a problem with the DEF pump heater circuit.
5706-6 Aftertreatment #1 DEF Pump Heater : Current Above Normal	4578-6 Aftertreatment #1 DEF Pump Heater : Current Above Normal	This code indicates that there is a problem with the DEF pump heater circuit.
7416-5 Aftertreatment #1 DEF Pump Power Relay : Current Below Normal	N/A	This code indicates that there is a problem with the DEF pump power relay and/or the electrical circuit for the DEF pump power relay.
7416-6 Aftertreatment #1 DEF Pump Power Relay : Current Above Normal	N/A	This code indicates that there is a problem with the DEF pump power relay and/or the electrical circuit for the DEF pump power relay.
7417-5 Aftertreatment #1 DEF Control Module Circuit Breaker : Current Below Normal	N/A	This code indicates that there is a problem with the DEF control module circuit breaker or electrical circuit.
7417-6 Aftertreatment #1 DEF Control Module Circuit Breaker : Current Above Normal	N/A	This code indicates that there is a problem with the DEF control module circuit breaker or electrical circuit.

Electrical Checkouts on the Cat^® Electronic Technician (ET)

Table 2

Component	Electrical Checkout
Dosing Air Assist Valve	DEF Dosing Air Assist Valve Command Override
DEF Return Valve	DEF Return Valve Override
DEF Tank Fill Valve	DEF Tank Fill Valve Override
DEF Pump Power Relay	DEF Pump Power Relay Override
DEF Tank Heater Relay	DEF Tank Heater Relay Override

Illustration 1	g06373488

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 -5 code is active or logged. Proceed to Test Step 2. Result: A -6 code is active or logged. Proceed to Test Step 3. The Cat® Electronic Technician (ET) status screen will indicate "Conditions Not Met" when a diagnostic code is active for a particular component.
2. Check the Wiring for an Open Circuit A. Verify that the harness connector is free of debris, free of corrosion, and securely connected. B. Disconnect the solenoid from the harness. C. Install a jumper wire between the terminals of the harness connector for the affected coil. The coil is replaced with a short circuit.	Create a Short	Result: A -5 code became active during the electrical checkout. The Electronic Control Module (ECM) did not detect the jumper wire. There is an open circuit in the wiring between the coil and the ECM connector. There may be a problem with a connector. Repair: Repair or replace the connectors or the wiring. Verify that the repair eliminated the problem. Result: A -6 code is activated during the electrical checkout. The ECM detected the jumper wire. There is a problem with the solenoid. Repair: Replace the solenoid. Verify that the repair eliminated the problem.
3. Check the Wiring for a Short Circuit A. Disconnect the solenoid from the harness.	Create an Open	Result: A -6 code became active during the electrical checkout. The ECM did not detect the open circuit. There is a short circuit in the wiring between the coil and the ECM connector. There may be a problem with a connector. Repair: Repair or replace the connectors or the wiring. Verify that the repair eliminated the problem. Result: A -5 code is activated during the electrical checkout. The ECM detected the open circuit. There is a problem with the solenoid. Repair: Replace the solenoid. Verify that the repair eliminated the problem.

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).