3516C Locomotive Engines Selective Catalytic Reduction Caterpillar

Relay - Test

Usage:

- LAS

System Operation Description:

Use this procedure to troubleshoot the electrical system if any of the diagnostic codes in Table 1 are active or easily repeated.

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Table 1
Diagnostic Codes
CDL Code and Description	Conditions which Generate this Code	System Response
3110-5 Aftertreatment #1 SCR Catalyst Reagent Line Heater #1:Current Below Normal Note: The code is for the supply side relay.	The Electronic Control Module (ECM) detects an open in the circuit for the relay.	The code is logged.
3110-6 Aftertreatment #1 SCR Catalyst Reagent Line Heater #1:Current Above Normal Note: The code is for the supply side relay.	The ECM detects a short in the circuit for the relay.	The code is logged.
3111-5 Aftertreatment #1 SCR Catalyst Reagent Line Heater #2:Current Below Normal Note: The code is for the return side relay.	The Electronic Control Module (ECM) detects an open in the circuit for the relay.	The code is logged.
3111-6 Aftertreatment #1 SCR Catalyst Reagent Line Heater #2:Current Above Normal Note: The code is for the return side relay.	The ECM detects a short in the circuit for the relay.	The code is logged.

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Illustration 1	g03413650
DEF heated line circuit (1) Connector for engine (A-C2) (2) Connector for CEM (A-C3) (3) Connector for tank (A-C13) (4) Engine mounted connector (ED-C1)

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In order to aid troubleshooting, overrides are provided via Cat ET.

Overrides allow the technician to turn the circuit on and off at will.

Refer to table 2 for the appropriate override for the code.

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Table 2
Component	Override
3110-5 Aftertreatment #1 SCR Catalyst Reagent Line Heater #1:Current Below Normal Note: The code is for the supply side relay.	Aftertreatment #1 SCR Catalyst Reagent Line Heater #1 State Override Note: The override is for the supply side relay.
3110-6 Aftertreatment #1 SCR Catalyst Reagent Line Heater #1:Current Above Normal Note: The code is for the supply side relay.
3111-5 Aftertreatment #1 SCR Catalyst Reagent Line Heater #2:Current Below Normal Note: The code is for the return side relay.	Aftertreatment #1 SCR Catalyst Reagent Line Heater #2 State Override Note: The override is for the return side relay.
3111-6 Aftertreatment #1 SCR Catalyst Reagent Line Heater #2:Current Above Normal Note: The code is for the return side relay.

Test Step 1. Determine the Diagnostic Code

Establish communication between Cat ET and the ECM . Refer to Troubleshooting, "Electronic Service Tools", if necessary.
Download the "Warranty Report" from the ECM before performing any troubleshooting or clearing diagnostic trouble codes.
Wait at least 30 seconds in order for the diagnostic codes to become active.
Look for these active codes or logged codes:
- -5
- -6

Results:

Test Step 2. Check the Wiring for an Open Circuit

Verify that the harness connectors are free of debris, free of corrosion and securely connected.
Disconnect the harness from the relay.
Connect a jumper wire between the terminals of the harness connector for the suspect relay. The relay is replaced with a short circuit.
Clear the -5 code.
Activate the override for the suspect circuit. Refer to table 2 for the appropriate override for the code.

Results:

A -5 code became active during the override. - The ECM did not detect the jumper wire. There is an open circuit in the wiring between the relay and the ECM connector. There may be a problem with a connector.
Repair: Repair the appropriate harness wiring or replace the appropriate harness.
Verify that the problem is resolved.

STOP
A -6 code became active during the override. The ECM detected the jumper wire. There is a problem with the solenoid. -
Repair: Replace the relay.
Verify that the problem is resolved.

STOP

Test Step 3. Check the Wiring for a Short Circuit

Verify that the harness connectors are free of debris, free of corrosion and securely connected.
Disconnect the harness from the relay.
Clear the -6 code.
Activate the override for the suspect circuit. Refer to table 2 for the appropriate override for the code.

Results:

A -6 code became active during the override. - The ECM did not detect the open circuit. There is a short circuit in the wiring between the relay and the ECM connector. There may be a problem with a connector.
Repair: Repair the appropriate harness wiring or replace the appropriate harness.
Verify that the problem is resolved.

STOP
A -5 code became active during the override. - The ECM detected the open circuit. The wiring is OK. The solenoid has a short circuit.
Repair: Replace the relay.
Verify that the problem is resolved.

STOP