3176C Engine for Caterpillar Built Machines Caterpillar

The ether injection system will improve cold weather starting of the engine. The ECM controls the ether injection system. The ether injection system has two operating modes. The ether injection system can operate in automatic mode and in manual mode. The engine oil temperature and the engine speed (rpm) are used to determine ether injection. The ether injection system is disabled if there is an active engine shutdown.

In the automatic mode, the ether injection system is enabled when all of the following conditions occur:

• Coolant temperature is less than 0 °C (32 °F).

• Inlet air temperature is less than 0 °C (32 °F).

• Engine speed (rpm) is between 35 rpm and 500 rpm.

In the automatic mode, the ECM energizes the relay for the ether in cycles of six seconds. The ether is turned ON for three seconds. The ether is then turned OFF for three seconds.

Manual mode is activated by pressing the starting aid switch. In the manual mode, the ether injection system is enabled when all of the following conditions are met:

• The starting aid switch is placed in the MANUAL position.

• Coolant temperature is less than 0 °C (32 °F).

• Inlet air temperature is less than 0 °C (32 °F).

• Engine speed (rpm) is between 35 rpm and 1200 rpm.

In manual mode, when the starting aid switch is depressed one 6 cc (0.3661 in³) shot of ether is injected.

In manual mode, ether injection is disabled if engine speed (rpm) is greater than 1200 rpm. In manual mode, ether injection is also disabled if coolant temperature is greater than 10 °C (50 °F).

Illustration 1	g00889743
Schematic for ether injection

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Breathing ether vapors or repeated contact of ether with skin can cause personal injury. Personal injury may occur from failure to adhere to the following procedures. Use ether only in well ventilated areas. Do not smoke while changing ether cylinders. Use ether with care to avoid fires. Do not store replacement ether cylinders in living areas or in the operator's compartment. Do not store ether cylinders in direct sunlight or at temperatures above 49 °C (120 °F). Discard cylinders in a safe place. Do not puncture or burn cylinders. Keep ether cylinders out of the reach of unauthorized personnel. To avoid possible injury, be sure the brakes are applied and all controls are in Hold or Neutral when starting the engine.

Test Step 1. Inspect Electrical Connectors and Wiring

1. Turn the keyswitch to the OFF/RESET position.

2. Thoroughly inspect ECM connector J1/P1, machine connector J3/P3, and all other connectors in the wiring harness. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

3. Inspect the following components for damage, corrosion, and incorrect attachment:
   • battery posts

   • alternator

   • breaker

   • engine ground

   • machine ground

Expected Result:

All connectors, pins, and sockets should be completely inserted and coupled. The harness and wiring should be free of corrosion, abrasion, and pinch points. All connections and grounds should be tight and free of corrosion.

Results:

• OK - Proceed to Test Step 2.

• Not OK -

  Repair: Repair the circuit.Verify that the repair eliminates the problem.

  Stop.

Test Step 2. Check the Starting Aid Switch Status on the Caterpillar Electronic Technician (Cat ET)

1. Remove the ether canister from the starting aid solenoid.

2. Connect Cat ET to the service tool connector.

3. Turn the keyswitch to the ON position.

4. Press the starting aid switch to "MANUAL". Observe the "Starting Aid Switch Status" on Cat ET.

Expected Result:

When the starting aid switch is pressed, Cat ET should display the status of the starting aid switch as ON.

When the starting aid switch is not pressed, Cat ET should display the status of the starting aid switch as OFF.

Results:

• OK - The starting aid switch is operating correctly. Proceed to Test Step 6.

• Not OK - The ECM is not properly reading the signal from the starting aid switch. Proceed to Test Step 3.

Test Step 3. Check the Resistance of the Relay

Illustration 2	g00794643
Connector for the starting aid relay

1. Turn the keyswitch to the OFF/RESET position.

2. Measure the resistance across terminal 85 (solenoid return) and terminal 86 (Ether On).

Expected Result:

The resistance should be between 250 Ohms and 500 Ohms.

Results:

• OK - Proceed to Test Step 4.

• Not OK - The relay is faulty.

  Repair: Replace the relay.Verify that the repair eliminates the problem.

  Stop.

Test Step 4. Short the Switch Wires

1. Remove wire R974-OR (Starting Aid Switch) and wire L901-GY (Digital Return) from the starting aid switch.

2. Short wire R974-OR (Starting Aid Switch) to wire L901-GY (Digital Return).

Expected Result:

When the wires are shorted, Cat ET should display the status of the starting aid switch as ON.

When the wires are not shorted, Cat ET should display the status of the starting aid switch as OFF.

Results:

• OK - The starting aid switch is not operating correctly.

  Repair: Replace the starting aid switch.Verify that the repair eliminates the problem.

  Stop.

• Not OK - The starting aid switch is operating correctly. Proceed to Test Step 5.

Test Step 5. Short the Switch Inputs at the ECM

Illustration 3	g00794674
ECM connector P1 (wire side)

1. Turn the keyswitch to the OFF position.

2. Remove the wire from terminals P1:22 (Starting Aid Switch) and P1:18 (Digital Return).

3. Turn the keyswitch to the ON position.

4. Observe the status of "Ether Switch" on Cat ET.

5. Turn the keyswitch to the OFF/RESET position.

6. Make a jumper wire with a Deutsch pin at each end of the wire.

7. Install the jumper wire between P1:22 (Starting Aid Switch) and P1:18 (Digital Return).

8. Turn the keyswitch to the ON position.

9. Observe the status of "Ether Switch" on Cat ET.

10. Remove the jumper and reinstall the wires in the P1 connector.

Expected Result:

When the wires are shorted, Cat ET should display the status of the starting aid switch as "ON".

When the wires are not shorted, Cat ET should display the status of the starting aid switch as "OFF".

Results:

• OK - There is a problem in the wiring between the switch and the ECM.

  Repair: Repair the circuit.Verify that the repair eliminates the problem.

  Stop.

• Not OK - The ECM is not reading the switch input properly.

  Repair: Verify your results. Replace the ECM. Refer to Troubleshooting, "Replacing the ECM" before replacing the ECM.Verify that the repair eliminates the problem.

  Stop.

Test Step 6. Check the Resistance of the Starting Aid Solenoid

1. Disconnect connector J504/P504 (Starting Aid Solenoid connector).

2. Measure the resistance between J504:1 (Solenoid Power) and J504:2 (Solenoid Return).

Expected Result:

Resistance should be less than 10 Ohms.

Results:

• OK - Proceed to Test Step 7.

• Not OK - The starting aid solenoid is faulty.

  Repair: Replace the ether solenoid.Verify that the repair eliminates the problem.

  Stop.

Test Step 7. Check the Supply Voltage to The Starting Aid Solenoid

Note: The ether canister must be removed prior to activating this test.

1. Turn the keyswitch to the ON position.

2. Proceed to the "Diagnostic Override Screen" in Cat ET.

3. Activate the ether injection system.

   Note: The diagnostic override will only activate the starting aid relay for 3 seconds.

4. Use signal reading probes to measure the voltage between J504:1 (Solenoid Power) and J504:2 (Solenoid Return) when the ether injection system is activated.

Expected Result:

The supply voltage should be greater than 22.0 VDC.

Results:

• OK - The ECM is properly controlling the Ether Injection System. Proceed to Test Step 8.

• Not OK - The starting aid solenoid is not receiving the correct signal. Proceed to Test Step 9.

Test Step 8. Check for Correct Operation of the Starting Aid Solenoid

Note: The ether canister must be removed prior to activating this test.

1. Turn the keyswitch to the ON position.

2. Proceed to the "Diagnostic Override Screen" in Cat ET.

3. Activate the ether injection system.

   Note: The diagnostic override will only activate the starting aid relay for 3 seconds.

4. Listen for an audible click as the starting aid solenoid is activated. Listen for an audible click as the starting aid solenoid is deactivated.

Expected Result:

A click is heard.

Results:

• OK - The ether injection system is operating correctly. Stop.

• Not OK - The starting aid solenoid is faulty.

  Repair: Replace the starting aid solenoid.Verify that the repair eliminates the problem.

  Stop.

Test Step 9. Check the Voltage at the Starting Aid Relay

Illustration 4	g00794643
Connector for the starting aid relay

Note: The ether canister must be removed prior to activating this test.

1. Ensure that all connectors are connected to the wiring harness.

2. Turn the keyswitch to the ON position.

3. Proceed to the "Diagnostic Override Screen" in Cat ET.

4. Activate the ether injection system.

   Note: The diagnostic override will only activate the starting aid relay for 3 seconds.

5. Measure the voltage across terminal 85 (Solenoid Return) and terminal 86 (Ether ON) of the starting aid relay.

Expected Result:

The voltage should be 24.0 ± 8.0 VDC.

Results:

• OK - Proceed to Test Step 10.

• Not OK - Proceed to Test Step 12.

Test Step 10. Check the Output Voltage of the Starting Aid Relay

Illustration 5	g00794643
Connector for the starting aid relay

Note: The ether canister must be removed prior to activating this test.

1. Ensure that all connectors are connected to the wiring harness.

2. Turn the keyswitch to the ON position.

3. Proceed to the "Diagnostic Override Screen" in Cat ET.

4. Activate the ether injection system.

   Note: The diagnostic override will only activate the starting aid relay for 3 seconds.

5. Measure the voltage across terminal 85 (Solenoid Return) and terminal 30 (Solenoid Power) of the starting aid relay.

Expected Result:

The voltage should be 24.0 ± 8.0 VDC.

Results:

• OK - There is a problem in the wiring between the starting aid relay and the starting aid solenoid.

  Repair: Repair the circuit.Verify that the repair eliminates the problem.

  Stop.

• Not OK - Proceed to Test Step 11.

Test Step 11. Check the Power Supply to the Starting Aid Relay

Illustration 6	g00794643
Connector for the starting aid relay

1. Measure the voltage across terminal 87 (+Battery) and chassis ground.

Expected Result:

The voltage should be 24.0 ± 8.0 VDC.

Results:

• OK - The starting aid relay is faulty.

  Repair: Replace the starting aid relay.Verify that the repair eliminates the problem.

  Stop.

• Not OK - There is a problem in the wiring between the starting aid relay and the +Battery terminal.

  Repair: Repair the circuit.Verify that the repair eliminates the problem.

  Stop.

Test Step 12. Check for Shorts in the Wiring Harness from the Starting Aid Relay to the ECM

Illustration 7	g00759787
ECM connector P1

1. Disconnect ECM connector J1/P1.

2. Disconnect the plug for the starting aid relay.

3. Measure the resistance between P1:21 (Starting Aid Relay) and engine ground.

Expected Result:

The resistance should be greater than 20,000 Ohms.

Results:

• OK - Proceed to Test Step 13.

• Not OK - There is a short between the ECM and the starting aid relay.

  Repair: Repair the circuit.

  Stop.

Test Step 13. Check the Voltage for the Starting Aid Relay at the ECM

Illustration 8	g00728246
ECM connector P1 (wire side)

Note: The ether canister must be removed prior to activating this test.

1. Turn the keyswitch to the OFF position.

2. Remove the wire from P1:21 (Starting Aid Relay) in ECM connector P1.

3. Turn the keyswitch to the ON position.

4. Proceed to the "Diagnostic Override Screen" in Cat ET.

5. Activate the ether injection system.

   Note: The diagnostic override will only activate the starting aid relay for 3 seconds.

6. Measure the voltage between P1:21 (Starting Aid Relay) and engine ground.

7. Turn the keyswitch to the OFF/RESET position. Replace the wire to P1:21 (Starting Aid Relay).

Expected Result:

The voltage should be 24.0 ± 8.0 VDC.

Results:

• OK - The ECM is supplying the correct voltage. There may be an open circuit or a short circuit in the harness.

  Repair: Repair the circuit.Verify that the repair eliminates the problem.

  Stop.

• Not OK - The ECM is not supplying the correct voltage.

  Repair: Verify your results. Replace the ECM. Refer to Troubleshooting, "Replacing the ECM" before replacing the ECM.Verify that the repair eliminates the problem.

  Stop.