3176C Engine for Caterpillar Built Machines Caterpillar

Travel Alarm System - Test

Usage:

System Operation Description:

The travel alarm provides an audible signal in order to indicate machine travel. The system for the travel alarm consists of the following components:

Travel alarm cancel switch
Travel pressure switch
Travel alarm relay

The travel pressure switch is an input to the ECM. The travel pressure switch closes when the machine starts to travel. The ECM energizes the travel alarm relay. The relay activates the travel alarm. The alarm will remain on until one of the following conditions have been met:

The machine is no longer travelling.
"Travel Alarm On Time" has elapsed and the operator has pushed the travel alarm cancel switch.

Note: The travel alarm cannot be shut off until the "Travel Alarm On Time" has elapsed. If the travel alarm cancel switch is pressed prior to the "Travel Alarm On Time" timing out, the travel alarm will remain on until the "Travel Alarm On Time" has elapsed. When the "Travel Alarm On Time" has elapsed, the travel alarm will deactivate.

Show/hide table




Illustration 1	g00889998
Schematic for the travel alarm

Test Step 1. Test the System for the Travel Alarm

Turn the keyswitch to the ON position.

Proceed to the "Diagnostic Override Screen" in Caterpillar Electronic Technician (Cat ET).

Activate the "Travel Alarm Override".

The travel alarm should be audible when the override is active. If the travel alarm sounds, wait for a few seconds and then press the travel alarm cancel switch.

Expected Result:

The travel alarm activates when the "Travel Alarm Override" is activated. The travel alarm deactivates when the travel alarm cancel switch is pressed.

Results:

OK - The travel alarm appears to be operating correctly. Proceed to Test Step 2.
Not OK - The travel alarm does not emit an alarm. Proceed to Test Step 2.
Not OK - The travel alarm activates but the travel alarm does not deactivate when the travel alarm cancel switch is pressed. Proceed to Test Step 13.

Test Step 2. Inspect Electrical Connectors and Wiring

Turn the keyswitch to the OFF/RESET position.

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.

Inspect the following components for damage, corrosion, and incorrect attachment:
- Battery posts
- 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 3.
Not OK -
Repair: Repair the circuit.Verify that the repair eliminates the problem.
Stop.

Test Step 3. Check the "Travel Pilot Pressure Switch" Status on Cat ET

Show/hide table

Personal injury or death can result from sudden machine movement.
Sudden movement of the machine can cause injury to persons on or near the machine.

To prevent injury or death, make sure that the area around the machine is clear of personnel and obstructions before operating the machine.

Connect Cat ET to the service tool connector.

Start the engine.

Monitor "Status Screen 5" on Cat ET. Observe the "Travel Pilot Pressure Switch" status. Drive the machine for a short distance.

Expected Result:

When the machine is travelling, Cat ET should display the status of the travel pressure switch as ON.

When the machine is stationary, Cat ET should display the status of the travel pressure switch as OFF.

Results:

OK - The travel pressure switch is operating correctly. Proceed to Test Step 7.
Not OK - The ECM is not properly reading the signal from the travel pressure switch. Proceed to Test Step 4.

Test Step 4. Check the Resistance of the Relay

Show/hide table




Illustration 2	g00795307
Connector for the travel alarm relay

Turn the keyswitch to the OFF/RESET position.

Measure the resistance across terminal 85 (-Battery) and terminal 86 (Travel Alarm Enable).

Expected Result:

The resistance should be between 250 Ohms and 500 Ohms.

Results:

OK - Proceed to Test Step 5.
Not OK - The relay is faulty.
Repair: Replace the relay.Verify that the repair eliminates the problem.
Stop.

Test Step 5. Short the Switch Wires

Remove wire C978-BR (Travel Pressure Switch) and wire L901-GY (Digital Return) from the travel pressure switch.

Short wire C978-BR (Travel Pressure Switch) to wire L901-GY (Digital Return).

Expected Result:

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

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

Results:

OK - The travel pressure switch is not operating correctly.
Repair: Replace the travel pressure switch.Verify that the repair eliminates the problem.
Stop.
Not OK - The travel pressure switch is operating correctly. Proceed to Test Step 6.

Test Step 6. Short the Switch Inputs at the ECM

Show/hide table




Illustration 3	g00795340
ECM connector P1 (wire side)

Turn the keyswitch to the OFF position.

Remove the wire from terminals P1:46 (Travel Pressure) and P1:18 (Digital Return).

Turn the keyswitch to the ON position.

Observe the status of "Pilot Travel Pressure Switch" on Cat ET.

Turn the keyswitch to the OFF/RESET position.

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

Install the jumper wire between P1:46 (Travel Pressure) and P1:18 (Digital Return).

Turn the keyswitch to the ON position.

Observe the status of "Pilot Travel Pressure Switch" on Cat ET.

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 travel pressure switch as "ON".

When the wires are not shorted, Cat ET should display the status of the travel pressure 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 7. Check the Supply Voltage to The Travel Alarm

Turn the keyswitch to the ON position.

Proceed to the "Diagnostic Override Screen" in ET.

Activate the "Travel Alarm Override".

The travel alarm should be audible when the override is active. If the alarm is not audible, use signal reading probes to measure the voltage between the two connections on the travel alarm.

Expected Result:

The supply voltage should be greater than 22.0 VDC.

Results:

OK - The ECM is properly controlling the travel alarm. The travel alarm should be audible.
Repair: If the alarm is not audible, replace the travel alarm.Verify that the repair eliminates the problem.
Stop.
Not OK - The travel alarm is not receiving the correct signal. Proceed to Test Step 8.

Test Step 8. Check the Voltage at the Travel Alarm Relay

Show/hide table




Illustration 4	g00795307
Connector for the travel alarm relay

Ensure that all connectors are connected to the wiring harness.

Turn the keyswitch to the ON position.

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

Activate the "Travel Alarm Override".

Measure the voltage across terminal 85 (-Battery) and terminal 86 (Travel Alarm Enable) of the travel alarm relay.

Expected Result:

The voltage should be 24.0 ± 8.0 VDC.

Results:

OK - Proceed to Test Step 9.
Not OK - Proceed to Test Step 11.

Test Step 9. Check the Output Voltage of the Travel Alarm Relay

Show/hide table




Illustration 5	g00795307
Connector for the travel alarm relay

Ensure that all connectors are connected to the wiring harness.

Turn the keyswitch to the ON position.

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

Activate the "Travel Alarm Override".

Measure the voltage across terminal 85 (-Battery) and terminal 30 (Travel Alarm Power) of the travel alarm relay.

Expected Result:

The voltage should be 24.0 ± 8.0 VDC.

Results:

OK - There is a problem in the wiring between the travel alarm relay and the travel alarm.
Repair: Repair the circuit.Verify that the repair eliminates the problem.
Stop.
Not OK - Proceed to Test Step 10.

Test Step 10. Check the Power Supply to the Travel Alarm Relay

Show/hide table




Illustration 6	g00795307
Connector for the travel alarm relay

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

Expected Result:

The voltage should be 24.0 ± 8.0 VDC.

Results:

OK - The travel alarm relay is faulty.
Repair: Replace the travel alarm relay.Verify that the repair eliminates the problem.
Stop.
Not OK - There is a problem in the wiring between the travel alarm relay and the +battery terminal.
Repair: Repair the circuit.Verify that the repair eliminates the problem.
Stop.

Test Step 11. Check for Shorts in the Wiring Harness from the Travel Alarm Relay to the ECM

Show/hide table




Illustration 7	g00795708
ECM connector P1

Disconnect ECM connector J1/P1.

Disconnect the plug for the travel alarm relay.

Measure the resistance between P1:10 (Travel Alarm Enable) and engine ground.

Expected Result:

The resistance should be greater than 20,000 Ohms.

Results:

OK - Proceed to Test Step 12.
Not OK - There is a short between the ECM and the travel alarm relay.
Repair: Repair the circuit.
Stop.

Test Step 12. Check the Voltage for the Travel Alarm Relay at the ECM

Show/hide table




Illustration 8	g00795708
ECM connector J1/P1 (wire side)

Turn the keyswitch to the OFF position.

Remove the wire from P1:10 (Travel Alarm Enable) in ECM connector P1.

Turn the keyswitch to the ON position.

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

Activate the "Travel Alarm Override".

Measure the voltage between P1:10 (Travel Alarm Enable) and engine ground.

Turn the keyswitch to the OFF/RESET position. Replace the wire to P1:10 (Travel Alarm Enable).

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.

Test Step 13. Check the Travel Alarm Cancel Switch on Cat ET

Connect Cat ET to the service tool connector.

Turn the keyswitch to the ON position.

Press the travel alarm cancel switch. Observe the "Travel Alarm Cancel Cab Switch" status on Cat ET.

Expected Result:

When the travel alarm cancel switch is pressed, Cat ET should display the status of the switch as ON.

When the travel alarm cancel switch is pressed, Cat ET should display the status of the switch as OFF.

Results:

OK - The travel alarm cancel switch is operating correctly. Stop.
Not OK - The ECM is not properly reading the signal from the travel alarm cancel switch. Proceed to Test Step 14.

Test Step 14. Short the Switch Wires

Remove wire E703-WH (Travel Alarm Cancel Switch) and wire L901-GY (Digital Return) from the travel alarm cancel switch.

Short wire E703-WH (Travel Alarm Cancel Switch) to wire L901-GY (Digital Return).

Expected Result:

When the wires are shorted, Cat ET should display the status of the travel alarm cancel switch as ON.

When the wires are not shorted, Cat ET should display the status of the travel alarm cancel switch as OFF.

Results:

OK - The travel alarm cancel switch is not operating correctly.
Repair: Replace the travel alarm cancel switch.Verify that the repair eliminates the problem.
Stop.
Not OK - The travel alarm cancel switch is operating correctly. Proceed to Test Step 6.

Test Step 15. Short the Switch Inputs at the ECM

Show/hide table




Illustration 9	g00795672
ECM connector P1 (wire side)

Turn the keyswitch to the OFF position.

Remove the wire from terminals P1:47 (Travel Alarm Cancel) and P1:18 (Digital Return).

Turn the keyswitch to the ON position.

Observe the status of "Travel Alarm Cancel Cab Switch" on Cat ET.

Turn the keyswitch to the OFF/RESET position.

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

Install the jumper wire between P1:47 (Travel Alarm Cancel) and P1:18 (Digital Return).

Turn the keyswitch to the ON position.

Observe the status of "Travel Alarm Cancel Cab Switch" on Cat ET.

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 travel alarm cancel switch as "ON".

When the wires are not shorted, Cat ET should display the status of the travel alarm cancel 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.