AP-655C and BG-2255C Asphalt Pavers Propel System Caterpillar

Testing and Adjusting the Position Sensor for the Steering Wheel

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Do not operate or work on this machine unless you have read and understand the instructions and warnings in the Operation and Maintenance Manual. Failure to follow the instructions or heed the warnings could result in injury or death. Contact any Caterpillar dealer for replacement manuals. Proper care is your responsibility.

Introduction

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Operator Console

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The position sensor (steering) is located directly behind the steering wheel in the operator station.

The sensor for the steering wheel generates a PWM signal. The duty cycle will vary with movement of the steering wheel. The electronic control module (ECM) receives the PWM signal from the sensor. In addition, the ECM provides battery voltage to the sensor. As the signal is sent to the ECM, the ECM reads the duty cycle. The ECM then controls the amount of electrical current to the (EDC) electronic displacement control on the propel pump.

Required Tools

Hydraulic test procedures may be performed using either one of the following test equipment:

• Caterpillar DataView

• Standard Multimeter

Caterpillar DataView Tool

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Caterpillar DataView Caterpillar DataView is a PC based diagnostic tool. The Caterpillar DataView accepts a maximum of nine standard Caterpillar sensors for measurements on the machine. The signal is transmitted to a personal computer and the information is displayed.

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Caterpillar DataView Electrical Test Group

The following table provides a list of the required tools if Caterpillar DataView is used in order to perform the following test procedure. Caterpillar DataView is not shown in the following test procedure.

Standard Tools

There are various tools that may be used in order to test the PWM signal or the duty cycle of the position sensor. A few of the tools are listed below.

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Digital Multimeter Group

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Fluke Multimeter

Test Procedure

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Sudden movement of the machine or release of oil under pressure can cause serious injury to persons on or near the machine. To prevent possible injury, perform the procedure that follows before testing and adjusting the hydraulic system.

Perform the following procedure before you perform the test procedure that follows:

• Park the machine on a level area that is clear from all equipment, material, and personnel.

• Verify that the service brake system and the parking brake system are in good working order.

• Apply the parking brake.

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1. Locate the main console on the machine. The main console is located directly in the center of the two operator stations.

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2. Loosen the two screws on the door of the main console.

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Main Console

3. Locate "J1" connector (1) on the electronic control module (ECM) in the center main console.

4. Ensure that the engine start switch is turned to the OFF position.

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5. Connect the ground clip on multimeter (A1) to the ground post or one of the mounting bolts.

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ECM inside Main Console (1) J1 Connector (2) "Pin 16"

Note: The position sensor for the left steering wheel and the position sensor for the right steering wheel are connected into "Pin 16".

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6. Insert one of the spoons or probes on multimeter (A1) into "Pin 16" (2) on "J1" connector (1) .

7. Ensure that the multimeter is set at % or the setting for the duty cycle.

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Main Console

8. Turn the engine start switch to the ON position. Do not start the engine.

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9. Leave the steering wheel in the CENTER position. Multimeter (A1) shoudl have a duty cylcle reading of 50% ± 3%. If the duty cycle reading is not within these limits, an adjustment needs to be made.

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Left Rotation of Steering Wheel

10. Slowly turn the steering wheel to the maximum LEFT position and observe the duty cycle reading as you turn the wheel. The duty cycle should decrease until the steering wheel is in the maximum LEFT position. At the maximum LEFT position, multimeter (A1) should have a duty cycle reading of 10% ± 3%. If duty cycle fluctuates as you turn the sensor, replace the sensor. If the duty cycle reading is not within these limts, an adjustment needs to be made.

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Right Rotation of Steering Wheel

11. Slowly turn the steering wheel to the maximum RIGHT position and observe the duty cycle reading as you turn the wheel. The duty cycle should increase until the steering wheel is in the maximum RIGHT position. At the maximum RIGHT position, multimeter (A1) should have a duty cycle reading of 90% ± 3%. If duty cycle fluctuates as you turn the sensor, replace the sensor. If the duty cycle reading is not within these limts, an adjustment needs to be made.

12. Leave the test equipment in place as you adjust the sensor.

Adjustment Procedure

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Main Console

Note: Select the left operator station first. Proceed with the adjustment or replacement. Proceed to check the right operator station. Each station must be retested independently. Use the operator select switch on the main console in order to switch the operator stations.

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Left Operator Station

1. Loosen the screws. Remove the panel below the operator station.

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Top View of the Machine

2. Loosen the screws. Remove the panels on the front operator station.

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(1) Position sensor (2) Steering wheel

3. Locate position sensor (1) on the back of the steering wheel (2) .

4. Loosen the two mounting screws. Rotate position sensor (1) until the mark on the sensor and the mark on the housing are aligned.

5. Retest the sensor. Multimeter (A1) should have a duty cycle reading of 50% ± 3% when you leave the steering wheel in the CENTER position. When you slowly turn the steering wheel to the maximum LEFT position, the duty cycle reading should slowly decrease and as you reach the maximum LEFT position, the duty cycle reading should be 10% ± 3%. When you slowly turn the steering wheel to the maximum RIGHT position, the duty cycle reading should slowly increase and as you reach the maximum RIGHT position, the duty cycle reading should be 90% ± 3%. Adjust the sensor and retest the sensor until the duty cycle readings are within these limits.

6. Tighten the mounting screws on position sensor (1) .

7. If a reading of 10% to 90% could not be obtained, replace the sensor. If necessary, repeat the procedure for the other operator station.

8. Replace the panels on the operator station.

9. Tighten the two screws on the main console.

10. Turn the engine start switch to the OFF position.

11. Remove the tooling.