PRODUCT SUPPORT PROGRAM FOR REPLACING THE ALL WHEEL STEERING SENSOR ON CERTAIN 434F2 AND 444F2 BACKHOE LOADERS Caterpillar

PRODUCT SUPPORT PROGRAM FOR REPLACING THE ALL WHEEL STEERING SENSOR ON CERTAIN 434F2 AND 444F2 BACKHOE LOADERS

Usage:

TEBE8708-00

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13Mar2019

U-127

A-99

D-103

O-107

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After Failure Only	PRODUCT SUPPORT PROGRAM FOR REPLACING THE ALL WHEEL STEERING SENSOR ON CERTAIN 434F2 AND 444F2 BACKHOE LOADERS
4303		PS54003

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NOTE:	Caterpillar’s obligations under this Service Letter are subject to, and shall not apply in contravention of, the laws, rules, regulations, directives, ordinances, orders, or statutes of the United States, or of any other applicable jurisdiction, without recourse or liability with respect to Caterpillar.
NOTE:	This Program can only be administered after a failure occurs. The decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS54003" as the Part Number and "7755" as the Group Number. Use "96" as the Warranty Claim Description Code and use "Z" as the SIMS Description Code.

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NOTE:

The information supplied in this service letter may not be valid after the termination date of this program. Do not perform the work outlined in this Service Letter after the termination date without first contacting your Caterpillar product analyst.

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TERMINATION DATE

31Mar2021

PROBLEM

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The existing axle steering position sensor can fail on certain 434F2 and 444F2 Backhoe Loaders. If the existing sensor fails, it can stop the steering mode from being changed.

Note: The sensors on the axle align the steering only once during a change in steer mode. The sensors are not a dynamic check and will not correct any drift in the steering system. If the customer is complaining about drift and they have not changed steering mode for some time, then the steering sensors are probably not at fault. Steering drift is most likely to be normal oil leakage across the control valve, or a seal leaking in a steering cylinder.

AFFECTED PRODUCT

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Model	Identification Number
434F 2	HWR00150-00367, 369 LYK00150-00708, 40533
444F 2	HWS00150-00298, 301-726, 728-731 LYL00150-00554, 557

PARTS NEEDED

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Qty	Part Number	Description
2	4417295	KIT-SENSOR
In order to allow equitable parts availability to all participating dealers, please limit your initial parts order to not exceed 3% of dealership population. This is an initial order recommendation only, and the ultimate responsibility for ordering the total number of parts needed to satisfy the program lies with the dealer.

ACTION REQUIRED

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Refer to the attached troubleshooting and Rework Procedure.

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SERVICE CLAIM ALLOWANCES

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Product smu/age whichever comes first	Caterpillar		Dealer Suggested		Customer Suggested
Product smu/age whichever comes first	Parts %	Labor Hrs%	Parts %	Labor Hrs%	Parts %	Labor Hrs%
0-3000 hrs, 0-24 mo	100.0%	100.0%	0.0%	0.0%	0.0%	0.0%

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NOTE: This is a 2.0-hour job

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PARTS DISPOSITION

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Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.

Rework Procedure

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Inspect the sensors for water intrusion. If there are signs of water intrusion, replace both the front and rear sensors.

Note: Some sensors have taken on water, but once dry, the sensors may start to work again as intended, leaving logged codes.

1. Steer from left to right and back again slowly and check whether any new diagnostic codes appear.

a. A newly logged/active diagnostic code relating to the axle sensors should be investigated to determine whether the sensor is faulty or whether the wiring between the ECM and the sensor has a fault. Refer to the following steps.

2. Check the 12 volt power and ground supply to the front and rear steering sensors.

a. 12 volts should be seen across sensor pins 1 and 4 at both sensors with the ignition key on and the engine off.

3. Check the LED function of the front and rear steering sensors with the ignition key on and the engine off. Refer to the following guide for LED status.

- LED ON - Sensor detects the cylinder in center position
- LED OFF - Sensor does not detect the cylinder in the center position
- LED Fast Flash - Calibration mode (15 seconds)
- LED Slow Flash - Sensor is energized but the calibration was unsuccessful
- LED 7 Fast Flashes Followed By 1 Long Pause - FLASH memory sector contains no valid data

a. If one (or both) of the sensor LEDs are slowly flashing, try to recalibrate the sensor. If you have already recalibrated the sensor on a previous repair, document your attempt to repair and replace both front and rear axle sensors.

b. If one (or both) of the sensor LEDs are giving 7 fast flashes followed by 1 long pause, document your findings and replace both front and rear axle sensors.

4. Check if the rear sensor detects axle center position.

a. With the machine in AWS mode, steer fully to the left so the axle is not centered.

b. Use an electrical spoon or equivalent to measure voltage between sensor pin 2 and chassis ground.

c. Slowly steer fully to the right to cross the center position.

- Sensor should read 12 volts when the axle is not centered.
- Sensor should read 0 volts when the axle is centered.

d. Use an electrical spoon or equivalent to measure voltage between sensor pin 3 and chassis ground.

e. Slowly steer fully to the left to cross the center position.

- Sensor should read 0 volts when the axle is not centered.
- Sensor should read 12 volts when the axle is centered

Repeat the process for the front steering sensor.

5. Check for AWS-related diagnostic codes using Cat? ET.

a. No new logged/active AWS-related diagnostic codes:

- If the recorded voltages in Steps 7 and 8 are incorrect, then there may be a problem with the sensor's ability to detect the center position. Proceed to recalibrate the sensor. If the problem occurs after recalibration, replace both the front and rear axle steering sensors.

- If the recorded voltages in Steps 7 and 8 are correct, then the steering sensor circuit is functioning normally. Any problems are related to another part of the AWS system.

b. New logged/active AWS-related diagnostic codes:

- If the recorded voltages in Steps 7 and 8 are correct, then there is a problem with the wiring or connectors between the sensor and the AWS ECM. Ensure they are not contaminated with water and check for any other signs of damage.

- If the recorded voltages in Steps 7 and 8 are incorrect, then there is a problem with the sensor. Replace both the front and rear steering sensors.

Note: Even if only one sensor is at fault, we recommend to replace both the FRONT and REAR sensors at this time.