Pinpoint Test Y: Vehicle Pulsates or Shudders in a Straight Line (Straightline Driveline Wind-up)

Four Wheel Drive (4WD) Systems - Electronic Shift

Pinpoint Tests

Pinpoint Test Y: Vehicle Pulsates or Shudders in a Straight Line (Straightline Driveline Wind-up)

Normal Operation

In order for the Four-Wheel Drive (4WD) system to function correctly, tires and wheels must be the same size, be in good condition and the front and rear axle ratios must match.

This pinpoint test is intended to diagnose the following:
- Unmatched and wheel size
- Unequal amounts of tire wear
- Unequal tire inflation pressures
- Unmatched front and rear axle ratios

PINPOINT TEST Y: VEHICLE PULSATES OR SHUDDERS IN A STRAIGHT LINE (STRAIGHTLINE DRIVELINE WIND-UP)

WARNING: When directed to drive the vehicle as part of this test, drive the vehicle on a hard surface in an area without traffic to prevent a crash. Failure to follow these instructions may result in personal injury.

NOTE: 4X4 high/low (4H/4L) is not intended for driving on hard/dry surfaces.

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Y1 VERIFY THE CONCERN

- Drive the vehicle and shift from 2H to 4H. There should be minimal wind-up in 4H mode during straight line maneuvers (wind-up in turns is normal; 4X4 high/low is not intended for driving on hard/dry surfaces).
- Is excessive wind-up present?

Yes
GO to Y2.

No
RETURN the vehicle to the customer. ADVISE about correct 4WD system operation and normal vehicle behavior.

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Y2 CHECK FOR MATCHING WHEEL AND TIRE SIZES

- Check the wheel and tire sizes.
- Do the 4 wheel and tire sizes match?

Yes
GO to Y3.

No
ADVISE the customer that 4WD systems require 4 matched, correctly inflated, correctly maintained tires to operate correctly.

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Y3 CHECK TIRE WEAR

- Check each of the 4 tires for wear.
- Are the 4 tires worn evenly?

Yes
GO to Y4.

No
ADVISE the customer that 4WD systems require 4 matched, correctly inflated, correctly maintained tires to operate correctly.

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Y4 CHECK TIRE INFLATION PRESSURE

- Check the inflation pressure in each tire. Refer to Vehicle Certification (VC) label.
- Are the tire inflation pressures correct?

Yes
GO to Y5.

No
ADJUST the tire pressure as necessary. TEST the vehicle for normal operation. ADVISE the customer that 4WD systems require 4 matched, correctly inflated, correctly maintained tires to operate correctly.

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Y5 CHECK THE FRONT AND REAR AXLE RATIOS

- Check that front and rear axle ratios match. Refer to Driveline System - General Information Description and Operation.
- Do the front and rear axle ratios match?

Yes
RETURN the vehicle to the customer and ADVISE about correct 4WD usage and normal vehicle behavior.

No
CHECK the vehicle VC. INSTALL the correct axle(s). REFER to Driveline System - General Information Description and Operation.

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