Pinpoint Test E: Vehicle Pulsates or Shudders in a Straight Line (Straight Line Driveline Wind Up)

Four Wheel Drive (4WD) Systems - Mechanical Shift

Pinpoint Tests

Pinpoint Test E: Vehicle Pulsates or Shudders in a Straight Line (Straight Line 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 tire sizes
- Unequal amounts of tire wear
- Unequal tire inflation pressures
- Unmatched front and rear axle ratios
- Front and rear axles

PINPOINT TEST E: VEHICLE PULSATES OR SHUDDERS IN A STRAIGHT LINE (STRAIGHT LINE 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.

NOTICE: Vehicles equipped with the Manual Shift-On-Stop (MSOS) system and manual hublocks should not be operated in 4H or 4L mode with the hublocks set to the FREE position. Doing so can result in damage to driveline components.

NOTE: 4H (4X4 HIGH) and 4L (4X4 LOW) are not intended for driving on hard/dry surfaces.

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E1 VERIFY THE CONCERN

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

Yes
GO to E2.

No
RETURN the vehicle to the customer and ADVISE about correct Four-Wheel Drive (4WD) usage and normal vehicle behavior.

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E2 CHECK FOR MATCHING WHEEL AND TIRE SIZES

- Check each of the 4 tire/wheel sizes.
- Do the 4 wheels and tires match?

Yes
GO to E3.

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

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E3 CHECK TIRE WEAR

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

Yes
GO to E4.

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

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E4 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 E5.

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

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E5 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 system operation and normal vehicle behavior.

No
CHECK the vehicle identification label. INSTALL the correct axle(s).

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