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

Four Wheel Drive (4WD) Systems - Electronic Shift

Pinpoint Tests

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

Refer to Wiring Diagram Set 34, Four-Wheel Drive Systems for schematic and connector information. Diagrams By Number

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 N: 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: 4H (4X4 HIGH) or 4L (4X4 LOW) is not intended for driving on hard/dry surfaces.

NOTE: Make sure both CVH dials are in the same position.

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N1 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; 4H/4L is not intended for driving on hard/dry surfaces).
- Is excessive wind up present?

Yes
GO to N2.

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

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N2 CHECK FOR MATCHING WHEEL AND TIRE SIZES

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

Yes
GO to N3.

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

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N3 CHECK TIRE WEAR

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

Yes
GO to N4.

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

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N4 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 N5.

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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N5 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 VC. INSTALL the correct axle(s). REFER to Driveline System - General Information Description and Operation.

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