Manufacturer communication — 2006 GMC YUKON DENALI

• Applies to 2003-2006 GMC Yukon, Yukon Denali and Yukon XL, and to the 2007-2013 GMC Yukon XL 2500 Series only, among other listed GM trucks and vans.

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  2003-2006 GMC Yukon, Yukon Denali, Yukon XL 2003-2007 GMC Sierra Classic 2003-2013 GMC Savana 2500-4500 Series Only 2007-2010 GMC Sierra 2500-3500 Series Only 2007-2013 GMC Yukon XL 2500 Series Only

• In rare cases customers report a lack of steering assist when stopped or during parking lot type maneuvers, which can occur when the brakes are applied and the steering wheel is turned with the vehicle stopped.

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  In rare cases, customers may comment on a lack of steering assist when stopped or during parking lot type maneuvers. A lack of steering assist could occur if the brakes are applied and turning the steering wheel with the vehicle stopped or during parking lot type maneuvers.

• The condition goes away or greatly improves once the vehicle begins to move or is above parking lot speeds.

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  This condition will go away or greatly improve once the vehicle begins to move or is above parking lot speeds.

Possible causes

• The concern can be aggravated by worn tires, low tire air pressure, low power steering pump pressures, and tires larger than stock size.

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  This concern can be aggravated by worn tires, low tire air pressure, low power steering pump pressures, and tires larger than stock size.

Steps to confirm (in the document’s order)

1. In all cases set the proper tire size and the maximum tire pressure per the manufacturer's specification on the door placard, especially for the front tires.

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   In all cases, it is recommended that the proper tire size and the maximum tire pressure is set according to the manufacturer’s specification as noted on the door placard; especially for the front tires.

2. Perform the "Power Steering System Test" found in SI and make any necessary repairs based on system diagnosis.

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   Perform the "Power Steering System Test" found in SI. Make any necessary repairs based on system diagnosis.

3. To tell whether the vehicle has a 670 gear box, inspect the mounting bolts that attach the stub shaft housing; if the housing has no mounting bolts or has 4 bolts, do not proceed, as the vehicle does not have a 670 gear box.

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   To determine if the vehicle is equipped with a 670 gear box, inspect the mounting bolts that attach the stub shaft housing. A 670 gear box will only have mounting bolts. If the stub shaft housing does not have any mounting bolts or has 4 bolts - DO NOT PROCEED WITH THIS BULLETIN. The vehicle is not equipped with a 670 gear box.

Repair

1. If a C/K 1500 Series vehicle has a 670 gear box, replacing it with a 680 gear box may increase customer satisfaction.

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   If a C/K 1500 Series vehicle is equipped with a 670 gear box, replacing it with a 680 gear box may increase the customer satisfaction.

2. When replacing a 670 gear box with a 680 gear box, replace the power steering gear, the union fitting and both inlet O-ring seals.

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   If replacing a 670 gear box with a 680 gear box, it will be necessary to replace the power steering gear, union fitting and both inlet O-ring seals.

Parts

• Parts for C/K 1500 Series only: 88965542 Power Steering Gear, 26025709 Union Fitting, 26001594 Inlet O-ring Seal.

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  Parts Information (C/K 1500 Series Only) Part Number Description 88965542 Power Steering Gear 26025709 Union Fitting 26001594 Inlet O-ring Seal

Caution

• For C/K 1500 series vehicles, if diagnostics did not lead to any repair, the concern is a normal operating characteristic.

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  FOR C/K 1500 SERIES VEHICLES ONLY - If diagnostics did not lead to any repair, this concern is a normal operating characteristic.