1999 GMC Sierra 1500 TSBs

PARK / NEUTRAL POSITION SWITCH, USUALLY WHEN TRYING TO REMOVE THE SWITCH DURING TRANSMISSION SERVICE. *TT

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Technician should be advised that the maximum pinion shim to be used or stacked behind the pinion is 0.050?, and the minimum pinion shim is 0.020? for an 8.6 axle. The range for available pinion depth shims for the 10.5? axle is 0.006? to 0.024?. When setting the backlash it should be set between 0.003? to 0.005? on a new ring and pinion for any American Axle Manufacturing application. The ring and pinion can be reused or adjusted if the mileage is less than 500 miles, if not used for towing. Technician should be advised that a ?roller coaster? or ?hourglass? pattern on the bearings may be normal up to 10,000 miles and possibly longer. With a mis-machined housing you may get a heel pattern on both sides of the gear teeth at build up can generally be corrected with backlash adjustments. When setting up an 8.6? axle with a 5 cut gear set is to use a 0.035? pinion shim and set backlash to 0.004?. When using the newer 2 cut gear set also use a 0.035? pinion shim and still set backlash to 0.004?. To set the gear pattern use backlash to adjust the pattern heel to toe. Use the pinion shim to adjust the height of the pattern. The proper drive pinion bearing pre-load is from 15 - 30 inch pounds with new bearings. The total torque to turn after the differential case is installed should increase 5 - 10 inch pounds at the pinion. A new pinion nut must be used whenever the old one is removed. The axle shaft end play specification is 0.012? per side and the radial specification is 0.002? - 0.003?. Technician should be advised that synthetic lube can be used in all new American Axle Manufacturing axle assemblies. The new pinion seal for the 8.6? axle assembly is a two piece design.

protection or tint offered by the windshield or side glass. Technician should be advised Windshield reduces Ultraviolet rays down to 4% or less. Front side door glass reduces Ultraviolet rays down to 35% or less. Windshields are SOLAR glass with a light transmittance of >/=70%. Front door glass are Solar glass with a light transmission of >/=70%. Rear door glass, quarter windows and back windows can use either Solar glass (>/=70%) or Privacy glass, which has a light transmittance of 20%.

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GM does not endorse any repairs that involve welding, bending, straightening o re-machining. Only cosmetic refinishing of the wheel's coatings, using recommended procedures, is allowed. Evaluating Damage In evaluating damage, it is the GM Dealer's responsibility to inspect the wheel for corrosion, scrapes, gouges, etc. The Dealer must insure that such damage is not deeper than what can be sanded or polished off. The wheel must be inspected for cracks. If cracks are found, discard the wheel. Any wheels with bent rim flanges must not be repaired or refinished. Wheels that have been refinished by an outside company must be returned to the same vehicle. The Dealer must record the wheel ID stamp or the cast date on the wheel in order to assure this requirement. Refer to Refinisher's Responsibility Outside Company later in this bulletin.

GM does not endorse any repairs that involve welding, bending, straightening o re-machining. Only cosmetic refinishing of the wheel's coatings, using recommended procedures, is allowed. Evaluating Damage In evaluating damage, it is the GM Dealer's responsibility to inspect the wheel for corrosion, scrapes, gouges, etc. The Dealer must insure that such damage is not deeper than what can be sanded or polished off. The wheel must be inspected for cracks. If cracks are found, discard the wheel. Any wheels with bent rim flanges must not be repaired or refinished. Wheels that have been refinished by an outside company must be returned to the same vehicle. The Dealer must record the wheel ID stamp or the cast date on the wheel in order to assure this requirement. Refer to Refinisher's Responsibility Outside Company later in this bulletin.

or disable the Bi-Fuel Compressed Natural Gas system. General Motors does not condone the removal of the original equipped Compressed Natural Gas systems.

GMC ENGINEERING IS ATTEMPTING TO DETERMINE THE ROOT CAUSE OF THE ABOVE CONCERN. *PE

VEHICLES EXPOSED TO EXTREME OFF-ROAD CONDITIONS OR SNOW PLOWING ARE MORE PRONE TO DEVELOP THIS CONDITION. *TT

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to be replaced if the brake pedal moves or applies on its own at a full turn.

to be replaced if the brake pedal moves or applies on its own at a full turn.

TO BE REPLACED IF THE BRAKE PEDAL MOVES OR APPLIES ON ITS OWN AT A FULL TURN.

Some customers may comment that one or more of their vehicle's underbody components are showing some form of corrosion. This corrosion may be red in appearance (rust) if the component is steel, forged iron or cast iron. This corrosion may also be grey or white in color if the component is constructed of an aluminum alloy.

Some customers may comment that one or more of their vehicle's underbody components are showing some form of corrosion. This corrosion may be red in appearance (rust) if the component is steel, forged iron or cast iron. This corrosion may also be grey or white in color if the component is constructed of an aluminum alloy.

The customer communication requested return of unsold inventory to inspect for incorrect UPC. Incorrect UPC could lead to a discrepency of inventory at the store. Incorrect UPC would have no impact to the end user as it is a box labeling issue and doesn't impact the part itself.

Technician should not replace any parts for this concern. Please communicate to the customer this condition is a normal operating characteristic of their vehicle.

additive.

The customer communication requested return of unsold inventory to inspect for damage to the braided hose and crimps. Damaged braided hoses and poor crimps can lead to immediate leaking. This issue manifests immediately if present, so would drive replacement and therefore impact the end user in time to complete installation.

The customer communication requested return of unsold inventory to inspect for the spline size. If the spline size is incorrect it will not have a tight fit with the mating component, and would lead to detectable play and/or noise when steering.

ANALYSIS OF RETURNED POWER STEERING (PS) PUMPS THAT HAD BEEN REPLACED FOR NOISE, NO POWER ASSIST, NO OR LOW PRESSURE AND LEAKING CONDITIONS HAS INDICATED A HIGH NUMBER OF NO TROUBLE FOUND RESULTS. ALL 1997-2010 VEHICLES AND LIGHT TRUCKS; 2010 AND PRIOR HUMMERS H2/H3 AND SAAB 9-7X VEHICLES. *PE

noise from the metals making contact.

A CONDITION OF THE REAR ENTERTAINMENT SYSTEM NOT OPERATING AS INTENDED IN COLDER AMBIENT TEMPERATURE AREAS DUE TO CALIBRATION CONCERNS.