Suspension Vibration Or Frame Beaming At 40-60 MPH (64-80 KM/H) - keywords front rear shake shock spring tire

This PI was superseded to update models and buyback info. Please discard PIT3009F.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Beam shake vibration is usually felt in the seat and occurring at speeds between 40-50 mph (64 - 80 km/h). Hertz readings using an EVA tool are normally between 8-24 Hz. This condition is most common on extended cab and crew cab models but has also been noted in other models.

The severity of beam shake may vary from vehicle to vehicle. To determine if the concern is beam shake, please perform the following:

1. Test drive vehicle to confirm the condition. A beam shake condition will usually respond to concrete type pavements more than asphalt, so the vehicle should be driven over both surfaces if possible.
2. Place 200-500 pounds in the pickup bed between the closed tailgate and the wheel wells. A beaming condition should dissipate.

Note: Tires with excessive Radial Force Variation (RFV) or out-of-roundness can intensify the frame beaming concern. The following radial force variation numbers should be used as a guide:

P-Metric tires (2wd 1500) 12 lbs or less

P-Metric tires (all others) 24 lbs or less

LT-tires 30 lbs or less

If the concern is determined to be beam shake, this is a characteristic of the vehicle and currently no repair attempts should be made. GM Engineering is currently working on reducing this concern for the light duty 1500 Crew and Extended Cab Models. There will be no changes made to the 1500 regular cab, 1500HD, 2500 or 3500 models.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.