Frame Reference Point Description
Reference points are locations on a vehicle which correspond to specific measuring points. Use the reference points when checking the vehicle structure.
Dimension charts may use the center of a hole, bolt head, or nut, etc. as a reference point. A description and location chart will tell you how and where the measurements should be taken. The most accurate reference point is a gauge hole or a control hole used by the assembly plant in order to control tolerances when the vehicle was built. Refer to Frame Control Hole Description for more information about control holes.
Scheme 9
Control holes are round or oval holes located in the underbody structure sections, the upper body, and the body sides. Some control holes can be identified from other holes by a turned up lip on the inside of the hole. This reinforced lip reduces the possibility of hole distortion and increases accuracy during assembly. Utilize control points whenever possible when measuring underbody dimensions, in order to obtain the most accurate readings.
Scheme 10
Symmetrical reference points are 2 corresponding points on opposite sides of the centerline that have equal specifications in length, width, and height. Use symmetrical reference points in order to make quick inspections for underbody structural damage.
Frame Reference Point Description - Asymmetrical
When 2 corresponding reference points have different measurements, they are called asymmetrical. If you perform a quick cross check and the measurements are unequal, you should check the dimension charts in order to find out if the measuring points are symmetrical or asymmetrical.
Running Board Description
The running boards are a dealer installed option that are mounted on factory installed brackets. The brackets are located under the vehicle.