Frame & Underbody: Removal & Installation GMC Yukon II

Removal Procedure

1. Raise the vehicle. Refer to «LIFTING & JACKING THE VEHICLE»(ref-178095) .
2. Support the transmission with a transmission jack.
3. Remove the nut retaining the transmission mount to the transmission support.
4. Raise the rear of the transmission.
5. Remove the bolts and the nuts retaining the transmission support to the frame. (15 series)
6. Remove the bolts and the nuts retaining the transmission support to the frame. (25/35 series)
7. Remove the transmission support from the frame.

Installation Procedure

1. Install the transmission support to the frame. (15 series)
2. Install the transmission support to the frame. (25/35 series)
3. Install the bolts and the nuts in order to retain the transmission support to the frame. Tighten: Tighten the nuts to 95 N.m (70 lb ft).
4. Lower the rear of the transmission.
5. Install the transmission mount to the transmission support.
6. Install the nuts in order to retain the transmission mount to the transmission support. Tighten: Tighten the nuts to 40 N.m (30 lb ft).
7. Remove the transmission jack.
8. Lower the vehicle.

Frame Cushion or Insulator Replacement (Tahoe/Yukon)

1. Remove the master cylinder. Perform the following steps: Remove the nuts retaining the master cylinder to the brake booster. Remove the master cylinder from the brake booster. Secure the cylinder away from the booster.
2. Raise the vehicle on the hoist. Refer to «LIFTING & JACKING THE VEHICLE»(ref-178095) .
3. Remove the park brake equalizer intermediate cable. Perform the following steps: Remove the nut from the park brake equalizer intermediate cable. Remove the intermediate cable from the equalizer. Depress the retaining tabs that secure the park brake cable to the frame. Pull slightly on the cable from the mounting area in order to provide slack for body movement without binding the cable.
4. Remove the body mount bolts.
5. Properly support the body in the area that the mounts will be replaced.
6. Lower the chassis accordingly in order to remove the cushions (1) as necessary.

1. Install the cushions (1) as necessary and raise the chassis accordingly.
2. Install the body mount bolts. Tighten: Tighten the bolts to 85 N.m (63 lb ft).
3. Install the park brake equalizer intermediate cable. Perform the following steps: Pull rearward on the park brake cable to the original position. Secure the cable retaining tabs to the frame. Install the intermediate cable end to the equalizer. Install the nut to the threaded end of the intermediate cable. Tighten: Tighten the nut to 3.5 N.m (31 lb in).
4. Lower the vehicle.
5. Install the master cylinder. Perform the following steps: Mount the master cylinder to the brake booster. Install the master cylinder mounting nuts. Tighten: Tighten the nuts to 36 N.m (27 lb ft).

Frame Cushion or Insulator Replacement (Suburban/Yukon XL)

1. Remove the master cylinder. Perform the following steps: Remove the nuts retaining the master cylinder to the brake booster. Remove the master cylinder from the brake booster. Secure the cylinder away from the booster.
2. Raise the vehicle on the hoist. Refer to «LIFTING & JACKING THE VEHICLE»(ref-178095) .
3. Remove the park brake equalizer intermediate cable. Perform the following steps: Remove the nut from the park brake equalizer intermediate cable. Remove the intermediate cable from the equalizer. Depress the retaining tabs that secure the park brake cable to the frame. Pull slightly on the cable from the mounting area in order to provide slack for body movement without binding the cable.
4. Remove the body mount bolts.
5. Properly support the body in the area that the mounts will be replaced.
6. Lower the chassis accordingly in order to remove the cushions (1) as necessary.

1. Install the cushions (1) as necessary and raise the chassis accordingly.
2. Install the body mount bolts. Tighten: Tighten the bolts to 85 N.m (63 lb ft).
3. Install the park brake equalizer intermediate cable. Perform the following steps: Pull rearward on the park brake cable to the original position. Secure the cable retaining tabs to the frame. Install the intermediate cable end to the equalizer. Install the nut to the threaded end of the intermediate cable. Tighten: Tighten the nut to 3.5 N.m (31 lb in).
4. Lower the vehicle.
5. Install the master cylinder. Perform the following steps: Mount the master cylinder to the brake booster. Install the master cylinder mounting nuts. Tighten: Tighten the nuts to 36 N.m (27 lb ft).

1. Disconnect the trailer wiring harness.
2. Remove the hitch platform bolts from the frame rails and the rear bumper.
3. Remove the hitch platform from the vehicle.

1. Position the hitch platform to the vehicle.
2. Install the platform hitch bolts to the frame rails and the rear bumper. Tighten: Tighten the bolts to 125 N.m (92 lb ft).
3. Connect the trailer wiring harness.

1. Remove the front bumper. Refer to «BUMPER REPLACEMENT - FRONT (OLD STYLE)»(ref-189507-S22660480552005090800000) .
2. Remove the tow hook bolts from the frame rail.
3. Remove the tow hook from the vehicle.

1. Install the tow hook to the frame rail.
2. Install the bolts to the tow hook through the frame rail. Tighten: Tighten the bolts to 85 N.m (63 lb ft).
3. Install the front bumper. Refer to «BUMPER REPLACEMENT - FRONT (OLD STYLE)»(ref-189507-S22660480552005090800000) .

1. Remove the tow hook bolts from the frame rail.
2. Remove the tow hook from the vehicle.

1. Install the tow hook to the frame rail.
2. Install the bolts to the tow hook through the frame rail. Tighten: Tighten the bolts to 85 N.m (63 lb ft).

1. Remove the push-in retainer from the assist step front cover.
2. Remove the cover from the vehicle.
3. Remove the retainer clip from the assist step rear cover.
4. Remover the cover from the vehicle.
5. Remove the bottom fender bolt (2) and the washer (1) from the vehicle.
6. With the aid of an assistant, remove the bolts (1, 5) and the nuts (2, 3) from the assist step brackets.
7. Remove the assist step from the vehicle.
8. Remove the heater and A/C tubes retaining nuts from the studs, if equipped. Refer to «HEATER PIPE»(ref-131951-S38279423752003071400000) .
9. Remove the assist step bolts (6) from the brackets.
10. Remove the brackets (4) from the vehicle.

1. Install the assist step brackets to the vehicle (4).
2. Install the bolts (6) to the brackets and ensure that the brackets are seated securely to the inner rocker panel.
3. Install the heater and A/C tubes retaining nuts to the studs, if equipped. Refer to «HEATER PIPE»(ref-131951-S38279423752003071400000) .
4. With the aid of an assistant, install the assist step to the vehicle.
5. Install the bolts (1, 5) and the nuts (2, 3) to the assist step bracket, and leave the nuts loose.
6. Install the bottom fender bolt (2) and the washer (1) to the vehicle. Tighten: Tighten the bottom fender bolt (2) to 25 N.m (18 lb ft).
7. Tighten the assist step fasteners in the following sequence: Tighten: Tighten the bracket bolt (6) to 25 N.m (18 lb ft). Tighten the assist step bracket nut (2) to 9 N.m (80 lb in). Tighten the assist step to the bracket nut (3) to 9 N.m (80 lb in).
8. Install the assist step rear cover to the vehicle.
9. Install the clip retainer.
10. Install the assist step front cover to the vehicle.
11. Install the push-in retainer.

1. Remove the push-in retainer from the assist step front cover.
2. Remove the cover from the vehicle.
3. Remove the push-in retainer from the assist step rear cover.
4. Remover the cover from the vehicle.
5. Remove the bottom fender bolt (2) from the vehicle.
6. With an assistant, remover the bolts (3,1) from the assist step brackets.
7. Remove the assist step from the vehicle.
8. Remove the heater and A/C tubes retaining nuts from the studs, if equipped. Refer to «HEATER PIPE»(ref-131951-S38279423752003071400000) .
9. Remove the assist step bolts (6) from the brackets.
10. Remove the brackets from the vehicle.

1. Install the assist step brackets to the vehicle.
2. Install the bolts (6) to the brackets and ensure that the brackets are seated securely to the inner rocker panel.
3. Install the heater and A/C tubes retaining nuts to the studs, if equipped. Refer to «HEATER PIPE»(ref-131951-S38279423752003071400000) .
4. With an assistant, install the assist step to the vehicle.
5. Install the bolts (3,1) to the assist step bracket, and leave the bolts loose.
6. Install the bottom fender bolt (2) and the washer to the vehicle.
7. Tighten the assist step fasteners in the following sequence: Tighten: Tighten the front fender bolt to 25 N.m (18 lb ft). Tighten the bracket bolt to 25 N.m (18 lb ft). Tighten the assist step bracket bolt (2) to 9 N.m (80 lb in). Tighten the assist step to the bracket bolt to 9 N.m (80 lb in).
8. Install the assist step rear cover to the vehicle.
9. Install the push-in retainer.
10. Install the assist step front cover to the vehicle.
11. Install the push-in retainer.

1. With the aid of a helper, remove the retaining nuts and the spacers (1) from the bottom side of the assist step, and remove the assist step from the vehicle.
2. Remove the rocker panel molding. Refer to «MOLDING REPLACEMENT - ROCKER PANEL (Z-71)»(ref-178461-S14433670172005091400000) or «MOLDING REPLACEMENT - ROCKER PANEL (UTILITY)»(ref-178461-S19168170032005091400000) .
3. Drill out the rivets (1) from the assist step brackets.
4. Remove the 5 stud plates (1) from the 5 assist step brackets (2).
5. Remove the 5 retaining bolts (1) from the inner side of the rocker panel.
6. Remove the 5 retaining bolts (2) from the inner side of the rocker panel.
7. Remove the assist step brackets (5) from the vehicle.
8. Drill out the rivets (3) for the rocker panel molding bracket (4).
9. Remove the bracket (4) from the vehicle.

1. Install the rocker panel molding bracket (4) to the vehicle.
2. Install the rivets (3) that secure the rocker panel molding bracket (4) to the vehicle.
3. Install the assist step brackets (5) to the vehicle.
4. Install the 5 retaining bolts (1) to the inner side of the rocker panel. Tighten: Tighten the bolts (1) to 29 N.m (21 lb ft).
5. Install the 5 retaining bolts (2) to the inner side of the rocker panel. Tighten: Tighten the bolts (1) to 10 N.m (89 lb in).
6. Install the 5 stud plates (1) to the 5 assist step brackets (2).
7. Install the rivets (1) that secure the assist step brackets to the rocker panel.
8. Install the rocker panel molding. Refer to «MOLDING REPLACEMENT - ROCKER PANEL (Z-71)»(ref-178461-S14433670172005091400000) or «MOLDING REPLACEMENT - ROCKER PANEL (UTILITY)»(ref-178461-S19168170032005091400000)
9. With the aid of an assistant, install the assist step to the vehicle.
10. Install the spacers and the nuts (1). Tighten: Tighten the bolts (1) to 29 N.m (21 lb ft).

1. Remove the frame to the shield bolts.
2. Remove the shield from the vehicle. 15 Series is shown, 25 Series is similar.

1. Install the shield to the vehicle. 15 Series is shown, 25 Series is similar.
2. Install the shield to frame bolts. Tighten: Tighten the bolts to 20 N.m (15 lb ft).

1. Remove the bolts that attach the running board end caps to the body.
2. Remove the bolts that secure the running board to the brackets.
3. Remove the running boards from the vehicle.
4. Loosen the bolts retaining the HVAC pipes in order to facilitate the removal the assist step brackets. Refer to «HEATER PIPE»(ref-131951-S38279423752003071400000) .
5. Remove the bolts attaching the brackets to the vehicle.
6. Remove the brackets.

1. Install the brackets to the vehicle.
2. Install the bolts that secure the brackets to the vehicle. Tighten: Tighten the bolts to 25 N.m (18 lb ft).
3. Install the running board assembly to the vehicle.
4. Install the bolts that secure the running boards to the brackets. Tighten: Tighten the bolts to 25 N.m (18 lb ft).
5. Install the bolts retaining the HVAC pipes in order to facilitate the installation of the assist step brackets. Refer to «HEATER PIPE»(ref-131951-S38279423752003071400000) . Tighten: Tighten the bracket bolts to 25 N.m (18 lb ft).
6. Install the bolts that secure the end caps to the vehicle. Tighten: Tighten the bolts to 25 N.m (18 lb ft).

1. Remove the battery ground (negative) cable. CAUTION: Refer to «BATTERY DISCONNECT CAUTION»(ref-175132-S30614301632005041500000) .
2. Remove the frame bolt (2) from the frame crossmember nut.
3. Break away the spot welds (1) on one side of the frame crossmember nut retainer with an air chisel.
4. Lift one side of the frame crossmember nut retainer (enough to remove the frame crossmember nut).
5. Remove the frame crossmember nut.

1. Install the frame crossmember nut (2).
2. Install the lower frame crossmember nut retainer into place to insure proper placement and working condition of the frame crossmember nut.
3. Install the spot weld (3) frame crossmember nut retainer in the original location.
4. Clean and prepare the welded surfaces.
5. Install the new frame bolt to the frame crossmember nut. Tighten: Tighten the bolt to 180 N.m (133 lb ft).
6. With a pressure pot apply the anticorrosion compound GM P/N 12346225 or equivalent and coat the inside of the repair area through any access hole thoroughly.
7. Connect the battery ground (negative) cable.

Scheme 11

1. A datum is an imaginary horizontal plane that runs 2 ways to the vehicle: Below
2. Parallel Calculate the height dimensions at right angles from the datum to a given control reference point on the underbody.

The company that develops height dimensions determines the location of the datum based on the equipment used. Different datum lines are established for the same vehicle. Add or subtract an equal amount from all height dimensions. Create a new datum line for your usage.

Scheme 12

A centerline is an imaginary vertical plane that is perpendicular to the length of the datum plane through the center of the vehicle. The centerline is any line drawn through the center of the vehicle's datum. The symbol for centerline is CL.