GM Full-Size Trucks 1970-1979 Repair Guide

Ignition Lock Cylinder

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REMOVAL & INSTALLATION



1973-78 Vehicles

See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: Ignition lock cylinder removal - 1973-78 vehicles

  1. Remove steering wheel and turn signal switch.
  2.  

It is not necessary to completely remove the turn signal switch. Pull the switch over the end of the shaft; no further.

  1. Place lock cylinder in RUN position.
  2.  

Do not remove the ignition key buzzer.

  1. Insert a small drift pin into the turn signal housing slot. Keeping the drift pin to the right side of the slot, break the housing flash loose and depress the spring latch at the lower end of the lock cylinder. Remove the lock cylinder.
  2.  


WARNING
Considerable force may be necessary to break this casting flash, but be careful not to damage any other parts. When ordering a new lock cylinder, specify a cylinder assembly. This will save assembling the cylinder, washer, sleeve and adapter.

To install:
  1. Hold the lock cylinder sleeve and rotate the knob clockwise against the stop.
  2.  
  3. Insert the cylinder into the housing, aligning the key and keyway.
  4.  
  5. Hold a 0.070 in. drill between the lock bezel and housing. Rotate the cylinder counterclockwise, maintaining a light pressure until the drive section of the cylinder mates with the sector.
  6.  
  7. Push in until the snapring pops into the grooves. Remove drill. Check cylinder operation.
  8.  

The drill prevents forcing the lock cylinder inward beyond its normal position. The buzzer switch and spring latch can hold the lock cylinder in too far. Complete disassembly of the upper bearing housing is necessary to release an improperly installed lock cylinder.

1979 Vehicles

See Figure 2



Click image to see an enlarged view

Fig. Fig. 2: Ignition lock cylinder removal and installation - 1979 vehicles

  1. Remove the steering wheel, as outlined earlier in this section.
  2.  
  3. Remove the turn signal switch. It is not necessary to completely remove the switch from the column. Pull the switch rearward far enough to slip it over the end of the shaft, but do not pull the harness out of the column.
  4.  
  5. Turn the lock to RUN .
  6.  
  7. Remove the lock retaining screw and remove the lock cylinder.
  8.  


WARNING
If the retaining screw is dropped on removal, it may fall into the column, requiring complete disassembly of the column to retrieve the screw.

  1. To install, rotate the key to the stop while holding onto the cylinder.
  2.  
  3. Push the lock all the way in.
  4.  
  5. Install the screw. Tighten the screw to 3 ft. lbs. (4.1 Nm) for regular columns, or to 2 ft. lbs. (2.7 Nm) for tilt columns.
  6.  
  7. Install the turn signal switch and the steering wheel.
  8.  

 
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