- Hewlett-Packard Printer User Manual

Pressing the Test Print button will initiate a 15 ENGINE TEST.
This is an engine test only. The Format PCA is bypassed while
printing this test, although a formatter problem can interfere
with this test. A page of vertical lines is printed if the print
engine is operating correctly (see Figure 3-6).
Figure 3-6 Test Print Pattern
3-30 Configuration