Description of On-Board Diagnostics

Fig. 45 On-board self-test (Part 1 of 2).:

Fig. 45 On-board self-test (Part 2 of 2).:

The anti-lock brake electronic control module is capable of performing a self-test using Rotunda Star Tester model 007-00017 or SuperStar Tester 007-00019 or equivalents. The procedures for using the Star Tester are covered in the anti-lock self-test diagnosis chart, Fig. 45. If the star tester is not available the anti-lock Quick Check chart can be used as described further on.
The anti-lock control module monitors system operation and stores up to seven different service codes in its memory. However, it cannot store two service codes with the first (multiples of ten) digit. For example: The module cannot store a code 25 and a code 26 at the same time (it can however, store a code 25 and a code 35.) The code 25 is stored first. It must be serviced, then the memory cleared, and the vehicle driven before the code 26 can be stored.





A valve service code will override any stored service code during self-test. The condition must be serviced before any other codes can be displayed. After the valve has been serviced, the self-test can be run and any stored codes will be displayed. If no codes are displayed, the system has passed the self-test. If any codes are displayed during self-test, refer to the self-test code index, Fig. 46. The index will direct you to a specific pinpoint test. After the pinpoint tests have been completed, the components should be serviced. After servicing these codes the self-test should be repeated to see if any other codes have been stored in memory. These should then be serviced and the self-test repeated until no codes are displayed. After all codes have been displayed and serviced, the memory will be erased by driving the vehicle above 25 MPH. If the self-test has not been completed and all codes outputted, the memory cannot be erased.