Diagnostic Strategies

Fig. 2 ABS Scan Tool Information:

Most intermittent malfunctions are caused by loose or damaged electrical wiring and connectors. The scan tool can be used in several ways to aid in intermittent diagnosis. Connect scan tool to the ALDL connector with the engine not running, manipulate wiring harnesses or components under the hood, while observing the scan tool. Leaving scan tool connected to the ALDL connector, drive vehicle under the condition when the ABS fault first occurred. If the problem seems to be related to certain parameters that can be checked with the scan tool, they should be checked at this time. If there does not seem to be any correlation between the problem and any specific circuit, the scan tool can be checked on each position, watching for a period of time to see if there is any change in the readings that would indicate an intermittent malfunction.
The ABCM has the ability to take a snapshot of data with the last code stored. This can be done using the Malf History function of the scan tool and can be very useful when trying diagnose an intermittent code.