Diagnostic Notes

As previously mentioned, intermittent concerns are the most difficult to diagnose.

An understanding of code storage and automatic code erasure is important.

First, codes can only be stored if the antilock electronic control module has power. The antilock electronic control module gets primary power from the ignition feed into Pins 1 and 9. If this voltage is missing or less than 11V, the antilock electronic control module will not initialize and therefore, a code cannot be stored. However, any code already in memory will be retained as long as the Keep Alive Memory power is available. Code 16 (system OK) is present whenever the antilock electronic control module sees the required voltage (assuming no other diagnostic trouble codes are present).

Therefore, some codes read out in the System Pre-Check may not result in any trouble found in the pinpoint test performed. More likely, this is an indication of an intermittent electrical concern.

At times, running completely through a pinpoint test will not lead to a concern resolution. Often, the concern is due to an intermittent connection, termination, or a damaged circuit. An attempt has been made to point out obvious sources for potential intermittents within the pinpoint tests. However, it should be noted that several circuits pass through one or more connections between components. These are also areas of potential concern and should be considered.