Diagnostic Aids
When attempting to diagnose an intermittent problem, use scan tester to review supplemental diagnostic information. Supplemental data (scan tester MALF HISTORY) can be used to help duplicate an intermittent problem. Using Diagnostic Service Probe (12092782) allows voltage to be read on wires without disconnecting connectors.
If using scan tester 42A, 42B or 42C will display at end of general information table. A 42A means by-pass is grounded, 42B means by-pass is open and a 42C means by-pass line is shorted to voltage.