Powertrain Controls - ECM/PCM

Diagnostic Chart.:

Ignition System Wiring.:

DESCRIPTION


The PCM/EC enables the EST mode by switching the bypass line high. When the bypass line is low the DIS module controls secondary coil firing. To enable EST the PCM/EC applies 5 volts on the bypass line (at approximately 400 RPM) indicating EST Mode to the DIS module. In EST mode the DIS module uses the EST signal from the PCM/EC to fire the secondary coils. The PCM/EC has internal feedback to monitor the state of the bypass line.

CODE PARAMETERS

Code 42 will set if:


^ The bypass line is open.


^ The bypass line is grounded.


^ The bypass line is shorted to voltage.

DIAGNOSTIC AIDS

^ When attempting to diagnose an intermittent problem use the Scan Tool to review supplemental diagnostic information. The supplemental data can be used to duplicate a problem. Select MALF History from Scan Tool TC menu.


^ Check the tightness of the female terminal grip with a spare male terminal.


^ Refer to DIS in the Ignition section.


If using the SATURN PDT, at the end of the General Information table it will display a 42A, 42B, or 42C. Scan Tool Testing and Procedures


^ 42A - Bypass line grounded.


^ 42B - Bypass line open.


^ 42C - Bypass line shorted to voltage.