Powertrain Controls - ECM/PCM

Diagnostic Chart:

Circuit Schematic:

IGNITION CONTROL (IC) CIRCUIT - OPEN OR SHORTED
The PCM provides the Ignition Control (IC) control circuit signal. The Electronic Ignition (EI) module uses this signal to fire the ignition coils, this is IC control circuit mode (bypass line high). In bypass mode, (bypass line low) the EI module will ground the IC control circuit line (EST) and generate an internal signal to fire the ignition coils. The EI module has the ability to force the bypass line low (Back-up Spark Control) in the event of missing IC control circuit pulses. The PCM monitors the state of the IC control circuit line while cranking and running.

DTC PARAMETERS

DTC 41 will set if:
^ The IC control circuit is open.
^ The IC control circuit is shorted to ground or voltage.

DIAGNOSTIC AIDS
When attempting to diagnose an intermittent problem use the Scan tool[1] to review supplemental diagnostic information. The supplemental data can be used to duplicate a problem.


Intermittents or opens suspected to be at the connector can be detected by using Diagnostic Service Probe. Voltage can be read on wires without disconnecting any connectors.

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

^ The PCM will hold IC control circuit low when there are no reference pulses.
^ PCM resistance with no IC control circuit output is approximately 14 milliohms.

If using the Saturn Portable Diagnostic (Scan) (PDT) Tool at the end of the General Information table will display a 41A or 41B.

^ 41A - IC control circuit open
^ 41B - IC control circuit shorted to ground or voltage.


[1] Select Malfunction History from Scan tool Engine Control (EC) menu.