Operation CHARM: Car repair manuals for everyone.

With Generic Scan Tool

SETTING CODES
The PCM has been programmed to verify that circuit parameters remain within the acceptable range established for each monitored circuit.

If a circuit parameter is detected outside of limits and ALL other Arming Conditions are met, a corresponding DIAGNOSTIC TROUBLE CODE (DTC) will be stored in PCM memory.

A DTC for will not be set unless ALL of the arming criteria needed to set the code have been met.

Example;

Assume the arming criteria for a sensor circuit DTC include requiring the engine to operate between 750 and 2000 RPM.

- If the sensor output circuit shorts to ground when engine RPM is ABOVE 2400 RPM,

- Then a diagnostic trouble code will not be entered into memory, (because the condition does not occur within the specified RPM range).

Arming Criteria
- Engine RPM

- Engine Temperature

- Input Voltage To The PCM

DISPLAYING CODES
Trouble codes stored in PCM memory can be displayed in two ways;

1. Cycling the ignition key On - Off - On - Off - On, and observing the Check Engine light.

2. Through a scan tool connected to the vehicle data link connector.

CLEARING CODES
The PCM will cancel DTC's after 51 vehicle key ON/OFF cycles, if the problem is repaired or ceases to exist.