MMS 300 Engine Management System

All vehicles equipped with operational Malfunction Indicator Lamp (MIL) circuitry also have Diagnostic Trouble Code (DTC) permanent memory circuitry. The codes stored in memory must be manually erased following engine management system troubleshooting or repair procedures. Failure to clear trouble codes will limit many functions of the MPI ECM and reduce it's ability to deliver maximum operational performance. One method of clearing DTC memory is disconnect the vehicles battery for approx. 1 minute. While very simple and effective, also clears any other ECM memory that is normally maintained with the ignition turned OFF, such as the climate control ECM, radio station presets, drivers seat position presets, trip/mileage computer, etc.

To clear the MPI ECM Diagnostic Trouble Code Memory only;

1. Recall and display all ECM stored trouble codes. Reading Diagnostic Trouble Codes

2. Complete component functional checks. MMS 311 Engine Management System

Activating Data Link Connectors:

3. Once the codes have displayed and all components have been successfully checked, connect the jumper wire bridge connectors (A & B) together for at least 4 seconds then separate, code 0000 (end of output) will display on the MIL or LED tester.

^ Code 0000 display --- 2.5 second flash (zero) at 2.5 second intervals.

4. After display of code 0000 has been achieved, the DTC memory may be cleared by once again connecting the jumper wire bridge connectors (A & B) together for at least 4 seconds then separate. The DTC memory is now CLEAR.
5. After clearing the DTC memory, test drive vehicle for at least 5 minutes (minimum).
6. Activate DTC memory to ensure no new codes have been generated. If no new codes are present, code 4444 will display to confirm.