Chart A-2 No Codes Service Engine Soon Light ON Steady

PFI Chart A-2:

PFI Service Engine Soon Lamp Circuit:

DESCRIPTION:

The "Service Engine Soon" (SES) lamp is powered through the IPC and grounded by the ECM pin A10 to illuminate. The SES telltale will bulb check at key "ON", is illuminated steadily during cranking, and is illuminated whenever a trouble code with service message is set. The SES telltale will flicker when pin A and pin B of the ALDL connector are jumpered together to enter set timing mode.

NOTES ON CHART A-2:

1. Loose grounds or intermittent power connections can cause the PCM/ECM to repeatedly power up then power down or to reset.

2. Checking for bulb grounded by PCM/ECM through pin A10, or through a circuit fault.

3. Remove and replace both PCM/ECM connectors and ensure that they are latched. Check the MEM-CAL for proper orientation, pins bent, fully seated in the socket. Substitute a test MEM-CAL to see if the MEM-CAL is causing the light to flicker. If the test MEM-CAL does not correct the condition, replace the PCM/ECM. Be sure to perform the PCM/ECM Replacement Check, Chart C-1. The PCM/ECM may be damaged due to electrical overload from a low resistance component.