Chart A-2 Engine Control System Lamp ON No Codes Present

Chart A-2:

DESCRIPTION:

The Engine Control System (ECS) lamp is powered through the 10 AMP "Ign-1" fuse number 18 in the fuse block, and grounded by the ECM Pin "C1" to illuminate. The ECS telltale will bulb check at key on, is illuminated steadily during cranking and is illuminated whenever a trouble code with a service message is set. If a service trouble code is set, the ECM will send a service status to the BCM over the Universal Asynchronus Receiver Transmitter (UART) data link. At the same time, the ECM grounds Pin "C1" to turn "ON" the ECS telltale.

NOTES ON CHART A-2:

1. A flickering "Engine Control System" lamp may be caused by an incorrect "Set Timing Request".


2. Checking for bulb grounded by ECM through Pin "C1" or through a circuit fault.

3. Remove and reconnect both ECM connectors and ensure that they are latched. Check the Mem-Cal for proper orientation and make sure the Mem-Cal socket is fully seated. 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 ECM. Be sure to perform "ECM Replacement Check", CHART C-1.