Chart A-2 Service Engine Soon Light ON Steady

Chart A-2:

Check Engine Light Circuit:

CIRCUIT DESCRIPTION:

The "CHECK ENGINE" indicator will flash diagnostic trouble codes when either the diagnostic request terminal in the duty check coupler or the diagnostic SW connector in the junction block is grounded.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. This will check for a grounded light circuit.

2. This will determine if it is an open diagnostic request terminal circuit or a faulty ECM.