Regal V6-231 3.8L VIN L SFI (1990)
Chart A-1 Wiring Diagram
CIRCUIT DESCRIPTION:
There should always be a steady "SERVICE ENGINE SOON" light when the ignition is "ON" and engine stopped. Ignition voltage is supplied to the
light bulb. The ECM will control the light and turn it "ON" by providing a ground path through CKT 419.
TEST DESCRIPTION:Numbers below refer to circled numbers on the diagnostic chart.
1.
"SERVICE ENGINE SOON" light should be "ON."
2.
Using a test light connected to 12 volts, probe each of the system ground circuits to be sure a good ground is present. See ECM CONNECTOR
IDENTIFICATION in ELECTRICAL AND ELECTRONIC DIAGRAMS for ECM pin locations of ground circuits.
DIAGNOSTIC AIDS:
If the engine runs OK, check:
^
Faulty light bulb.
^
CKT 419 or 39 open.
^
10 Amp indicator fuse is bad.
If the engine cranks but will not run, check:
^
Continuous battery-fusible link open.
^
15 Amp ECM ignition fuse is bad.
^
Ignition CKT 439 to ECM open.
^
Circuit 440 to ECM open.
^
10 Amp ECM battery fuse is bad.
^
Ignition circuit to 439 to ECM is open.
^
Poor connection to ECM.
