Chart A-1 No Service Engine Soon Light

Chart A-1 - No "Service Engine Soon" Light:

Wiring Diagram For Chart A-1 - No "Service Engine Soon" Light:

CHART A-1 - NO "SERVICE ENGINE SOON" LIGHT


CIRCUIT DESCRIPTION:

There should always be a steady "SERVICE ENGINE SOON" light when the ignition is "ON" and engine stopped. Battery ignition voltage is supplied to the light bulb. The PCM 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. If the fuse in holder is blown, refer to wiring diagram above for complete circuit of Code 54.

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 COMPUTER TERMINAL VOLTAGE VALUES under SPECIFICATIONS for PCM pin locations of ground circuits.


DIAGNOSTIC AIDS:

If the engine runs OK, check:

^ Faulty light bulb.
^ CKT 419 open.
^ Gage fuse blown. This will result in no brake warning light, oil or generator lights, seat belt reminder, etc.

If the engine cranks but will not run, check:

^ Continuous battery-fuse or fusible link open.
^ PCM ignition fuse open.
^ Battery CKT 440 to PCM open.
^ Ignition CKT 439 to PCM open.
^ Poor connection to PCM.